CN116156166A - Image encoding method, image decoding method and device thereof - Google Patents

Abstract

The invention provides an image encoding method, an image decoding method and a device thereof. An image decoding method, comprising: obtaining information on transform coefficients of a current block from a bitstream; determining a filter for the current sample point based on at least one of a distance between the current sample point and a reference sample point in the current block and a size of the current block; obtaining a prediction block of the current block including prediction samples of the current samples generated using the determined filter; obtaining a residual block of the current block based on the obtained information on the transform coefficients of the current block; and restoring the current block based on the prediction block of the current block and the residual block of the current block.

Description

Image encoding method, image decoding method and device thereof

This application is a divisional application of the application submitted to the State Intellectual Property Office with the filing date of October 31, 2018, titled "Image Coding Method, Image Decoding Method and Device", and application number 201880084999.9.

technical field

The method and apparatus thereof according to embodiments may encode or decode an image by using various shapes of coding units included in the image. The method and device thereof according to the embodiments include an intra prediction method and device thereof.

Background technique

As hardware capable of reproducing and storing high-resolution or high-quality image content is being developed and provided, demands for codecs that efficiently encode or decode high-resolution or high-quality image content are increasing. Encoded image content can be reproduced by decoding. Recently, methods for efficiently compressing content such as high-resolution or high-quality images have been implemented. For example, a method of efficiently compressing an image is performed by processing an image to be encoded via an arbitrary method.

Various data units can be used to compress the image, and a containment relationship can exist between these data units. The data unit may be divided by various methods to determine the size of the data unit used for compression of these images, and as the data unit optimized according to the characteristics of the image is determined, encoding or decoding may be performed on the image.

Contents of the invention

Technical solutions

An image decoding method according to an embodiment, which includes: obtaining information about a transform coefficient of a current block from a bitstream; a filter for the current sample; obtaining a prediction block of the current block including a prediction sample of the current sample generated using the determined filter; obtaining the current block based on the obtained information about the transform coefficient of the current block and restoring the current block based on the prediction block of the current block and the residual block of the current block.

The step of determining the filter for the current sample based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block may include: At least one of the distance between samples and the size of the current block is used to determine the type of filter used for the current sample and the coefficients of the filter.

The type of filter can be low pass filter (low pass filter), Gaussian filter (Gaussian filter), bilateral filter (bilateral filter), uniform filter (uniform filter), bilinear interpolation filter (bilinear interpolation filter), cubic filter (cubic filter) and discrete cosine transform (Discrete Cosine Transform; DCT) filter (DCT filter).

The number of taps of the filter for the current sample is a predetermined value, or is determined based on at least one of the distance between the current sample and the reference sample and the size of the current block. The predetermined value may be an integer equal to or greater than 4.

The step of determining the filter for the current sample based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block may include: based on the size of the current block and the size of the current block determining a plurality of filters for the current block by at least one of the distances between the sample point and the reference sample point; and determining a filter corresponding to the current sample point among the plurality of filters for the current block.

The step of determining a plurality of filters for the current block based on at least one of the size of the current block and the distance between the current sample in the current block and the reference sample may include: based on the height or width of the current block and the current The ratio of the distance between the samples in the block and the reference samples is used to determine the number of filters for the current block.

The step of determining the filter for the current sample based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block may include: determining based on the intra prediction mode of the current block a first reference sample corresponding to a sample in the current block; determining a plurality of filters for the current block based on a distance between the sample and the first reference sample; and A filter corresponding to the current sample point is determined among the plurality of filters.

The step of determining the filter for the current sample based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block may include: determining the filter for the current sample based on the size of the current block the number of filters for the block, and determine the filter for the current block corresponding to the number of filters; and based on the distance between the current sample point and the reference sample point and the size of the current block The filter for the current sample is determined in the filters for the block.

The step of determining the filter for the current sample based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block may include: further based on the intra prediction mode and At least one of the shapes of the current block to determine the filter for the current sample.

The step of determining the filter for the current sample further based on at least one of the intra prediction mode of the current block and the shape of the current block may include:

When the intra prediction mode of the current block is a predetermined intra prediction mode, the current sample is determined based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block. filter.

The step of determining the filter for the current sample further based on at least one of the intra prediction mode of the current block and the shape of the current block may include:

When the width of the current block is less than or equal to a predetermined first value, and the height of the current block is less than or equal to a predetermined second value, based on the distance between the current sample point and the reference sample point in the current block and the size of the current block at least one of them to determine the filter to use for the current sample.

The step of determining the filter for the current sample based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block may include: when the distance between the current sample and the reference sample When the distance is less than a predetermined value, determine the first filter for the current sample point, and when the distance between the current sample point and the reference sample point is greater than a predetermined value, determine the second filter for the current sample point, The smoothing strength of the first filter may be less than the smoothing strength of the second filter.

An image encoding method according to an embodiment includes: determining a filter for a current sample based on at least one of a distance between a current sample in a current block and a reference previous sample and a size of the current block; generating includes using the A prediction block of a current block of a prediction sample of the current sample generated by the determined filter; and encoding information about a transform coefficient of the current block based on the prediction block of the current block.

An image decoding device according to an embodiment includes: a processor that obtains information about transform coefficients of a current block from a bitstream; one to determine a filter for the current sample point; obtain a prediction block of the current block including a prediction sample point of the current sample point generated using the determined filter; based on the obtained information about the transform coefficient of the current block obtaining a residual block of the current block; and restoring the current block based on the predicted block of the current block and the residual block of the current block.

According to an embodiment of the present disclosure, a computer program related to an image decoding method may be recorded on a computer-readable recording medium.

Description of drawings

Fig. 1a illustrates a block diagram of an image decoding device according to various embodiments.

Fig. 1b illustrates a flowchart of an image decoding method according to various embodiments.

Fig. 1c illustrates a block diagram of an image decoder according to various embodiments.

Fig. 1d illustrates a block diagram of an image decoding device according to various embodiments.

Fig. 2a illustrates a block diagram of an image encoding device according to various embodiments.

Fig. 2b illustrates a flowchart of an image encoding method according to various embodiments.

Fig. 2c illustrates a block diagram of an image decoder according to various embodiments.

Fig. 2d illustrates a block diagram of an image encoding device according to various embodiments.

FIG. 3 illustrates a process of determining at least one coding unit as an image decoding device splits a current coding unit, according to an embodiment.

FIG. 4 illustrates a process in which an image decoding device divides coding units having a non-square shape to determine at least one coding unit, according to an embodiment.

FIG. 5 illustrates a process in which an image decoding device splits a coding unit based on at least one of block shape information and split shape pattern information according to an embodiment.

FIG. 6 illustrates a method of determining a predetermined coding unit from among odd coding units by an image decoding device, according to an embodiment.

FIG. 7 illustrates an order of processing a plurality of coding units when an image decoding device divides a current coding unit to determine a plurality of coding units, according to an embodiment.

FIG. 8 illustrates a process of determining that a current coding unit is split into an odd number of coding units when the coding units cannot be processed by an image decoding device in a predetermined order, according to an embodiment.

FIG. 9 illustrates a process of determining at least one coding unit as an image decoding device splits a first coding unit, according to an embodiment.

FIG. 10 illustrates that a shape in which a second coding unit may be divided is limited when a second coding unit determined to have a non-square shape by which a first coding unit is divided satisfies a predetermined condition, according to an embodiment of an image encoding device.

11 illustrates a process in which an image decoding device divides a coding unit having a square shape when the division shape pattern information cannot indicate that the coding unit is divided into four square shapes, according to an embodiment.

FIG. 12 illustrates that a processing order of a plurality of coding units may vary according to a process of dividing a coding unit according to an embodiment.

13 illustrates a process in which a depth of a coding unit is determined as the shape and size of the coding unit vary when the coding unit is recursively split to determine a plurality of coding units, according to an embodiment.

FIG. 14 illustrates a depth and an index (part index, hereinafter PID) for distinguishing a coding unit, which may be determined according to a shape and size of a coding unit, according to an embodiment.

FIG. 15 illustrates determining a plurality of coding units according to a plurality of predetermined data units included in a picture, according to an embodiment.

16 illustrates processing blocks used as a criterion for determining a determination order of reference coding units included in a picture according to an embodiment.

FIG. 17 is a diagram for explaining an intra prediction mode according to an embodiment.

18 is a diagram for explaining that according to an embodiment of the present disclosure, an image decoding device generates a current sample by using different filters based on at least one of the distance between the current sample and the reference sample and the size of the current block. Method for predicting sample points.

FIG. 19 is used to illustrate that according to an embodiment of the present disclosure, the encoding (decoding) order between coding units is determined as forward or reverse based on the encoding order flag, and the right reference line or the upper part is determined according to the encoding (decoding) order. Reference lines can be used for intra-predicted images.

best mode

A video decoding method according to various embodiments includes: obtaining information about transform coefficients of a current block from a bitstream; determining a filter for the current sample; obtaining a prediction block of the current block including a prediction sample of the current sample generated using the determined filter; obtaining the current a residual block of the block; and restoring the current block based on the predicted block of the current block and the residual block of the current block.

A video encoding method according to various embodiments includes: determining a filter for a current sample based on at least one of a distance between a current sample in a current block and a reference previous sample and a size of the current block; generating a filter comprising: a prediction block of the current block of a prediction sample of the current sample generated using the determined filter; and encoding information on transform coefficients of the current block based on the prediction block of the current block.

A video decoding apparatus according to various embodiments includes: a processor that obtains information about transform coefficients of a current block from a bitstream; to determine a filter for the current sample; obtain a prediction block of the current block including a prediction sample of the current sample generated using the determined filter; information to obtain a residual block of the current block; and restore the current block based on the prediction block of the current block and the residual block of the current block.

According to another aspect of the present disclosure, a computer readable recording medium has recorded thereon a program for executing methods according to various embodiments.

Detailed ways

The advantages and features of the disclosed embodiments, and methods for achieving the advantages and features will become more apparent with reference to the embodiments described below and the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, and can be implemented in various forms, and the present embodiments are provided only to make the present disclosure more complete and to fully inform those skilled in the art to which the present disclosure belongs the scope of the invention. .

Terms used in the specification will be briefly described, and the disclosed embodiments will be described in detail.

The terms used in this specification have selected general terms that may be widely used currently when functions in the present disclosure are considered, but may be changed according to intentions of those skilled in the art or precedents, appearance of new technologies, and the like. Also, some terms may be arbitrarily selected by the applicant, and in this case, the meanings of the selected terms will be described in detail in the attached Summary of the Invention. Therefore, the terms used in the present disclosure should be defined based on the meanings of the terms and the descriptions throughout the specification, not just the names of the terms.

Expressions used in the singular include plural expressions unless the expressions used in the singular have clearly different meanings in the context.

In the specification, when a certain component includes "a certain constituent element, unless there is an explicit description to the contrary, the component may further include other constituent elements without excluding other constituent elements.

In addition, the term "device" used in the specification refers to a software or hardware constituent element, and the "device" performs a predetermined function. However, the term "device" is not limited to software or hardware. A "device" may be formed to reside in an addressable storage medium, or may be formed to reproduce one or more processors. Thus, as an example, a "device" includes components such as software components, object-oriented software components, class components, and task components, and may include processes, functions, functions, attributes, steps, subcases program, program code segment, driver, firmware, microcode, circuit, data, database, data structure, table, array, or variable. Functions provided within the constituent elements and "device" may be combined by a smaller number of constituent elements and "device", or may be divided by additional constituent elements and "device".

According to an embodiment of the present disclosure, a "memory" may be implemented as a processor and a memory. The term "processor" should be broadly construed to include general purpose processors, central processing units, microprocessors, digital signal processors, controllers, microcontrollers, state machines, and the like. In some contexts, "processor" may refer to an application specific integrated circuit, programmable logic device, field programmable gate array, or the like. The term "processor" means a combination of processing devices, such as a combination of a digital signal processor and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors combined with a discrete cosine transform core, or Any other combination of such devices.

The term "memory" should be interpreted broadly to include any electronic component capable of storing electronic information. The term memory may refer to various types of processor-readable media such as random access memory, read-only memory, non-volatile random-access memory, programmable read-only memory, erasable programmable read-only memory, electronic Erasable programmable read-only memory, flash memory, magnetic or optical data storage, registers, etc. A memory is said to be in electronic communication with a processor if the processor can read information from and/or write information to the memory. Memory integrated into a processor is in electronic communication with the processor.

Hereinafter, "image" may mean a still image such as a still image of a video or a moving image such as a video (ie, the video itself).

Hereinafter, "sample" refers to data that is assigned to a sampling position of an image and is to be processed. For example, pixel values in an image in the spatial domain or transform coefficients in the transform domain may be samples. A unit including at least one sample may be defined as a block.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present disclosure pertains can easily implement. In addition, in order to clearly describe the present disclosure in the drawings, parts irrelevant to the description are omitted.

Hereinafter, an image encoding device and an image decoding device, an image encoding method, and an image decoding method will be described in detail with reference to FIGS. 1 to 19 . A method of determining a data unit of an image according to an embodiment is described with reference to FIGS. 3 to 16 , and an image encoding or image decoding method and device thereof are described with reference to FIGS. 1-2 and FIGS. 17 to 19 , which are based on the distance to a reference sample point according to an embodiment A filter is determined by at least one of a size of a current block and a size of a current block, and intra prediction is adaptively performed using the determined filter.

Hereinafter, an image encoding/decoding method and apparatus thereof for adaptively performing intra prediction based on coding units of various shapes according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2 .

FIG. 1a is a block diagram of an image decoding device according to various embodiments.

The image decoding device 100 according to various embodiments may include an obtainer 105 , an intra predictor 110 and an image decoder 115 .

The obtainer 105, the intra predictor 110, and the image decoder 115 may include at least one processor. Additionally, the obtainer 105, the intra predictor 110, and the image decoder 115 may include a memory storing instructions to be executed by at least one processor. The image decoder 115 may be implemented in hardware separate from the obtainer 105 and the intra predictor 110 , or may include the obtainer 105 and the intra predictor 110 .

The obtainer 105 may obtain information on transform coefficients of a current block from a bitstream. The obtainer 105 may obtain information on a prediction mode of a current block and information on an intra prediction mode of a current block from a bitstream.

The obtainer 105 may include information indicating that a prediction mode with respect to a current block is an intra prediction mode or an inter prediction mode. The information on the intra prediction mode of the current block may be information on the intra prediction mode applied to the current block among a plurality of intra prediction modes. For example, the intra prediction mode may be one of a DC mode, a planar mode, and at least one angle mode with a prediction direction. The angle pattern may include a horizontal pattern, a vertical pattern, and a diagonal pattern, and may include a pattern having a predetermined direction other than the horizontal direction, the vertical direction, and the diagonal direction. For example, the number of angle patterns can be 65 or 33.

When the prediction mode of the current block is an intra prediction mode, the intra predictor 110 may be activated.

The intra predictor 110 may perform intra prediction on a current block based on an intra prediction mode of the current block. The intra predictor 110 may determine a reference sample for the current sample among the reference samples based on the position of the current sample in the current block and the intra prediction mode of the current block, and may use the A reference sample is used to generate a predicted sample value for the current sample. Here, the reference samples may include samples of a left or upper reference line adjacent to the current block. The reference samples for the current sample may include at least one sample adjacent to the current block among the samples of the reference line on the left or upper of the current block. When there is only one reference sample for the current sample, the intra predictor 110 can use the reference sample to generate the predicted sample value of the current sample. Meanwhile, when there are two or more reference samples for the current sample, the intra predictor 110 may apply a filter to the sample values of the two or more reference samples for the current sample by to generate the predicted sample point of the current sample point. Here, the coefficients of the filter may be integers. In order to determine the coefficients of the filter as integers, scaling is performed on the coefficients of the filter, and the scaled coefficients of the filter may be used. When scaling is performed on the coefficients of the filter and the scaled coefficients of the filter are used, thereafter a process of descaling may be performed according to the degree of scaling of the coefficients of the filter. The accuracy of the filter may be 1/32 fractional pixel accuracy.

The intra predictor 110 may determine a filter for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample. The intra predictor 110 may determine at least one filter candidate applicable to the current sample, and determine at least one filter candidate based on at least one of a distance between the current sample and the reference sample in the current block and a size of the current block. Filter candidate for the current sample. Here, the distance between the current sample point and the reference sample point may be the distance between the current sample point and the reference sample point located in the vertical direction of the current sample point or the distance between the current sample point and the reference sample point located in the horizontal direction of the current block. In this case, the distance between the current sample point and the reference sample point may correspond to the position coordinate value of the current sample point in the current block. Therefore, it can be seen that the intra predictor 110 determines the filter for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample.

The intra prediction unit 110 may determine a type of filter and a coefficient of the filter for the current sample based on at least one of a distance between the current sample and the reference sample in the current block and a size of the current block. Here, the type of filter can be low pass filter, Gaussian filter, bilateral filter, uniform filter, bilinear interpolation filter filter), cubic filter (cubic filter), [1 2 1] filter and discrete cosine transform (Discrete Cosine Transform; DCT) filter (DCT filter). Here, the discrete cosine transform filter may be a 4-tap discrete cosine transform interpolation filter (DCT interpolation filter; DCT-IF) for compensating for sub-pixel motion of the chroma component. In addition, a new filter can be produced by combining two or more filters, and a newly created filter can be added as a filter type. In addition, not limited to the types of filters listed above, various types of The filter may be the type of filter used for the current sample.

The number of taps of the filter for the current sample may be a predetermined value. Here, the predetermined value may be 4, that is, the filter used for the current sample point may be a 4-tap filter, but it is not limited thereto, and the predetermined value may be 1 or greater, preferably 2 or greater. One of the integer values.

Also, the number of taps of the filter for the current sample may be determined based on at least one of the distance between the current sample and the reference sample and the size of the current block. For example, when the distance between the current sample point and the reference sample point is smaller than a predetermined value, the intra predictor 110 may determine the number of taps of the filter as the predetermined number of first taps. When the distance between the current sample point and the reference sample point is greater than a predetermined value, the intra predictor 110 may determine the number of taps of the filter as a predetermined second number of taps. Here, the predetermined number of first taps may be smaller than the predetermined number of second taps.

The intra predictor 110 may determine a plurality of filters for the current block based on at least one of a size of the current block and a distance between at least one sample in the current block and a reference sample. In other words, the plurality of filters for the current block may include at least one filter candidate that may be used for the current sample.

The intra predictor 110 may determine a filter corresponding to a current sample among a plurality of filters for the current block. Here, the intra predictor 110 may be based on the ratio of the size (height or width) of the current block to the distance between at least one sample in the current block and the position of the current sample in the current block (or the distance between the current sample and A distance between samples is referred to) to determine a filter corresponding to a current sample among a plurality of filters for the current block.

The intra predictor 110 may determine first reference samples corresponding to samples in the current block based on the intra prediction mode of the current block. For example, the intra predictor 110 may determine, among the reference samples, a reference sample crossing an extension line from the current sample to the intra prediction direction of the intra prediction mode of the current block as the first reference sample. The intra predictor 110 may determine a plurality of filters for a current block based on a distance between a sample and a first reference sample. The intra predictor 110 may determine a filter corresponding to a current sample among a plurality of filters for the current block.

The intra predictor 110 may determine the number of filters for the current block based on the size of the current block, and determine the filter for the current block corresponding to the number of filters. For example, when the height or width of the current block is smaller than a predetermined value, the image decoding device 100 may determine the number of filters for the current block as one. When the number of filters for the current block is determined to be 1, the intra predictor 110 may determine the filters for the current block based on the size of the current block and the current intra prediction mode. In other words, the intra predictor 110 may determine the critical value based on the size of the current block, and determine the intra prediction mode index difference based on the index difference between the current intra prediction mode and the vertical mode and the horizontal mode, and A filter for the current block is determined by comparing the determined intra prediction mode index difference with a critical value.

In addition, when the value of the index of the intra prediction mode of the current block is an odd value, the intra predictor 110 may determine the first filter as the filter for the current block, and when the value of the intra prediction mode of the current block When the value is even, the second filter may be determined as the filter for the current block.

The intra predictor 110 may determine a range of distances between samples to which each filter is applied and reference samples based on the size of the current block. For example, when the height and width of the current block are both greater than or equal to 32, the distance between the sample point of the current block where the filter f0 is used and the reference sample point may be [0, 2), and the distance between the sample point of the filter f1 is used The distance between the samples of the current block and the reference samples may be [2, 4), and the distance between the samples of the current block where the filter f2 is used and the reference samples may be [4, 8), and The distance between the samples of the current block where the filter f3 is used and the reference samples may be [8, 16), and the distance between the samples of the current block where the filter f4 is used and the reference samples may be [ 16, size). Otherwise, when the height or width of the current block is less than 32, the distance between the sample point of the current block used by filter f0 and the reference sample point may be [0, 1), and the sample point of the current block used by filter f1 The distance between the point and the reference sample can be [1, 2), and the distance between the sample of the current block where the filter f2 is used and the reference sample can be [2, 3), and the filter f3 is The distance between the samples of the current block used and the reference samples may be [3, 4], and the distance between the samples of the current block used by filter f4 and the reference samples may be [4, size) .

The intra predictor 110 may determine a filter for the current sample among filters for the current block based on at least one of a distance between the current sample and the reference sample and a size of the current block.

The intra predictor 110 may further determine a filter to use for the current sample based on at least one of the intra prediction mode of the current block and the shape of the current block.

For example, when the intra prediction mode of the current block is a predetermined intra prediction mode, the intra predictor 110 may base on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block to determine the filter to use for the current sample. Here, the predetermined intra prediction mode may be one of angle modes other than DC mode and planar mode. In detail, the predetermined intra prediction mode may be one of the remaining modes in the angle mode except for the diagonal mode.

For example, when the prediction mode of the current block is the horizontal mode or the vertical mode, the intra predictor 110 may not use any filter (for example, bilinear interpolation filter or [1, 2, 1] reference filter, etc.) to perform intra prediction in order to generate prediction samples for the current block. When the prediction mode of the current block is a diagonal mode with an angle that is a multiple of 45 degrees, the intra predictor 110 may perform intra prediction by using a [1, 2, 1] reference sample filter in order to generate the current block. Prediction samples for the block. When the prediction mode of the current block is an angle mode other than the above modes, the intra predictor 110 may determine based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block. Determines the filter to use for the current sample.

The intra predictor 110 may further determine based on whether the current block is a square or a rectangle, and based on at least one of the distance between the current sample point and the reference sample point in the current block and the size of the current block to determine the point filter.

In addition, the intra predictor 110 may further determine the current block based on the ratio of the height and width of the current block, and based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block. Sample filter.

When the width of the current block is less than or equal to the predetermined first value, and the height of the current block is less than or equal to the predetermined second value, the intra predictor 110 may be based on the distance between the current sample point and the reference sample point in the current block At least one of the distance and the size of the current block is used to determine the first filter for the current sample. In addition, when the width of the current block is greater than a predetermined first value, or the height of the current block is greater than a predetermined second value, the intra predictor 110 may be based on the distance and At least one of the sizes of the current block is used to determine the second filter for the current sample.

When the distance between the current sample point and the reference sample point is less than a predetermined value, the intra predictor 110 may determine the first filter for the current sample point, and when the distance between the current sample point and the reference sample point is greater than the predetermined value , the intra predictor 110 may determine a second filter for the current sample. Here, the smoothing strength of the first filter may be smaller than that of the second filter.

The intra predictor 110 may obtain a predicted block of the current block including predicted samples of the current sample generated using the determined filter.

The image decoder 115 may obtain the residual block of the current block based on the information about the transformation coefficient of the current block. In other words, the image decoder 115 may perform inverse quantization and inverse transformation based on information on the transform coefficient of the current block to obtain residual samples of the residual block of the current block from the bitstream.

The image decoder 115 may restore the current block based on the prediction block of the current block and the residual block of the current block. The image decoder 115 may generate the restoration samples in the current block by using the sample values of the prediction samples in the prediction block of the current block and the sample values of the residual samples in the residual block of the current block, and may A recovery block of the current block is generated based on the recovery samples.

Meanwhile, the image decoding device 100 may determine a filter for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample, and obtain an indication from the bitstream whether to perform the frame adaptively The flag information of the intra prediction may determine whether to determine the filter for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample based on the flag information. Here, flag information can be obtained by block, especially by maximum coding unit. In addition, flag information can be obtained frame by frame.

In addition, the image decoding device 100 can obtain flag information commonly applied to the luminance component and the color difference component. In addition, the image decoding device 100 may obtain flag information respectively applied to the luma component or the color difference component.

The image decoding device 100 may determine a filter set commonly applied to the luma component and the color difference component. In addition, the image decoding device 100 may determine a filter set to be applied by components.

In addition, the image decoding device 100 may determine whether to determine the filter for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample without obtaining the flag information from the bitstream. device. For example, when the prediction mode of the current block is a predetermined intra prediction mode, the image decoding device 100 may determine the current sample point based on at least one of the size of the current block and the distance between the current sample point and the reference sample point filter to determine adaptively perform intra prediction.

In addition, the image decoding device 100 may determine whether to adaptively perform intra prediction based on performing filtering reference samples and a weight value of the filter by using information of adjacent blocks without obtaining flag information from a bitstream. For example, the image decoding apparatus 100 may determine, for a neighboring block of the current block, the filter for the first sample in the neighboring block based on the size of the neighboring block and the distance between the first sample in its neighboring block and the reference sample. filter, and determine whether to determine a filter for the current sample based on at least one of the size of at least one current block and the distance between the current sample and the reference sample based on the flag information of the adjacent block, wherein the adjacent block The flag information indicates whether intra prediction is adaptively performed based on a filter for a first sample in a neighboring block. In addition, when the size of the current block is the size of the predetermined first block, the image decoding device 100 may determine the current sample point based on at least one of the size of the current block and the distance between the current sample point and the reference sample point. , and determine to perform intra prediction based on the filter used for the current sample. When the size of the current block is the size of the predetermined second block, the image decoding device 100 may determine the filter for the current sample not based on the size of the current block and the distance between the current sample and the reference sample. Existing intra prediction is performed in the case.

The image decoding device 100 may determine the filter for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample, and may determine the filter for the current sample based on the intra frame for the current sample. A predictive encoding/decoding tool and a similar intra-frame predictive encoding/decoding tool are combined with each other to perform intra-frame prediction. In addition, the image decoding device 100 may give priority among a plurality of intra-predicted encoding/decoding tools, and may perform intra prediction according to the priority among the encoding/decoding tools. In other words, when an encoding/decoding tool with high priority is used, an encoding/decoding tool with low priority may not be used, and when an encoding/decoding tool with high priority is not used, an encoding/decoding tool with low priority may be used Level encoding/decoding tools.

Fig. 1b illustrates a flowchart of an image decoding method according to various embodiments.

In operation S105, the image decoding device 100 may obtain information about a transform coefficient of a current block from a bitstream.

In operation S110, the image decoding device 100 may determine a filter for the current sample based on at least one of a distance between the current sample and the reference sample in the current block and a size of the current block.

In operation S115, the image decoding device 100 may obtain a predicted block of the current block including predicted samples of the current sample generated by using the determined filter.

In operation S120, the image decoding device 100 may obtain a residual block of the current block based on the information about the transformation coefficient of the current block.

In operation S125, the image decoding device 100 may restore the current block based on the prediction block and the residual block of the current block.

Fig. 1c illustrates a block diagram of an image decoder 6000 according to various embodiments.

The image decoder 6000 according to various embodiments performs operations performed when image data is decoded by the image decoder 115 of the image decoding device 100 .

Referring to FIG. 1c , an entropy decoder 6150 parses encoded image data to be decoded and encoding information required for decoding from a bitstream 6050 . The encoded image data are quantized transform coefficients. The inverse quantizer 6200 and the inverse transformer 6250 restore residual data from quantized transform coefficients.

The intra predictor 6400 performs intra prediction per block. The intra predictor 6400 of FIG. 1c may correspond to the intra predictor 110 of FIG. 1A.

The inter predictor 6350 performs inter prediction by using a reference image obtained from the restored picture buffer 6300 by block. The data of the spatial domain for the block of the current image may be restored by adding the prediction data and residual data for each block generated by the intra predictor 6400 or the inter predictor 6350, and the deblocking unit 6450 and The sample adaptive offset performer 6500 may output a filtered restored image 6600 by performing in-loop filtering on the restored spatial domain data. Also, the restored image stored in the restored picture buffer 6300 may be output as a reference image.

In order for a decoder (not shown) of the image decoding device 100 to decode image data, the stepwise operation of the image decoder 6000 according to various embodiments may be performed block by block.

FIG. 1d illustrates a block diagram of an image decoding device 100 according to an embodiment.

The image decoding device 100 according to an embodiment may include a memory 120 and at least one processor 125 connected to the memory 120 . The operation of the image decoding device 100 according to the embodiment may operate as a separate processor, or may operate under the control of a central processor. In addition, the memory 120 of the image decoding device 100 may store data received from the outside and data generated by the processor. The processor 125 of the image decoding device 100 may obtain information about the current block from the bitstream, and determine the information for the current block based on at least one of the distance between the current sample point and the reference sample point in the current block and the size of the current block. and obtaining a prediction block of the current block including a prediction sample of the current sample generated using the determined filter, and obtaining a residual block of the current block based on information about a transform coefficient of the current block, And the current block is restored based on the prediction block and the residual block of the current block.

Fig. 2a illustrates a block diagram of an image encoding device according to various embodiments.

The image encoding device 150 according to various embodiments may include an intra predictor 155 and an image encoder 160 .

The intra predictor 155 and the image encoder 160 may include at least one processor. In addition, the intra predictor 155 and the image encoder 160 may include a memory storing instructions to be executed by at least one processor. Realized by hardware other than the intra predictor 155 and the image encoder 160 , or may include the intra predictor 155 and the image encoder 160 .

The intra predictor 155 may determine a filter for the current sample based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block.

The intra predictor 155 may generate a prediction block of a current block including a prediction sample of a current sample generated using a filter for the current sample.

The intra predictor 155 may determine a type of filter and a coefficient of the filter for the current sample based on at least one of a distance between the current sample and the reference sample in the current block and the size of the current block.

The number of taps of the filter for the current sample may be a predetermined value. Here, the predetermined value may be an integer of 4 or more. Also, the number of taps of the filter for the current sample may be determined based on at least one of the distance between the current sample and the reference sample and the size of the current block.

The intra predictor 155 may determine a plurality of filters for the current block based on at least one of the size of the current block and the distance between the samples in the current block and the reference samples.

The intra predictor 155 may determine a filter corresponding to a current sample among a plurality of filters for the current block.

The intra predictor 155 may determine first reference samples corresponding to samples in the current block based on the intra prediction mode of the current block. The intra predictor 155 may determine a plurality of filters for a current block based on a distance between samples in the current block and a first reference sample. The intra predictor 155 may determine a filter corresponding to a current sample among a plurality of filters for the current block.

The intra predictor 155 may determine the number of filters for the current block based on the size of the current block, and determine the filters for the current block corresponding to the filter number, and the intra predictor 155 may determine the number of filters for the current block based on the size of the current block. The filter for the current sample is determined among the filters for the current block by at least one of the distance between the point and the reference sample and the size of the current block.

When the intra prediction mode of the current block is a predetermined intra prediction mode, the intra predictor 155 may determine based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block The filter to use for the current sample.

When the distance between the current sample point and the reference sample point is less than a predetermined value, the intra predictor 155 can determine the first filter for the current sample point, and when the distance between the current sample point and the reference sample point is greater than When is a predetermined value, the intra predictor 110 may determine a second filter for the current sample. Here, the smoothing strength of the first filter may be smaller than that of the second filter.

The image encoder 160 may encode information about transformation coefficients of a current block based on a prediction block of the current block. In other words, the image encoder 160 may generate a residual block of the current block based on the original block of the current block and the prediction block of the current block, and transform the transform coefficient of the current block by transforming and quantizing the residual block of the current block. information is encoded. The image encoder 160 may encode information on the prediction mode of the current block and information on the intra prediction mode of the current block.

The image encoder 160 may generate a bitstream including information on transform coefficients of a current block, and output the bitstream.

Fig. 2b is a flowchart of an image encoding method according to various embodiments.

In operation S150, the image encoding device 150 may determine a filter for the current sample based on at least one of the distance between the current sample and the reference sample and the size of the current block.

In operation S155, the image encoding device 150 may generate a predicted block of the current block including prediction samples of the current sample generated using the determined filter. In operation S160, the image encoding device 150 may encode information about the transformation coefficient of the current block based on the prediction block of the current block.

Fig. 2c illustrates a block diagram of an image encoder according to various embodiments.

The image encoder 7000 according to various embodiments performs operations performed when image data is decoded by the image encoder 160 of the image encoding device 150 .

In other words, the intra predictor 7200 performs intra prediction on the current image 7050 by block, and the inter predictor 7150 performs frame prediction by using the current image 7050 and the reference image obtained from the restored picture buffer 7100 by block. time forecast.

The residual data may be generated by subtracting the prediction data for each block output from the intra predictor 7200 or the inter predictor 7150 from the data for the encoded block of the current image 7050, and the transformer 7250 The sum quantizer 7300 may output transform coefficients quantized by blocks by performing transform and quantization on residual data. The intra predictor 7200 of FIG. 2c may correspond to the intra predictor 155 of FIG. 2A.

The inverse quantizer 7450 and the inverse transformer 7500 may restore residual data of the spatial domain by performing inverse quantization and inverse transformation on quantized transform coefficients. The restored residual data of the spatial domain may be added to the prediction data for each block output from the intra predictor 7200 or the inter predictor 7150 to be restored as the residual data of the spatial domain for the block of the current image 7050. data. The deblocking unit 7550 and the SAO performer generate a filtered restored image by performing in-loop filtering on the restored spatial domain data. The generated restored image is stored in the restored picture buffer 7100 . A restored image stored in the restored picture buffer 7100 may be used as a reference image for inter prediction of another image. The entropy encoder 7350 may entropy-encode the quantized transform coefficients, and the entropy-encoded coefficients may be output as a bitstream 7400 .

In order for the image encoder 7000 according to various embodiments to be applied to the image encoding device 150, the stepwise operation of the image encoder 7000 according to various embodiments may be performed block by block.

FIG. 2d is a block diagram of an image encoding device 150 according to an embodiment.

The image encoding device 150 according to an embodiment may include a memory 165 and at least one processor 170 connected to the memory 170 . The operation of the image encoding device 150 according to the embodiment may operate as a separate processor, or may operate according to the control of the central processor. In addition, the memory 165 of the image encoding device 150 may store data received from the outside and data generated by the processor.

The processor 170 of the image encoding device 150 may determine a filter for the current sample based on at least one of the distance between the current sample in the current block and the reference previous sample and the size of the current block, and generate the filter using The determined filter is used to generate the prediction block of the current block of the prediction sample of the current sample point, and the information about the transformation coefficient of the current block is encoded based on the prediction block of the current block.

Hereinafter, division of coding units will be described in detail according to an embodiment of the present disclosure.

First, a picture (Picture) can be divided into one or more slices. A slice may be a sequence of one or more largest coding units (Coding Tree Unit; CTU). A concept in contrast to the largest coding unit (CTU) is the largest coding block (Coding Tree Block; CTB).

A largest coding block (CTB) refers to an NxN block including NxN samples (N is an integer). Each color component can be divided into one or more maximal coding blocks.

When a picture has three sample arrays (sample arrays by Y, Cr, and Cb components), the largest coding unit (CTU) is the largest coding block including luma samples and two blocks of corresponding chrominance samples. The largest coding block, the unit of the syntax structure used to encode luma samples and chroma samples. When the picture is a monochrome picture, the LCU is a unit including the largest coding block of a monochrome sample and a syntax structure for encoding the monochrome sample. When a picture is a picture encoded with color planes separated for each color component, the maximum coding unit is a unit including a syntax structure for encoding the corresponding picture and samples of the picture.

One maximum coding block (CTB) may be divided into MxN coding blocks (coding blocks) including MxN samples (M and N are integers).

When a picture has an array of samples according to Y, Cr and Cb components, a coding unit (Coding Unit; CU) is a coding block including luma samples and two coding blocks corresponding to chrominance samples, used for Syntax structure for encoding luma and chroma samples. When the picture is a monochrome picture, the coding unit is a unit including a coding block of monochrome samples and a syntax structure for coding the monochrome samples. When a picture is a picture in which color planes separated for each color component are coded, a coding unit is a unit including a corresponding picture and a syntax structure for coding samples of the picture.

As described above, the largest coding block and the largest coding unit are concepts different from each other, and the coding block and the coding unit are concepts different from each other. In other words, a (largest) coding unit refers to a (largest) coding block including corresponding samples and a data structure including a syntax structure corresponding thereto. However, those of ordinary skill in the art can understand that a (largest) coding unit or (largest) coding block refers to a block of a predetermined size including a predetermined number of samples, so in the following description, the largest coding block and the largest coding unit , or coding blocks and coding units are referred to without distinction unless otherwise stated.

An image may be divided into a largest coding unit (Coding Tree Unit; CTU). The size of the maximum coding unit may be determined based on information obtained from a bitstream. The shape of the maximum coding unit may have the same size as a square, but is not limited thereto.

For example, information about the maximum size of a luma-encoded block can be obtained from the bitstream. For example, the maximum size of the luma coding block indicated by the information on the maximum size of the luma coding block may be one of 16×16, 32×32, 64×64, 128×128, and 256×256.

For example, information about the difference between the maximum size of a luma encoding block that can be divided into two and the size of a luma block may be obtained from a bitstream. Information about a difference in luma block size may indicate a difference in size between a luma maximum coding unit and a maximum luma coding block capable of being divided into two. Accordingly, the size of a luma maximum coding unit may be determined when combining information on a maximum size of a luma coding block that can be divided into two obtained from a bitstream and information on a difference in luma block size. When the size of the luma largest coding unit is used, the size of the chroma largest coding unit may be determined. For example, when the ratio according to the color format Y:Cb:Cr is 4:2:0, the size of a chroma block may be half the size of a luma block, and similarly, the size of a chroma largest coding unit may be the size of a luma largest half of the coding unit.

According to an embodiment, information on the maximum size of a luma encoding block capable of binary splitting is obtained from a bitstream, and thus the maximum size of a luma encoding block capable of binary splitting may be variably determined. In contrast to this, the maximum size of a luma encoding block capable of ternary split may be fixed. For example, the maximum size of a luma coding block capable of three-partitioning in an I slice may be 32×32, and the maximum size of a luma coding block capable of three-partitioning in a P slice or a B slice may be 64×64 .

Also, the maximum coding unit may be hierarchically split into coding units based on split shape pattern information obtained from a bitstream. As the division shape mode information, at least one of information indicating whether to perform quadsplit, information indicating whether to perform multiple split, information indicating a direction of division, and information of a division type can be obtained from the bitstream.

For example, the information indicating whether to quad split (quad split) may indicate whether the current coding unit is quad split (QUAD_SPLIT).

When the current coding unit is not split by four, the information indicating whether the current coding unit is multiple-split may indicate whether the current coding unit is no longer split (NO_SPLIT) or split by two/three.

When the current coding unit is divided into two or three, the split direction information indicates that the current coding unit is split in a horizontal direction or a vertical direction.

When the current coding unit is split in a horizontal or vertical direction, the split type information indicates that the current coding unit is split by two or three.

According to the division direction information and the division type information, the division mode of the current coding unit can be determined. The division mode when the current coding unit is divided into two in the horizontal direction may be determined as two horizontal divisions (SPLIT_BT_HOR), three horizontal divisions (SPLIT_TT_HOR) when the current coding unit is divided into three in the horizontal direction, and three horizontal divisions (SPLIT_TT_HOR) when it is divided into two in the vertical direction. The division pattern may be determined as two vertical divisions (SPLIT_BT_VER), and the division mode when divided by three in a vertical direction may be determined as three vertical divisions (SPLIT_BT_VER).

The image decoding device 100 can obtain division form mode information from a binary string (binstring) in a bitstream. The shape of the bit stream received by the image decoding device 100 may include fixed length binary code (Fixedlength binary code), unary code (Unary code), truncated unary code (Truncated unary code), predetermined binary code, and the like. Binary strings indicate information by arranging binary digits. A binary string may consist of at least one bit. The image decoding device 100 may obtain division form pattern information corresponding to a binary string based on division rules. The image decoding device 100 may determine whether to divide the coding unit into four, whether not to divide, or a division direction and a division type based on one binary string.

A coding unit may be smaller than or equal to a maximum coding unit. For example, the largest coding unit is a coding unit having the largest size, and the largest coding unit is also one of the coding units. When the split shape mode information on the split form mode indicates that splitting is not performed, the coding unit determined in the maximum coding unit has the same size as the size of the maximum coding unit. When the split form mode information on the maximum coding unit indicates splitting, the maximum coding unit may be split into coding units. And, when splitting is indicated for the split form mode information on the coding unit, the coding unit may be split into coding units whose size is smaller. However, division of an image is not limited thereto, and a maximum coding unit and a coding unit may not be distinguished. The division of coding units is described in more detail in FIGS. 3 to 16 .

Also, one or more prediction blocks used for prediction may be determined from the coding unit. A predicted block may be equal to or smaller than a coding unit. Also, one or more transform blocks for transform may be determined from the coding unit. A transform block may be equal to or smaller than a coding unit.

The shapes and sizes of the transform block and the prediction block may not be correlated with each other.

According to another embodiment, a coding unit may perform prediction by using the coding unit as a prediction block. Also, the coding unit may perform transformation by using the coding unit as a transformation block.

The division of coding units is described in more detail in FIGS. 3 to 16 . The current block and neighboring blocks of the present disclosure may indicate one of a maximum coding unit, a coding unit, a prediction block, and a transformation block. And, the current block or the current coding unit is a block currently being decoded or coded or a block currently being divided. Neighboring blocks may be restored blocks prior to the current block. Neighboring blocks may be spatially or temporally adjacent to the current block. The neighboring block may be located in one of lower left, left, upper left, upper, upper right, right, and lower right of the current block.

FIG. 3 illustrates a process in which the image decoding device 100 divides a current coding unit to determine at least one coding unit, according to an embodiment.

Block shapes may include 4Nx4N, 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN, or Nx8N. Here, N may be a positive integer. The block shape information is information indicating at least one of a shape, a direction, a width-to-height ratio, and a size of a coding unit.

The shape of the coding unit may include square and non-square. When the width and height of the coding unit are the same size (ie, when the block shape of the coding unit is 4N×4N), the image decoding device 100 may determine the block shape information of the coding unit as a square. The image decoding device 100 may determine the shape of the coding unit to be non-square.

When the size of the width and height of the coding unit is different (that is, when the block shape of the coding unit is 4N×2N, 2N×4N, 4N×N, N×4N, 32N×N, N×32N, 16N×N, N× 16N, 8N×N or N×8N), the image decoding device 100 may determine the block shape information of the coding unit as non-square. When the shape of the coding unit is non-square, the image decoding device 100 may determine the ratio of the width to the height in the block shape information of the coding unit as 1:2, 2:1, 1:4, 4:1, 1:8, 8 :1, 1:16, 16:1, 1:32, 32:1 at least one. And, based on the magnitude of the width and the magnitude of the height of the coding unit, the image decoding device 100 may determine whether the coding unit is in a horizontal direction or a vertical direction. And, based on at least one of the size of the width, the size of the height, and the area of the coding unit, the image decoding device 100 may determine the size of the coding unit.

According to an embodiment, the image decoding device 100 may determine the shape of the coding unit using block shape information, and may determine in which form the coding unit is split using split form mode information. In other words, the division method of the coding unit indicated by the division form mode information may be determined according to which block shape is indicated by the block shape information used by the image decoding device 100 .

The image decoding device 100 may obtain division shape pattern information from a bitstream. However, it is not limited thereto, and the image decoding device 100 and the image encoding device 150 may determine predetermined division shape pattern information based on block shape information. The image decoding device 100 may determine split shape pattern information predetermined for a maximum coding unit or a minimum coding unit. For example, for the LCU, the image decoding device 100 may determine the split form mode information as a quad split. And, for the minimum coding unit, the image decoding device 100 may determine the division form mode information as "no division". Specifically, the image decoding device 100 may determine the size of the largest coding unit as 256×256. The image decoding device 100 may determine predetermined division shape pattern information as four divisions. The quad partition is a partition form pattern that halves both the width and the height of the coding unit. The image decoding device 100 may obtain a coding unit having a size of 128×128 from a maximum coding unit having a size of 256×256 based on the split shape mode information. In addition, the image decoding device 100 may determine the size of the minimum coding unit as 4x4. The image decoding device 100 may obtain split form mode information indicating "no split" for the minimum coding unit.

According to an embodiment, the image decoding apparatus 100 may use block shape information indicating that a current coding unit has a square shape. For example, the image decoding device 100 may determine whether to divide a square coding unit into four coding units, vertically, horizontally, or not, according to the division form mode information. Referring to FIG. 3 , when the block shape information of the current coding unit 300 shows a square shape, the decoder 120 may not split the coding unit 310a having the same size as the current coding unit 300 based on the split form pattern information indicating not to be split, or may Coding units 310 b , 310 c , 310 d , 310 e , and 310 f , etc., which are split based on split form pattern information indicating a predetermined splitting manner are determined.

Referring to FIG. 3 , the image decoding device 100 may divide the current coding unit 300 in a vertical direction to determine two coding units 310 b based on the division form mode information indicating division in the vertical direction according to an embodiment. The image decoding device 100 may determine two coding units 310c to split the current coding unit 300 in the horizontal direction based on the split form pattern information indicating splitting in the horizontal direction. The image decoding device 100 may determine the four coding units 310d in which the current coding unit 300 is split vertically and horizontally based on the split form pattern information indicating that the coding unit is split vertically and horizontally. According to an embodiment, the image decoding device 100 may determine three coding units 310 e in which the current coding unit 300 is vertically split by based on split shape pattern information indicating that the coding unit is vertically split into ternary. The image decoding device 100 may determine the three coding units 310f that divide the current coding unit 300 in the horizontal direction by based on the split shape pattern information indicating that the coding unit is split into three in the horizontal direction. However, division forms that may be used to divide a square coding unit should not be construed as being limited to the above-mentioned forms, but may include various forms that can be indicated by the division form pattern information. A predetermined splitting form of splitting a square coding unit is specifically described below with reference to various embodiments.

FIG. 4 illustrates a process in which the image decoding device 100 divides non-square-shaped coding units to determine at least one coding unit, according to an embodiment.

According to an embodiment, the image decoding device 100 may use block shape information indicating that a current coding unit has a non-square shape. The image decoding device 100 may determine whether to divide the non-square current coding unit or divide the current coding unit in a predetermined method based on the division form mode information. Referring to FIG. 4 , when the block shape information of the current coding unit 400 or 450 indicates a non-square shape, the image decoding device 100 may determine a block having the same size as the current coding unit 400 or 450 according to the division form mode information indicating no division. The size of the coding unit 410 or 460, or the split coding units 420a, 420b, 430a, 430b, 430c, 470a, 470b, 480a, 480b, and 480c may be determined based on split form mode information indicating a predetermined split method. A predetermined division method of dividing a non-square coding unit is specifically described below with reference to various embodiments.

According to an embodiment, the image decoding device 100 may determine a form of splitting a coding unit using split-form pattern information, and in this case, the split-form pattern information may indicate the number of at least one coding unit generated by splitting the coding unit. Referring to FIG. 4 , when the division form mode information indicates that the current coding unit 400 or 450 is divided into two coding units, the image decoding device 100 may divide the current coding unit 400 or 450 based on the division form mode information to determine that the current coding unit includes The two encoding units 420a, 420b or 470a, 470b of .

According to an embodiment, when the image decoding device 100 divides the non-square current coding unit 400 or 450 based on the division form mode information, the image decoding device 100 may consider the position of the long side of the non-square current coding unit 400 or 450 to determine Divide the current coding unit. For example, the image decoding device 100 may determine a plurality of coding units by dividing the current coding unit 400 or 450 in a direction of dividing a long side of the current coding unit 400 or 450 in consideration of a shape of the current coding unit 400 or 450 .

According to an embodiment, when the split form mode information indicates that the coding unit is split (ternary split) into an odd number of blocks, the image decoding device 100 may determine an odd number of coding units included in the current coding unit 400 or 450 . For example, when the division mode information indicates that the current coding unit 400 or 450 is divided into three coding units, the image decoding device 100 may divide the current coding unit 400 or 450 into three coding units 430a, 430b and 430c or 480a, 480b , 480c.

According to an embodiment, the ratio of the width to the height of the current coding unit 400 or 450 may be 4:1 or 1:4. When the ratio of the width to the height is 4:1, since the width is greater than the height, the block shape information may be in the horizontal direction. When the ratio of the width to the height is 1:4, since the size of the width is shorter than the size of the height, the block shape information may be in the vertical direction. The image decoding device 100 may determine to split the current coding unit into an odd number of blocks based on the split form mode information. And, the image decoding device 100 may determine a splitting direction of the current coding unit 400 or 450 based on the block shape information of the current coding unit 400 or 450 . For example, when the current coding unit 400 is in the vertical direction, the image decoding device 100 may determine the coding units 430a, 430b, and 430c by dividing the current coding unit 400 in the horizontal direction. In addition, when the current coding unit 450 is in the horizontal direction, the image decoding device 100 may determine the coding units 480a, 480b, and 480c by dividing the current coding unit in the vertical direction.

According to an embodiment, the image decoding device 100 may determine an odd number of coding units included in the current coding unit 400 or 450 , and the sizes of the determined coding units are not necessarily the same. For example, the size of the predetermined coding unit 430b or 480b among the determined odd coding units 430a, 430b, 430c, 480a, 480b and 480c may be different from the size of other coding units 430a, 430c, 480a and 480c. In other words, a coding unit that may be determined by splitting the current coding unit 400 or 450 may have multiple types of sizes, and each of the odd coding units 430a, 430b, 430c, 480a, 480b, and 480c may have a different size according to circumstances.

According to an embodiment, when the division form mode information indicates that the coding unit is divided into an odd number of blocks, the image decoding device 100 may determine an odd number of coding units included in the current coding unit 400 or 450, and further, the image decoding device 100 may A predetermined restriction is imposed on at least one coding unit among the odd coding units generated by the split. Referring to FIG. 4 , the image decoding device 100 may make the decoding process of the centrally located coding units 430b and 480b among the three coding units 430a, 430b, and 430c or 480a, 480b, and 480c generated by dividing the current coding unit 400 or 450 be the same as The decoding process for other coding units 430a, 430c, 480a, and 480c is different. For example, unlike the other coding units 430a, 430c, 480a, and 480c, the image decoding device 100 may restrict the centrally located coding units 430b and 480b from being divided any more or only a predetermined number of times.

FIG. 5 illustrates a process in which the image decoding device 100 splits a coding unit based on at least one of block shape information and split form mode information according to an embodiment.

According to an embodiment, the image decoding device 100 may determine to divide the square-shaped first coding unit 500 into a plurality of coding units or determine not to divide based on at least one of the block shape information and the division form mode information. According to an embodiment, when the division form mode information indicates that the first coding unit 500 is divided in the horizontal direction, the image decoding device 100 may determine the second coding unit 510 by dividing the first coding unit 500 in the horizontal direction. The first coding unit, the second coding unit, and the third coding unit used according to an embodiment are terms used for understanding the division context between coding units. For example, the second coding unit may be determined by dividing the first coding unit, and the third coding unit may be determined by dividing the second coding unit. In the following, it can be understood that the relationship among the first coding unit, the second coding unit and the third coding unit used is based on the above characteristics.

According to an embodiment, the image decoding device 100 may determine to divide the determined second coding unit 510 into a plurality of coding units or determine not to divide based on the division form mode information. Referring to FIG. 5 , the image decoding device 100 may divide the non-square-shaped second coding unit 510 determined by dividing the first coding unit 500 into at least one third coding unit 520a, 520b, 520c, and 520d, etc., based on the division form mode information. Or the second coding unit 510 is not divided. The image decoding device 100 may obtain split form mode information, and may divide the first coding unit 500 into a plurality of second coding units (for example, 510) of various forms based on the obtained split form mode information, and the second The coding unit 510 may be split according to the manner in which the first coding unit 500 is split based on the split form mode information. According to an embodiment, when the first coding unit 500 is divided into the second coding unit 510 based on the division mode information about the first coding unit 500 , the second coding unit 510 may also be based on the division of the second coding unit 510 The format mode information is divided into third coding units (eg, 520a, 520b, 520c, and 520d, etc.). In other words, coding units may be recursively split based on split form pattern information related to each coding unit. Therefore, the square coding unit may be determined among the non-square-shaped coding units, and the non-square-shaped coding unit may also be determined by recursively dividing the square-shaped coding unit.

Referring to FIG. 5 , predetermined coding units (for example, centrally located coding units or square-shaped coding units) among odd-numbered third coding units 520b, 520c, and 520d determined by dividing a non-square-shaped second coding unit 510 coding unit) can be recursively divided. According to an embodiment, the square third coding unit 520b, which is one of the odd number of third coding units 520b, 520c, and 520d, may be divided in a horizontal direction and divided into a plurality of fourth coding units. The non-square-shaped fourth coding unit 530b or 530d of one of the plurality of fourth coding units 530a, 530b, 530c, and 530d may be further divided into a plurality of coding units. For example, the non-square fourth coding unit 530b or 530d may be further divided into an odd number of coding units. A method that may be used to recursively divide a coding unit is described later through various embodiments.

According to an embodiment, the image decoding device 100 may divide the third coding units 520 a , 520 b , 520 c , and 520 d into a plurality of coding units, respectively, based on the division form mode information. And, the image decoding device 100 may determine not to split the second coding unit 510 based on the split form mode information. The image decoding device 100 may divide the non-square second coding unit 510 into an odd number of third coding units 520b, 520c, and 520d according to an embodiment. The image decoding device 100 may implement a predetermined restriction on a predetermined number of third coding units among the odd-numbered third coding units 520b, 520c, and 520d. For example, the image decoding device 100 may limit the centrally located coding unit 520c among the odd-numbered third coding units 520b, 520c, and 520d to be no longer divided or may be divided a configurable number of times.

Referring to FIG. 5 , the image decoding device 100 may restrict the centrally located coding unit 520c among the odd-numbered third coding units 520b, 520c, and 520d included in the non-square-shaped second coding unit 510 from being divided any more, restricting the division. form (for example, only be divided into four coding units or be divided in a form corresponding to the form in which the second coding unit 510 is divided), or limit the number of divisions (for example, only divide n times, n>0) . However, the restriction on the centrally located encoding unit 520c is merely an example, and should not be construed as being limited to the above-described embodiments, but should be interpreted as including that the centrally located encoding unit 520c can be decoded to be compatible with other encoding units 520b Various restrictions different from 520d.

According to an embodiment, the image decoding device 100 may obtain division form mode information for dividing the current coding unit from a predetermined position within the current coding unit.

FIG. 6 illustrates a method of determining a predetermined coding unit from an odd number of coding units by the image decoding device 100 according to an embodiment.

Referring to FIG. 6 , the division form mode information of the current coding units 600 and 650 may be samples located at predetermined positions (for example, samples 640 and 690 located at the center) among a plurality of samples included in the current coding units 600 and 650. )acquired. However, the predetermined position within the current coding unit 600 where at least one of such division form mode information can be obtained should not be limitedly interpreted as the central position shown in FIG. Various positions within the current coding unit 600 (eg, uppermost, lowermost, left, right, upper left, lower left, upper right, lower right, etc.). The image decoding device 100 may obtain split form mode information obtained from a predetermined location to determine to split the current coding unit into coding units of various shapes and sizes or to determine not to split.

According to an embodiment, when the current coding unit is divided into a predetermined number of coding units, the image decoding device 100 may select one of the coding units. There may be various methods of selecting one from a plurality of coding units, which are described later with reference to various embodiments below.

According to an embodiment, the image decoding device 100 may divide a current coding unit into a plurality of coding units and determine a coding unit at a predetermined location.

According to an embodiment, the image decoding device 100 may use information indicating respective positions of odd coding units to determine a centrally located coding unit among the odd coding units. Referring to FIG. 6 , the image decoding device 100 may divide the current coding unit 600 or the current coding unit 650 to determine an odd number of coding units 620a, 620b, and 620c or an odd number of coding units 660a, 660b, and 660c. The image decoding device 100 may determine the central coding unit 620b or the central coding unit 660b using information on the positions of the odd coding units 620a, 620b, and 620c or the odd coding units 660a, 660b, and 660c. For example, the image decoding device 100 may determine positions of the encoding units 620a, 620b, and 620c based on information indicating positions of predetermined samples included in the encoding units 620a, 620b, and 620c to determine the centrally located encoding unit 620b. Specifically, the image decoding device 100 may determine the positions of the coding units 620a, 620b, and 620c based on the information indicating the positions of the samples 630a, 630b, and 630c at the left upper ends of the coding units 620a, 620b, and 620c to determine the centrally located coding units 620a, 620b, and 620c. Unit 620b.

According to an embodiment, the information indicating the positions of the upper left samples 630a, 630b, and 630c respectively included in the encoding units 620a, 620b, and 620c may include information about the positions or coordinates of the encoding units 620a, 620b, and 620c within the picture. Information. According to an embodiment, the information indicating the positions of the samples 630a, 630b, and 630c at the upper left end respectively included in the coding units 620a, 620b, and 620c may include indicating the coding units 620a, 620b, and Information about the width or height of 620c, which may be equivalent to information indicating the difference between the coordinates of the encoding units 620a, 620b, and 620c within the frame. That is, the image decoding device 100 may directly use information about the positions or coordinates of the coding units 620a, 620b, and 620c within the screen or use information about the width or height of the coding units corresponding to the difference between the coordinates to determine The centrally located encoding unit 620b.

According to an embodiment, the information indicating the position of the sample point 630a at the upper left end of the upper encoding unit 620a may indicate (xa, ya) coordinates, and the information indicating the position of the sample point 630b at the upper left end of the central encoding unit 620b may indicate (xb, yb) coordinates, the information indicating the position of the sample point 630c at the left upper end of the lower encoding unit 620c may indicate (xc, yc) coordinates. The image decoding device 100 may determine the central coding unit 620b using coordinates of upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c, respectively. For example, by arranging the coordinates of the sample points 630a, 630b, and 630c at the upper left end in ascending or descending order, the encoding unit 620b including the coordinates (ie (xb, yb)) of the sample point 630b located in the center may be determined to be the A centrally located CU among the CUs 620 a , 620 b , and 620 c determined by dividing the current CU 600 . However, the coordinates indicating the positions of the samples 630a, 630b, and 630c at the upper left end may refer to coordinates indicating an absolute position within the screen, and further, the sample point 630b which indicates the upper left end of the central encoding unit 620b may be used relative to The (dxb, dyb) coordinates of the information of the relative position of the sample point 630a on the left upper end of the upper end encoding unit 620a and the left upper end sample point 630c indicating the left upper end of the lower end encoding unit 620c relative to the left side of the upper end encoding unit 620a (dxc, dyc) coordinates of the relative position information of the sample point 630a at the upper end of the side. And, a method of determining a coding unit of a predetermined position by using information indicating a position of a sample included in the coding unit as the coordinates of the sample should not be construed as being limited to the above-mentioned method, but can be interpreted as using Various arithmetic methods for the coordinates of sample points.

According to an embodiment, the image decoding device 100 may divide the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c, and may determine the coding units from the coding units 620a, 620b, and 620c according to a predetermined standard. For example, the image decoding device 100 may select a coding unit 620b having a different size from among the coding units 620a, 620b, and 620c.

According to an embodiment, the image decoding device 100 may use (xa, ya) coordinates as information indicating the position of the sample point 630a at the upper left end of the upper encoding unit 620a as the sample point indicating the upper left end of the central encoding unit 620b. The (xb, yb) coordinates of the information on the position of 630b) and the (xc, yc) coordinates of the information indicating the position of the sample point 630c at the left upper end of the lower end encoding unit 620c are used to determine the respective encoding units 620a, 620b, and 620c. width and height. The image decoding device 100 may determine respective sizes of the coding units 620a, 620b, and 620c using coordinates (xa, ya), (xb, yb), and (xc, yc) indicating locations of the coding units 620a, 620b, and 620c. According to an embodiment, the image decoding device 100 may determine the width of the upper coding unit 620 a as the width of the current coding unit 600 . The image decoding device 100 may determine the height of the upper coding unit 620a as yb-ya. According to an embodiment, the image decoding device 100 may determine the width of the central coding unit 620 b as the width of the current coding unit 600 . The image decoding device 100 may determine the height of the central coding unit 620b as yc-yb. According to an embodiment, the image decoding device 100 may use the width or height of the current CU and the width and height of the upper CU 620a and the central CU 620b to determine the width or height of the lower CU. The image decoding device 100 may determine a coding unit having a size different from that of other coding units based on the determined width and height of the coding units 620a, 620b, and 620c. Referring to FIG. 6 , the image decoding device 100 may determine a central coding unit 620b having a size different from that of an upper coding unit 620a and a lower coding unit 620c as a coding unit at a predetermined position. However, the process of the image decoding device 100 determining a size different from that of other coding units is only an embodiment of determining a coding unit at a predetermined position using the size of the coding unit determined based on the sample point coordinates, so the Various processes for determining the coding unit at the predetermined position by comparing the size of the coding unit determined according to the predetermined sample point coordinates.

The image decoding device 100 may use (xd, yd) coordinates) as information indicating the position of the sample point 670a at the left upper end of the left encoding unit 660a, as the position of the sample point 670b indicating the left upper end of the central encoding unit 660b The (xe, ye) coordinates of the information and the (xf, yf) coordinates as information indicating the position of the sample point 670c at the left upper end of the right encoding unit 660c determine the respective widths or heights of the encoding units 660a, 660b, and 660c . The image decoding device 100 may determine the size of each coding unit 660a, 660b, and 660c using (xd, yd), (xe, ye), and (xf, yf), which are coordinates indicating positions of the coding units 660a, 660b, and 660c .

According to an embodiment, the image decoding device 100 may determine the width of the left coding unit 660a as xe-xd. The image decoding device 100 may determine the height of the left coding unit 660 a as the height of the current coding unit 650 . According to an embodiment, the image decoding device 100 may determine the width of the central coding unit 660b as xf-xe. The image decoding device 100 may determine the height of the central coding unit 660 b as the height of the current coding unit 600 . According to an embodiment, the image decoding device 100 may determine the width or height of the right coding unit 660c using the width or height of the current coding unit 650 and the width and height of the left coding unit 660a and the central coding unit 660b. The image decoding device 100 may determine a coding unit having a size different from that of other coding units based on the determined width and height of the coding units 660a, 660b, and 660c. Referring to FIG. 6 , the image decoding device 100 may determine a central coding unit 660b having a size different from those of the left coding unit 660a and the right coding unit 660c as a predetermined location coding unit. However, the process of the image decoding device 100 determining a coding unit having a size different from that of other coding units is only one embodiment of using the size of the coding unit determined based on the sample coordinates to determine the coding unit at the predetermined position, so Various processes of comparing sizes of coding units determined according to predetermined sample point coordinates to determine a coding unit at a predetermined location may be used.

However, the position of the samples considered for determining the position of the coding unit should not be construed as being limited to the left upper end but may be interpreted as information on the position of any sample included in the coding unit can be used.

According to an embodiment, the image encoding device 100 may select a coding unit at a predetermined position from odd coding units determined by dividing the current coding unit in consideration of a form of the current coding unit. For example, if the current coding unit has a non-square shape whose width is greater than its height, the image decoding device 100 may determine the coding unit at a predetermined position according to the horizontal direction. In other words, the image decoding device 100 may determine one from coding units located at different positions in the horizontal direction and impose restrictions on the coding unit. If the current coding unit has a non-square shape whose height is greater than its width, the image decoding device 100 may determine a coding unit at a predetermined position according to a vertical direction. In other words, the image decoding device 100 may determine one from coding units located at different positions in the vertical direction and impose restrictions on the coding unit.

According to an embodiment, the image decoding device 100 may determine a coding unit at a predetermined position among the even coding units using information indicating respective positions of the even coding units. The image decoding device 100 may determine an even number of coding units by splitting (binary-split) a current coding unit, and may determine a coding unit at a predetermined position using information on positions of the even number of coding units. The specific process for this may correspond to the process of determining a coding unit at a predetermined position (eg, a central position) from an odd number of coding units described in detail with reference to FIG. 6 , so details are not repeated here.

According to an embodiment, when a current coding unit having a non-square shape is divided into a plurality of coding units, predetermined information about a coding unit at a predetermined position may be used in the division process to determine the coding unit at a predetermined position from among the plurality of coding units. coding unit. For example, the image decoding device 100 may use at least one of block shape information and split form mode information of samples stored in the central coding unit during the splitting process to select the current coding unit from a plurality of coding units that split the current coding unit. Determine the central coding unit.

Referring to FIG. 6 , the image decoding device 100 may divide the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c based on the division form mode information, and may determine a central coding unit from among the plurality of coding units 620a, 620b, and 620c. 620b. Furthermore, the image decoding device 100 may determine the central coding unit 620b in consideration of the position where the division form mode information is obtained. That is, the division form mode information may be obtained from the sample point 640 at the center of the current coding unit 600, and the division form mode information when the current coding unit 600 is divided into a plurality of coding units 620a, 620b, and 620c may be obtained based on the division form mode information. The coding unit 620b including the sample point 640 is determined as the central coding unit. However, information for determining a centrally located coding unit should not be construed as being limited to split form pattern information, but various information may be used in determining a centrally located coding unit.

According to an embodiment, predetermined information for identifying a coding unit at a predetermined position is obtainable from predetermined samples included in the coding unit to be determined. Referring to FIG. 6 , the image decoding device 100 may use division form mode information obtained from samples at predetermined positions within the current coding unit 600 (for example, samples located at the center of the current coding unit 600) to determine the number of points from which the current coding unit is divided. A coding unit at a predetermined position among the plurality of coding units 620 a , 620 b , and 620 c determined by the unit 600 (for example, a centrally located coding unit among the coding units divided into a plurality of coding units). That is to say, the image decoding device 100 may determine the sample point located at a predetermined position in consideration of the block shape of the current coding unit 600, and may determine the plurality of coding units 620a, 620b, and 620c by dividing the current coding unit 600. A coding unit 620b including a sample from which predetermined information (for example, division form mode information) can be obtained is determined and a predetermined restriction is imposed on the coding unit 620b. Referring to FIG. 6 , according to an embodiment, the image decoding device 100 may determine the sample point 640 located in the center of the current coding unit 600 as a sample point that can be used to obtain predetermined information, and may include the sample point in the decoding process Encoding unit 620b of 640 enforces predetermined constraints. However, the position of a sample point where predetermined information can be obtained should not be construed as being limited to the above-mentioned position, but may be construed as a sample point of any position included in the encoding unit 620b determined for setting restrictions.

According to an embodiment, the position of the sample point from which predetermined information can be obtained can be determined according to the shape of the current coding unit 600 . According to an embodiment, the block shape information may determine whether the shape of the current coding unit is square or non-square, and the position of a sample point from which predetermined information may be obtained may be determined according to the shape. For example, the image decoding device 100 may use at least one of the information about the width and the information about the height of the current coding unit to determine a sample point located on a boundary that divides at least one of the width and the height of the current coding unit in half. It is a sampling point from which predetermined information can be obtained from this sampling point. According to another example, when the block shape information on the current coding unit indicates a non-square shape, the image decoding device 100 may determine one of the samples adjacent to the boundary dividing the long side of the current coding unit in half as possible. Obtain samples of predetermined information.

According to an embodiment, when a current coding unit is divided into a plurality of coding units, the image decoding device 100 may determine a coding unit located at a predetermined position among the plurality of coding units using split form mode information. According to an embodiment, the image decoding device 100 may obtain division form mode information from samples at predetermined positions included in a coding unit, and may obtain division form mode information from samples at predetermined positions respectively included in a plurality of coding units by using A plurality of coding units generated by splitting the current coding unit are split using the information about the split form mode. In other words, the coding units may be recursively split using split form pattern information obtained from samples included in predetermined positions of each coding unit. The recursive division process of the coding unit has been described in detail with reference to FIG. 5 , so details are not repeated here.

According to an embodiment, the image decoding device 100 may determine at least one coding unit by dividing the current coding unit, and may determine an order of decoding the at least one coding unit according to a predetermined block (eg, the current coding unit).

FIG. 7 illustrates an order in which a plurality of coding units are processed when the image decoding device 100 divides a current coding unit to determine a plurality of coding units, according to an embodiment.

According to an embodiment, the image decoding device 100 may divide the first coding unit 700 in the vertical direction to determine the second coding units 710a and 710b according to the division mode information, and divide the first coding unit in the horizontal direction to determine the second coding units 730a and 730a. 730b, or divide the first coding unit 700 vertically and horizontally to determine the second coding units 750a, 750b, 750c, and 750d.

Referring to FIG. 7 , the image decoding device 100 may determine an order such that second coding units 710 a and 710 b determined by dividing the first coding unit 700 in a vertical direction are processed in a horizontal direction 710 c. The image decoding device 100 may place the processing order of the second coding units 730 a and 730 b determined by dividing the first coding unit 700 in a horizontal direction into a vertical direction 730 c. The image decoding device 100 may perform the processing according to a predetermined order (for example, raster scan order (raster scan order) or z scan order (z scan order) 750e, etc.) The second coding units 750a, 750b, 750c, 750d determined by dividing the first coding unit 700 in the vertical direction and the horizontal direction are determined.

According to an embodiment, the image decoding device 100 may recursively divide coding units. Referring to FIG. 7 , the image decoding device 100 may determine a plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 750d by dividing the first coding unit 700, and may recursively divide the determined plurality of coding units. 710a, 710b, 730a, 730b, 750a, 750b, 750c, 75Od. A method of dividing a plurality of coding units 710 a , 710 b , 730 a , 730 b , 750 a , 750 b , 750 c , 750 d may be a method corresponding to a method of dividing the first coding unit 700 . Accordingly, the plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d may each be independently divided into a plurality of coding units. Referring to FIG. 7 , the image decoding device 100 may divide the first coding unit 700 in a vertical direction to determine the second coding units 710a and 710b, and further, may determine whether to divide the second coding units 710a and 710b or not.

According to an embodiment, the image decoding device 100 may divide the second coding unit 710a on the left side into third coding units 720a and 720b in the horizontal direction, but may not divide the second coding unit 710b on the right side.

According to an embodiment, the processing order of the coding units may be determined according to the division process of the coding units. In other words, the processing order of the split coding units may be determined based on the processing order of the coding units before splitting. The image decoding device 100 may determine a processing order of the third coding units 720 a and 720 b determined by splitting the second coding unit 710 a on the left separately from the second coding unit 710 b on the right. Since the third coding units 720a and 720b are determined by dividing the second coding unit 710a on the left in a horizontal direction, the third coding units 720a and 720b may be processed in a vertical direction 720c. Also, the order in which the second coding unit 710a on the left and the second coding unit 710b on the right are processed corresponds to the horizontal direction 710c, and therefore, the third coding unit 720a included in the second coding unit 710a on the left and After 720b is processed in the vertical direction 720c, the right coding unit 710b may be processed. The above content is only used to illustrate the process of determining the processing order of each coding unit according to the coding unit before division, and it should not be interpreted as being limited to the above embodiment, but should be interpreted as the above content is applicable to coding determined by division in various forms Various methods in which units can be independently processed in a predetermined order.

FIG. 8 illustrates a process of determining that a current coding unit will be divided into an odd number of coding units when the image decoding device 100 cannot process coding units in a predetermined order, according to an embodiment.

According to an embodiment, the image decoding device 100 determines that the current coding unit is divided into an odd number of coding units based on information about the obtained block shape and split form mode. Referring to FIG. 8, a first coding unit 800 having a square shape may be divided into non-square second coding units 810a and 810b, and the second coding units 810a and 810b may be each independently divided into third coding units 820a, 820b, 820c, 820d and 820e. According to an embodiment, in the second coding unit, the image decoding device 100 may divide the left coding unit 810a in the horizontal direction to determine a plurality of third coding units 820a and 820b, and may divide the right coding unit 810b into an odd number The third encoding units 820c, 820d and 820e.

According to an embodiment, the image decoding device 100 may determine whether the third coding units 820a, 820b, 820c, 820d, and 820e can be processed in a predetermined order to determine whether there are coding units divided into an odd number. Referring to FIG. 8 , the image decoding device 100 may recursively divide the first coding unit 800 to determine third coding units 820a, 820b, 820c, 820d, and 820e. The image decoding device 100 may determine whether the first encoding unit 800, the second encoding units 810a and 810b, or the third encoding units 820a, 820b, 820c, 820d, and 820e are divided into an odd number of encodings in the dividing form based on the division form mode information. unit. For example, coding units located on the right side in the second coding units 810a and 810b may be divided into an odd number of third coding units 820c, 820d, and 820e. The processing order of the plurality of coding units included in the first coding unit 800 may be a predetermined order (for example, a z-scan order (z-scan order) 830, and the image decoding device 100 may determine that by placing the second coding unit on the right 810b is divided into an odd number to determine whether the third encoding units 820c, 820d, and 820e satisfy a condition that they can be processed in the predetermined order.

According to an embodiment, the image decoding device 100 may determine whether the third encoding units 820a, 820b, 820c, 820d, and 820e included in the first encoding unit 800 satisfy a condition that they can be processed in a predetermined order, the conditions are the same as whether they can At least one of the width and height of the second coding units 810a and 810b is divided in half according to the boundaries of the third coding units 820a, 820b, 820c, 820d, and 820e. For example, the third coding units 820a and 820b determined by dividing the height of the non-square-shaped left second coding unit 810a in half may satisfy the condition. The boundaries of the third coding units 820c, 820d, and 820e determined by dividing the second coding unit 810b on the right side into three coding units cannot divide the width or height of the second coding unit 810b on the right side in half, so it can be determined that Three encoding units 820c, 820d and 820e do not satisfy the condition. The image decoding device 100 may determine that the condition is not satisfied as a discontinuity of the scanning order (disconnection), and may determine that the second coding unit 810b on the right is divided into an odd number of coding units based on the determination result. According to an embodiment, when the coding unit is divided into an odd number of coding units, the image decoding device 100 may impose a predetermined restriction on the coding unit at a predetermined position among the divided coding units, since the detailed description with reference to various embodiments About these restricted content or predetermined location, so no more details.

FIG. 9 illustrates a process in which the image decoding device 100 divides the first coding unit 900 to determine at least one coding unit, according to an embodiment.

According to an embodiment, the image decoding device 100 may split the first coding unit 900 based on split form mode information obtained from a receiver (not shown). The square first coding unit 900 may be divided into four coding units having a square shape or divided into a plurality of non-square shaped coding units. For example, referring to FIG. 9 , when the first coding unit 900 is square and the division form mode information indicates division in non-square coding units, the image decoding device 100 may divide the first coding unit 900 into a plurality of non-square coding units. Specifically, when the division form mode information indicates that an odd number of coding units is determined by dividing the first coding unit 900 in a horizontal direction or a vertical direction, the image decoding device 100 may divide the square-shaped first coding unit 900 into an odd number of coding units. units, that is, the second coding units 910a, 910b, and 910c determined by dividing in the vertical direction or the second coding units 920a, 920b, and 920c determined by dividing in the horizontal direction.

According to an embodiment, the image decoding device 100 may determine whether the second encoding units 910a, 910b, 910c, 920a, 920b, and 920c included in the first encoding unit 900 satisfy a condition that can be processed in a predetermined order, the condition being the same as whether At least one of the width and the height of the first coding unit 900 may be divided in half according to boundaries of the second coding units 910a, 910b, 910c, 920a, 920b, and 920c. Referring to FIG. 9 , the boundaries of the second coding units 910a, 910b, and 910c determined by dividing the square-shaped first coding unit 900 in the vertical direction cannot divide the width of the first coding unit 900 in half, and thus the first coding unit 900 can be determined. Unit 900 does not meet the conditions that can be processed in a predetermined order. Also, the boundaries of the second coding units 920a, 920b, and 920c determined by dividing the square-shaped first coding unit 900 in the horizontal direction cannot divide the height of the first coding unit 900 in half, and thus it is possible to determine that the first coding unit 900 The conditions that can be processed in the predetermined order are not met. The image decoding device may determine that the condition is not satisfied as a discontinuity of the scanning sequence (disconnection), and based on the determination result, may determine that the first coding unit 900 is divided into an odd number of coding units. According to an embodiment, when the coding unit is divided into an odd number of coding units, the image decoding device 100 may impose a predetermined restriction on the coding unit at a predetermined position among the divided coding units, as described in detail with reference to various embodiments About these restricted content or predetermined location, so no more details.

According to an embodiment, the image decoding device 100 may divide the first coding unit to determine various forms of coding units.

Referring to FIG. 9 , the image decoding device 100 may divide a square-shaped first coding unit 900 and a non-square-shaped first coding unit 930 or 950 into various forms of coding units.

10 illustrates that when the image decoding device 100 divides the first coding unit 1000 to determine that the non-square-shaped second coding unit satisfies a predetermined condition, a form in which the second coding unit can be divided is limited, according to an embodiment.

According to an embodiment, the image decoding device 100 may determine to divide the square-shaped first coding unit 1000 into non-square-shaped second coding units 1010a, 1010b, based on division form mode information obtained from a receiver (not shown). 1020a, and 1020b). The second coding units 1010a, 1010b, 1020a, and 1020b may be independently divided. Thus, the image decoding device 100 may determine to divide the second coding units 1010a, 1010b, 1020a, and 1020b into multiple coding units or determine not to divide the second coding units 1010a, 1010b, 1020a, and 1020b based on the division form mode information of the respective second coding units 1010a, 1010b, 1020a, and 1020b. divided. According to an embodiment, the image decoding device 100 may determine the third coding units 1012 a and 1012 b by dividing the non-square-shaped left second coding unit 1010 a determined by dividing the first coding unit 1000 in the vertical direction in the horizontal direction. However, the image decoding device 100 may divide the left second coding unit 1010a in the horizontal direction and restrict the right coding unit 1010b from being divided in the same horizontal direction as that of the left second coding unit 1010a. When the third coding units 1014a and 1014b are determined by dividing the second coding unit 1010b on the right side in the same direction, the second coding unit 1010a on the left side and the second coding unit on the right side may each be independently divided in the horizontal direction. 1010b to determine the third coding unit 1012a, 1012b, 1014a and 1014b. However, this is the same result as the image decoding device 100 divides the first coding unit 1000 into four square-shaped second coding units 1030a, 1030b, 1030c, and 1030d based on the division form mode information, which is viewed from the perspective of image decoding May be inefficient.

According to an embodiment, the image decoding device 100 may determine the third coding unit 1022a, 1022b, 1024a by dividing the non-square-shaped second coding unit 1020a or 1020b determined by dividing the first coding unit 1000 in the horizontal direction in the vertical direction. and 1024b. However, when one of the second coding units (for example, the upper second coding unit 1020a) is divided in the vertical direction, the image decoding device 100 may restrict the other second coding unit (for example, the lower coding unit 1020b ) for the reason described above. It cannot be divided in the same vertical direction as the direction in which the upper second coding unit 1020a is divided.

FIG. 11 illustrates a process in which the image decoding device 100 divides a square-shaped coding unit when the division form pattern information cannot indicate division into four square-shaped coding units, according to an embodiment.

According to an embodiment, the image decoding device 100 may determine the second coding units 1110a, 1110b, 1120a, 1120b, etc. based on dividing the first coding unit 1100 in the division form mode information. The split form mode information may include information on various forms in which a coding unit may be divided, however, in some cases, information on various forms including four coding units for dividing a coding unit into a square may not be included. According to the split form mode information, the image decoding device 100 cannot split the square-shaped first coding unit 1100 into four square-shaped second coding units 1130a, 1130b, 1130c, and 1130d. Based on the split form mode information, the image decoding device 100 may determine the second coding units 1110 a , 1110 b , 1120 a , and 1120 b of a non-square shape, and so on.

According to an embodiment, the image decoding device 100 may each independently divide the non-square-shaped second coding units 1110a, 1110b, 1120a, and 1120b, and the like. The respective second coding units 1110a, 1110b, 1120a, and 1120b are divided in a predetermined order by a recursive method, which may be a division method corresponding to a method of dividing the first coding unit 1100 based on division form mode information.

For example, the image decoding device 100 may determine the square-shaped third coding units 1112a and 1112b by dividing the left second coding unit 1110a in the horizontal direction, and may determine the square shape by dividing the right second coding unit 1110b in the horizontal direction. The third encoding units 1114a and 1114b of . Further, the image decoding device 100 may determine square-shaped third coding units 1116 a , 1116 b , 1116 c , and 1116 d by dividing both the left second coding unit 1110 a and the right second coding unit 1110 b in a horizontal direction. In this case, the coding unit may be determined in the same form as that in which the first coding unit 1100 is divided into four square-shaped second coding units 1130a, 1130b, 1130c, and 1130d.

According to another example, the image decoding device 100 may determine the square-shaped third coding units 1122a and 1122b by dividing the upper second coding unit 1120a in the vertical direction, and may determine the square shape by dividing the lower second coding unit 1120b in the vertical direction. The third encoding units 1124a and 1124b of shape. Furthermore, the image decoding device 100 may determine square-shaped third coding units 1126 a , 1126 b , 1126 a , and 1126 b by dividing both the upper second coding unit 1120 a and the lower second coding unit 1120 b in a vertical direction. In this case, the coding unit may be determined in a shape similar to the second coding units 1130 a , 1130 b , 1130 c , and 1130 d that divide the first coding unit 1100 into four square shapes.

FIG. 12 illustrates that a processing order among a plurality of coding units may be changed according to a division process of coding units according to an embodiment.

According to an embodiment, the image decoding device 100 may divide the first coding unit 1200 based on the division form mode information. When the block shape is a square shape and the division form mode information indicates that the first coding unit 1200 is divided in at least one of a horizontal direction and a vertical direction, the image decoding device 100 may determine the second coding unit by dividing the first coding unit 1200 (eg, 1210a, 1210b, 1220a, and 1220b, etc.). Referring to FIG. 12 , non-square-shaped second coding units 1210a, 1210b, 1220a, and 1220b determined by dividing the first coding unit 1200 only in a horizontal direction or a vertical direction may be based on information about each of the second coding units 1210a, 1210b, 1220a, and The division form pattern information of 1220b is divided independently. For example, the image decoding device 100 may divide the second coding units 1210a and 1210b generated by dividing the first coding unit 1200 in the vertical direction into the horizontal direction to determine the third coding units 1216a, 1216b, 1216c, and 1216d, and may divide The third coding units 1226a, 1226b, 1226c, and 1226d are determined by dividing the second coding units 1220a and 1220b generated by the first coding unit 1200 in the horizontal direction, respectively. The division process of the second coding units 1210a, 1210b, 1220a, and 1220b has been described in detail in conjunction with FIG. 11 , so details are not repeated here.

According to an embodiment, the image decoding device 100 may process coding units in a predetermined order. Features related to the processing of coding units in a predetermined order have already been described in conjunction with FIG. 7 , so details are not repeated here. Referring to FIG. 12 , the image decoding device 100 may divide the square-shaped first coding unit 1200 to determine four square-shaped third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d. According to an embodiment, the image decoding device 100 may determine a processing order of the third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d according to the form in which the first coding unit 100 is divided.

According to an embodiment, the image decoding device 100 may determine the third coding units 1216a, 1216b, 1216c, and 1216d by dividing the second coding units 1210a and 1210b generated by dividing the vertical direction respectively in the horizontal direction, and may firstly use The third coding units 1216a and 1216c included in the second coding unit 1210a on the left are processed in the vertical direction, and then processed in the order 1217 of the third coding units 1216b and 1216d included in the second coding unit 1210b on the right in the vertical direction. The third encoding units 1216a, 1216b, 1216c and 1216d.

According to an embodiment, the image decoding device 100 may determine the third coding units 1226a, 1226b, 1226c, and 1226d by dividing the second coding units 1220a and 1220b generated by dividing them in the horizontal direction respectively in the vertical direction, and may first use The third encoding units 1226a and 1226b included in the upper second encoding unit 1220a are processed in the vertical direction, and then the third encoding units 1226c and 1226d included in the lower second encoding unit 1220b are processed in the order 1227 of the vertical direction. Coding units 1226a, 1226b, 1226c, and 1226d.

12, square-shaped third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d may be determined by dividing the second coding units 1210a, 1210b, 1220a, and 1220b, respectively. The second coding units 1210a and 1210b determined by dividing in the vertical direction and the second coding units 1220a and 1220b determined by dividing in the horizontal direction are divided in different forms from each other, however, if according to the third coding unit determined later Units, the first coding unit 1200 may be divided into coding units of the same shape. Based on this, by recursively dividing the coding unit in different processes based on the division form mode information, even if a plurality of coding units having the same shape as a result is determined, the image decoding device 100 can process such determination in a different order from each other. Multiple coding units of the same shape.

FIG. 13 illustrates a process of determining a depth of a coding unit as a shape and a size of the coding unit vary when the coding unit is recursively divided to determine a plurality of coding units, according to an embodiment.

According to an embodiment, the image decoding device 100 may determine a depth of a coding unit according to a predetermined reference. For example, the predetermined reference may be the length of the long side of the coding unit. When the length of the long side of the current coding unit is divided by 2n (n>0) times the length of the long side of the coding unit before splitting, the image decoding device 100 may determine that the depth of the current coding unit is deeper than that of the coding unit before splitting. The depth increases by n. Hereinafter, a coding unit whose depth is increased is represented as a coding unit having a lower bit depth.

Referring to FIG. 13 , based on block shape information indicating a square shape according to an embodiment (for example, the block shape information may indicate '0:SQUARE'), the image decoding device 100 may determine a lower bit depth by dividing the first coding unit 1300 having a square shape. The second encoding unit 1302, the third encoding unit 1304, and so on. If it is assumed that the square-shaped first coding unit 1300 has a size of 2N×2N, the second coding unit 1302 determined by dividing the width and height of the first coding unit 1300 by 1/2 times may have a size of N×N. Further, the third coding unit 1304 determined by dividing the width and height of the second coding unit 1302 into 1/2 size, respectively, may have a size of N/2×N/2. At this time, the width and height of the third coding unit 1304 are respectively equivalent to 1/4 times the width and height of the first coding unit 1300 . When the depth of the first coding unit 1300 is D, the depth of the second coding unit 1302 that is 1/2 times the width and height of the first coding unit 1300 may be D+1, and the width and height of the first coding unit 1300 The depth of the 1/4 times third coding unit 1304 may be D+2.

According to an embodiment, the image decoding device 100 may be based on block shape information indicating a non-square shape (for example, the block shape information may indicate '1: NS_VER', which indicates a non-square shape whose height is longer than width, or '2: NS_HOR', which Indicates that the width is longer than the height of the non-square) to divide the non-square shape of the first coding unit 1310 or 1320 to determine the second coding unit 1312 or 1322 of the lower bit depth, the third coding unit 1314 or 1324, and so on.

The image decoding device 100 may determine a second coding unit (eg, second coding units 1302 , 1312 , and 1322 , etc.) by dividing at least one of a width and a height of the first coding unit 1310 having an N×2N size. In other words, the image decoding device 100 may divide the first coding unit 1310 in the horizontal direction to determine the second coding unit 1302 having the size of N×N or the second coding unit 1322 having the size of N×N/2, or may divide the first coding unit 1310 in the horizontal direction and The second coding unit 1312 having a size of N/2×N is determined by dividing in the vertical direction.

According to an embodiment, the image decoding device 100 may determine the second coding unit (eg, 1302 , 1312 , and 1322 , etc.) by dividing at least one of a width and a height of the first coding unit 1320 having a size of 2N×N. That is to say, the image decoding device 100 may determine the second coding unit 1302 having an N×N size or the second coding unit 1312 having an N/2×N size by dividing the first coding unit 1320 in a vertical direction, or in The second coding unit 1322 of size N×N/2 is determined according to the horizontal direction and the vertical direction.

According to an embodiment, the image decoding device 100 may determine a third coding unit (eg, 1304 , 1314 , and 1324 , etc.) by dividing at least one of a width and a height of the second coding unit 1302 having an N×N size. In other words, the image decoding device 100 may determine the third coding unit 1302 having a size of N/2×N/2 and the third coding unit 1302 having a size of N/4×N/2 by dividing the second coding unit 1302 in a vertical direction and a horizontal direction. Three coding units 1314, or determine a third coding unit 1324 with a size of N/2×N/4.

According to an embodiment, the image decoding device 100 may determine a third coding unit (eg, 1304, 1314, and 1324, etc.) by dividing at least one of a width and a height of the second coding unit 1312 having an N/2×N size. That is, the image decoding device 100 may determine the third encoding unit 1304 having a size of N/2×N/2 or the third encoding unit having a size of N/2×N/4 by dividing the second encoding unit 1312 in the horizontal direction. The unit 1324, or the third coding unit 1314 having a size of N/4×N/2 may be determined by dividing the second coding unit 1312 in the vertical direction and the horizontal direction.

According to an embodiment, the image decoding device 100 may further determine the third coding unit (for example, 1304, 1314, and 1324, etc.) by dividing at least one of the width and height of the second coding unit 1322 having a size of N×N/2 . In other words, the image decoding device 100 may determine the third coding unit 1304 having the size of N/2×N/2 or the second coding unit 1304 of the size of N/4×N/2 by dividing the second coding unit 1322 in the vertical direction, Or the third coding unit 1324 having a size of N/2×N/4 may be determined by dividing the second coding unit 1322 in a vertical direction and a horizontal direction.

According to an embodiment, the image decoding device 100 may divide a coding unit having a square shape (for example, 1300, 1302, or 1304) in a horizontal direction or a vertical direction. For example, the first coding unit 1310 having the N×2N size is determined by dividing the first coding unit 1300 having the 2N×2N size in the vertical direction or the first coding unit 1300 having the 2N×N size is determined by dividing the first coding unit 1300 in the horizontal direction. A coding unit 1320 . According to an embodiment, when the depth is determined based on the longest side of the coding unit, the depth of the coding unit determined by dividing the first coding unit 1300 having a size of 2N×2N in a horizontal direction or a vertical direction may be the same as that of the first coding unit. The coding units 1300 have the same depth.

According to an embodiment, the width and height of the third coding unit 1314 or 1324 may be equivalent to 1/4 times that of the first coding unit 1310 or 1320 . When the depth of the first coding unit 1310 or 1320 is D, the depth of the second coding unit 1312 or 1322, which is 1/2 times the height and width of the first coding unit 1310 or 1320, may be D+1, as the first A depth of the third coding unit 1314 or 1324 that is 1/4 times the coding unit 1310 or 1320 may be D+2.

FIG. 14 illustrates a depth that may be determined according to a shape and size of a coding unit and a part index (PID) for distinguishing a coding unit, according to an embodiment.

According to an embodiment, the image decoding device 100 may determine second coding units having various shapes by dividing the first coding unit 1400 having a square shape. Referring to FIG. 14 , the image decoding device 100 may determine the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c by dividing the first coding unit 1400 in at least one of the vertical direction and the horizontal direction according to the division form mode information. and 1406d. That is, the image decoding device 100 may determine the second coding units 1402 a , 1402 b , 1404 a , 1404 b , 1406 a , 1406 b , 1406 c , 1406 d based on the division form mode information for the first coding unit 1400 .

According to an embodiment, the depths of the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, and 1406 determined based on the division form mode information for the square-shaped first coding unit 1400 may be based on the The length is determined. For example, the length of one side of the square-shaped first coding unit 1400 is the same as the length of the long side of the non-square-shaped second coding units 1402a, 1402b, 1404a, and 1404b, therefore, the first coding unit 1400 and the non-square-shaped Depths of the second coding units 1402a, 1402b, 1404a, and 1404b may be regarded as the same D. Conversely, when the image decoding device 100 divides the first coding unit 1400 into four square-shaped second coding units 1406a, 1406b, 1406c, and 1406d based on the division form mode information, the square-shaped second coding units 1406a, 1406b The length of one side of , 1406c, and 1406d is 1/2 times the length of one side of the first coding unit 1400, therefore, the depth of the second coding unit 1406a, 1406b, 1406c, and 1406d may be deeper than the depth D of the first coding unit 1400 One depth deeper, ie, D+1.

According to an embodiment, the image decoding device 100 may divide the first coding unit 1410 having a length greater than its width into a plurality of second coding units 1412a, 1412b, 1414a, 1414b, and 1414c in the horizontal direction according to the division mode information. According to an embodiment, the image decoding device 100 may divide the first coding unit 1420 having a width greater than its length into a plurality of second coding units 1422a, 1422b, 1424a, 1424b, and 1424c in the horizontal direction according to the division mode information.

According to an embodiment, the second coding units 1412a, 1412b, 1414a, 1414b, 1414c, 1422a, 1422b, 1424a, 1424b, and 1406 determined according to the division form mode information for the non-square-shaped first coding unit 1410 or 1420 The depth can be determined based on the length of the long side. For example, the length of one side of the square-shaped second coding unit 1412a, 1412b is 1/2 times the length of one side of the non-square-shaped first coding unit 1410 whose height is greater than the width, therefore, the square-shaped second coding unit The units 1412 a and 1412 b have a depth of one depth D+1 deeper than a depth D of the non-square-shaped first coding unit 1410 .

Further, the image decoding device 100 may divide the non-square-shaped first coding unit 1410 into an odd number of second coding units 1414a, 1414b, and 1414c based on the division form mode information. The odd number of second coding units 1414a, 1414b, and 1414c may include non-square-shaped second coding units 1414a and 1414c and a square-shaped second coding unit 1414b. In this case, the length of the long sides of the non-square-shaped second coding units 1414a and 1414c and the length of one side of the square-shaped second coding unit 1414b are equal to 1/1 of the length of one side of the first coding unit 1410. 2 times, therefore, the depths of the second coding units 1414 a , 1414 b , and 1414 c are depth D+1 which is one depth deeper than the depth D of the first coding unit 1410 . The image decoding device 100 may determine a depth of a coding unit related to the non-square-shaped first coding unit 1420 having a width greater than a height in a manner corresponding to the manner of determining a depth of a coding unit related to the first coding unit 1410 .

According to an embodiment, for determining the index PID for distinguishing the divided coding units, when the sizes of the odd divided coding units are different from each other, the image decoding device 100 may determine the index based on the size ratio between the coding units. . Referring to FIG. 14 , among divided odd-numbered coding units 1414a, 1414b, and 1414c, a centrally located coding unit 1414b may have the same width as other coding units 1414a and 1414c, however, its height may be equal to other coding units 1414a and 1414c. Twice the height of 1414c. In other words, in this case, the centrally located encoding unit 1414b may include two other encoding units 1414a and 1414c. Therefore, according to the scanning order, if the partial index PID of the coding unit 1414 located in the center is 1, the partial index of the coding unit 1414c located in the next order may be 3 which increases from 1 to 2. In other words, there can be discontinuities in index values. According to an embodiment, the image decoding device 100 may determine whether split odd-numbered coding units have the same size as each other based on whether discontinuity of an index for distinguishing split coding units exists.

According to an embodiment, the image decoding device 100 may determine whether to split using a specific split form based on a value of an index for distinguishing a plurality of coding units determined by splitting a current coding unit. Referring to FIG. 14 , the image decoding device 100 may determine an even number of coding units 1412 a and 1412 b or an odd number of coding units 1414 a , 1414 b , and 1414 c by dividing a rectangular-shaped first coding unit 1410 having a height greater than a width. The image decoding device 100 may distinguish a plurality of coding units using a PID of each coding unit. According to an embodiment, the PID may be obtained from samples at predetermined positions (for example, samples at the upper left end) in each coding unit.

According to an embodiment, the image decoding device 100 may determine a coding unit at a predetermined position among coding units determined by being split using an index for distinguishing coding units. According to an embodiment, when the division form information for the rectangular-shaped first coding unit 1410 whose height is larger than the width indicates that the first coding unit 1410 is divided into three coding units, the image decoding device 100 may divide the first coding unit 1410 into three coding units. There are three coding units 1414a, 1414b and 1414c. The image decoding device 100 may allocate respective indexes for the three coding units 1414a, 1414b, and 1414c. The image decoding device 100 may compare indexes regarding respective coding units to determine a central coding unit among divided odd-numbered coding units. The image decoding device 100 may determine a coding unit 1414b having an index corresponding to a central value of the index as a centrally located coding unit among coding units determined by splitting the first coding unit 1410 based on the index of the coding unit. According to an embodiment, for determining an index for distinguishing split coding units, when sizes of coding units are different from each other, the image decoding device 100 may determine the index based on a size ratio between coding units. Referring to FIG. 14 , a coding unit 1414b generated by dividing the first coding unit 1410 has the same width as other coding units 1414a and 1414c but may be twice as high as other coding units 1414a and 1414c of the same height. In this case, if the PID of the encoding unit 1414b located in the center is 1, the index of the encoding unit 1414 located in the next order is 3 which is incremented by 2. As in this case, when the increment changes when the index uniformly increases, the image decoding device 100 may determine to split by using a plurality of coding units including coding units having different sizes from other coding units. According to an embodiment, when the division form mode information indicates division by an odd number of coding units, the image decoding device 100 may use a coding unit having a predetermined position (for example, a central coding unit) among the odd number of coding units having The size of the coding unit divides the current coding unit in different sizes. In this case, the image decoding device 100 may determine a central coding unit having a different size using an index PID with respect to a coding unit. However, the above-mentioned index, the size or position of the coding unit at the predetermined position to be determined are predetermined for illustrating an embodiment, and the determination of the coding unit should not be interpreted as being limited, and it should be interpreted as that various indexes, coding units, etc. can be used. The location and size of the unit.

According to an embodiment, the image decoding device 100 may use a predetermined data unit to start recursive splitting of a coding unit.

FIG. 15 illustrates determining a plurality of coding units based on a plurality of predetermined coding units included in a picture, according to an embodiment.

According to an embodiment, a predetermined data unit may be defined as a data unit in which a coding unit is recursively divided starting using the division form pattern information. In other words, the predetermined data unit may be equivalent to a coding unit of the highest bit depth used in determining a plurality of coding units into which a current picture is divided. Hereinafter, for convenience of description, these predetermined data units are referred to as reference data units.

According to an embodiment, the reference data unit may indicate a predetermined size and shape. According to an embodiment, the reference CU may include M×N samples. Here, M and N may be the same as each other, or may be an integer expressed as a multiplier of 2. In other words, the reference data unit can exhibit a square or non-square shape, and can be divided into an integer number of coding units later.

According to an embodiment, the image decoding device 100 may divide the current picture into a plurality of reference data units. According to an embodiment, the image decoding device 100 may divide a plurality of reference data units for dividing a current picture using division form pattern information for each reference data unit. Such a division process of the reference data unit may correspond to a division process using a quad-tree structure.

According to an embodiment, the image decoding device 100 may determine in advance a minimum size that a reference data unit included in a current picture may have. Accordingly, the image decoding device 100 may determine reference data units having various sizes equal to or greater than the minimum size, and may determine at least one coding unit using the split form mode information based on the determined reference data units.

Referring to FIG. 15 , the image decoding device 100 may use either a square-shaped reference coding unit 1500 or a non-square-shaped reference coding unit 1502 . According to an embodiment, the shape and size of the reference coding unit may be determined by various data units (for example, sequence, picture, slice, slice) that may include at least one reference coding unit. segment) and the largest coding unit, etc.).

According to an embodiment, a receiver (not shown) of the image decoding device 100 may obtain at least one of information on the shape of the reference coding unit and information on the size of the reference coding unit from the bitstream according to the various data units. . The process of being divided by the current coding unit 300 of FIG. 3 describes in detail the process of determining at least one coding unit included in the square-shaped reference coding unit 1500, and the process of being divided by the current coding unit 400 or 450 of FIG. 4 is described in detail. The process describes in detail the process of at least one coding unit included in the non-square-shaped reference coding unit 1502 , so details are not repeated here.

According to an embodiment, the image decoding device 100 may use an index for identifying the size and shape of the reference coding unit to determine the size and shape of the reference coding unit from some data units predetermined based on predetermined conditions. In other words, for data units satisfying a predetermined condition (for example, a data unit whose size is smaller than or equal to a slice) among the various data units (for example, a sequence, a picture, a slice, a slice fragment, and a maximum coding unit, etc.) For each slice, slice segment, LCU, a receiver (not shown) can obtain only an index for identifying the size and shape of a reference CU from a bitstream. The image decoding device 100 may determine the size and shape of the reference data unit for each data unit satisfying the predetermined condition using the index. When the information on the shape of the reference coding unit and the information on the size of the reference coding unit are obtained and used from the bitstream according to relatively small data units, the usage efficiency of the bitstream may not be good, and therefore, only the index, instead of directly obtaining information about the shape of the reference CU and information about the size of the reference CU. In this case, at least one of the size and shape of the reference coding unit corresponding to the index indicating the size and shape of the reference coding unit may be predetermined. In other words, the image decoding device 100 may select at least one of the size and shape of a predetermined reference coding unit based on the index to determine at least one of the size and shape of the reference coding unit included in the data unit used as a reference for obtaining the index.

According to an embodiment, the image decoding device 100 may use at least one reference coding unit included in one maximum coding unit. In other words, the maximum coding unit of the divided image may include at least one reference coding unit, and the coding unit may be determined through a recursive division process of each reference coding unit. According to an embodiment, at least one of the width and the height of the LCU may be equivalent to an integer multiple of at least one of the width and the height of the reference CU. According to an embodiment, the size of the reference coding unit may be a size obtained by dividing the largest coding unit n times according to the quad-tree structure. In other words, the image decoding device 100 may determine the reference coding unit by dividing the maximum coding unit n times according to the quad-tree structure, and may divide the reference coding unit based on at least one of block shape information and information on the division form mode according to various embodiments. unit.

FIG. 16 illustrates processing blocks as a reference for determining a determination order of reference coding units included in a screen 1600 according to an embodiment.

According to an embodiment, the image decoding device 100 may determine at least one processing block for dividing a picture. A processing block is a data unit including at least one reference coding unit of a divided image, and the at least one reference coding unit included in the processing block can be determined in a specific order. In other words, the determination order of at least one reference coding unit determined in each processing block may correspond to one of the types in which the reference coding units may be determined, and the determination order of the reference coding units determined in each processing block may be determined according to each Processing blocks are different. The determination order of the reference coding unit determined in each processing block may be raster scan, Z-scan (Z-scan), N-scan (N-scan), upper-right diagonal scan (up-right diagonal scan) , horizontal scan, and vertical scan, however, the order that can be determined should not be construed as being limited to the scan order.

According to an embodiment, the image decoding device 100 may determine the size of at least one processing block included in the image by obtaining information on the size of the processing block. The image decoding device 100 may determine a size of at least one processing block included in an image by obtaining information on the processing block from a bitstream. The size of such a processing block may be a predetermined size of a data unit indicated by the information on the size of the processing block.

According to an embodiment, a receiver (not shown) of the image decoding device 100 may obtain information on the size of the processing block according to each predetermined data unit from the bit stream. For example, information about the size of a processing block can be obtained from the bitstream in terms of data units of images, sequences, pictures, slices, slice segments, and the like. In other words, the receiver (not shown) can respectively obtain information about the size of the processing block from the bitstream according to the plurality of data units, and the image decoding device 100 can use the obtained information about the size of the processing block to determine the Depending on the size of at least one processing block of the divided picture, the size of the processing block may be an integer multiple of the size of the reference coding unit.

According to an embodiment, the image decoding device 100 may determine the sizes of the processing blocks 1602 and 1612 included in the picture 1600 . For example, the image decoding device 100 may determine the size of the processing block based on information on the size of the processing block obtained from the bitstream. Referring to FIG. 16 , the image decoding device 100 may determine the horizontal size of the processing blocks 1602 and 1612 to be four times the horizontal size of the reference coding unit and determine the vertical size to be four times the vertical size of the reference coding unit according to an embodiment. The image decoding device 100 may determine an order in which at least one reference coding unit is determined within at least one processing block.

According to an embodiment, the image decoding device 100 may determine the respective processing blocks 1602 and 1612 included in the picture 1600 based on the sizes of the processing blocks, and may determine the size of at least one reference coding unit included in the processing blocks 1602 and 1612. Determine the order. According to an embodiment, determining the reference CU may include determining a size of the reference CU.

According to an embodiment, the image decoding device 100 may obtain information about a determined order of at least one reference coding unit included in at least one processing block from a bitstream, and may determine at least one based on the obtained information about the determined order. The order in which reference coding units are determined. The information on the determination order may be determined according to the order or direction in which the reference coding units within the processing block are determined. In other words, the order in which the reference CUs are determined can be determined independently in each processing block.

According to an embodiment, the image decoding device 100 may obtain information about a determined order of reference coding units from a bitstream according to each specific data unit. For example, a receiver (not shown) may obtain information about a determined order of reference coding units from a bitstream according to each data unit of an image, sequence, picture, slice, slice segment, processing block, and the like. The information on the determined order of the reference coding units indicates the determined order of the reference coding units within the processing block, and thus, the information on the determined order may be obtained according to each specific data unit including an integer number of processing blocks.

The image decoding device 100 may determine at least one reference coding unit based on an order determined according to an embodiment.

According to an embodiment, a receiver (not shown) may obtain, from a bitstream, information on a determined order of reference coding units as information on processing blocks 1602 and 1612, and the image decoding device 100 may determine the The order of at least one reference coding unit included in 1602 and 1612, and the at least one reference coding unit included in the picture 1600 may be determined based on the determined order of the coding units. Referring to FIG. 16 , the image decoding device 100 may determine determination orders 1604 and 1614 of at least one reference coding unit related to the respective processing blocks 1602 and 1612 . For example, when information on the determination order of reference coding units is obtained according to each processing block, the determination order of reference coding units related to the respective processing blocks 1602 and 1612 may be different according to each processing block. When the determination order 1604 of the reference coding units related to the processing block 1602 is a raster scan order, the reference coding units included in the processing block 1602 may be determined according to the raster scan order. On the contrary, when the determination order 1614 of the reference coding units related to other processing blocks 1612 is the reverse order of the raster scan order, the reference coding units included in the processing block 1612 are determined according to the reverse order of the raster scan order.

The image decoding device 100 may decode the determined at least one coding unit according to an embodiment. The image decoding device 100 may decode an image according to the reference coding unit determined through the above-mentioned embodiments. A method of decoding a reference coding unit may include various methods of decoding an image.

According to an embodiment, the image decoding device 100 may obtain and use block shape information indicating a shape of a current coding unit or split form mode information indicating a method of splitting the current coding unit from a bitstream. Partition form pattern information may be included in a bitstream related to various data units. For example, the image decoding device 100 can be used in sequence parameter set (sequence parameter set), picture parameter set (picture parameter set), video parameter set (video parameter set), slice header (slice header) and slice segment header (slice segment header) includes the division form pattern information. Furthermore, the image decoding device 100 may obtain a syntax element corresponding to the division form mode information from a bitstream according to the maximum coding unit, the reference coding unit, and the processing block and use the syntax element.

Hereinafter, a method for determining division rules according to an embodiment of the present disclosure will be described in detail.

The image decoding device 100 may determine a division rule of an image. The division rule may be predetermined between the image decoding device 100 and the image encoding device 150 . The image decoding device 100 may determine division rules of an image based on information obtained from a bitstream. The image decoding device 100 can be based on the sequence parameter set (sequence parameter set), picture parameter set (picture parameter set), video parameter set (video parameter set), slice header (slice header) and slice segment header (slice segment header) At least one of the obtained information is used to determine the division rule. The image decoding device 100 may differently determine splitting rules according to frames, slices, temporal layers, maximum coding units, or coding units.

The image decoding device 100 may determine a split rule based on a block shape of a coding unit. The block shape may include the size, shape, width-to-height ratio, and orientation of the coding unit. The image encoding device 150 and the image decoding device 100 may determine in advance a division rule based on a block shape of a coding unit. However, it is not limited to this. The image decoding device 100 may determine division rules based on information obtained from the bitstream received by the image decoding device 150 .

The shape of the coding unit may include square and non-square. When the width and height of the coding unit are the same as each other, the image decoding device 100 may determine the shape of the coding unit as a square. And, when the lengths of the width and the height of the coding unit are different from each other, the image decoding device 100 may determine the shape of the coding unit to be non-square.

The size of the coding unit may include various sizes of 4×4, 8×4, 4×8, 8×8, 16×4, 16×8, . . . , 256×256. The size of the coding unit can be classified according to the length of the long side, the length of the short side or the area of the coding unit. The image decoding device 100 may apply the same split rule to coding units classified into the same group. For example, the image decoding device 100 may classify coding units having the same length of long sides into the same size. And, the image decoding device 100 may apply the same split rule to coding units having the same long side length.

The ratio of the width to the height of the coding unit may include 1:2, 2:1, 1:4, 4:1, 1:8, 8:1, 1:16, or 16:1. And, the direction of the coding unit may include a horizontal direction and a vertical direction. The horizontal direction may indicate a case where the length of the width of the coding unit is greater than the length of the height. The vertical direction may indicate a case where the length of the width of the coding unit is smaller than the length of the height.

The image decoding device 100 may adaptively determine the split rule based on the size of the coding unit. The image decoding device 100 may variously determine allowable split form modes based on the size of a coding unit. For example, the image decoding device 100 may determine whether splitting may be allowed based on the size of the coding unit. The image decoding device 100 may determine a split direction according to a size of a coding unit. The image decoding device 100 may determine allowable split types according to the size of the coding unit.

Determining the division rule based on the size of the coding unit may be a division rule predetermined between the image encoding device 2300 and the image decoding device 100 . And, the image decoding device 100 may determine a division rule based on information obtained from a bitstream.

The image decoding device 100 may adaptively determine a split rule based on a location of a coding unit. The image decoding device 100 may adaptively determine a division rule based on a position that a coding unit occupies in an image.

And, the image decoding device 100 may determine a split rule to prevent coding units generated through split paths different from each other from having the same block shape. However, not limited thereto, coding units generated through different split approaches from each other may have the same block shape. Coding units generated through split approaches different from each other may have decoding processing orders different from each other. The decoding processing sequence has already been described in conjunction with FIG. 12 , so details are not repeated here.

Hereinafter, with reference to FIGS. 17 to 18 , the determination of the filter for the current sample based on at least one of the distance between the current sample in the current block and the reference sample and the size of the current block will be described in detail, and based on The determined filter performs an image encoding/decoding method and apparatus for intra prediction.

FIG. 17 is a diagram for explaining an intra prediction mode according to an embodiment.

Referring to FIG. 17 , intra prediction modes according to an embodiment may include a planar mode (mode 0 ) and a DC mode (mode 1 ). In addition, the intra prediction modes may include angle modes (modes 2 to 66) with prediction directions. Angle patterns may include diagonal patterns (pattern 2 or 66), horizontal patterns (pattern 18), and vertical patterns (pattern 50).

In the above, the intra prediction mode according to the embodiment has been described with reference to FIG. 17 , but is not limited thereto, and can have various shapes by adding a new intra prediction mode or subtracting an existing intra prediction mode. Intra-frame prediction mode, and those skilled in the art can understand that the mode number of each intra-frame prediction mode may vary from case to case.

18 is a diagram for explaining that according to an embodiment of the present disclosure, an image decoding device generates a current sample by using different filters based on at least one of the distance between the current sample and the reference sample and the size of the current block. Method for predicting sample points.

Referring to FIG. 18 , the image decoding device 100 may generate prediction sample values with respect to samples in a current block by using reference samples 1820 in order to perform intra prediction on the current block 1800 .

For example, the image decoding device 100 may determine the current block according to Eq. 1800 is the predicted sample point value px,y of the current sample point 1810 . Here, x and y may refer to the x coordinate and y coordinate of the current sample point based on the position of the upper left sample point of the current block.

[Formula 1]

p _{x, y} = f _{k, 0} * a _-1 + f _{k, 1} * a ₀ + f _{k, 2} * a ₁ + f _{k, 3} * a ₂

At this time, fk, i may refer to the i+1th (0<=i<=3) filtering of the k+1th filter in the filter set including M+1 (M is an integer) filter device coefficient. a0 may refer to the sample point value of the reference sample that intersects the extension line 1830 from the current sample point 1810, and a-1 may refer to the sample point value of the reference sample point that lies directly on the extension line 1830 from the current sample point 1810 To the left of the reference sample crossed by line 1830, and a1 may refer to the sample value of the reference sample that is directly to the right of the reference sample crossed by line 1830 extending from the current sample 1810, and a2 may be Refers to the sample point value of the reference sample point, which is located second to the right of the reference sample point that intersects the extension line 1830 from the current sample point 1810 .

In the above, the content of generating the predicted sample point value of the current sample point by using the reference sample point values a0, a-1, a1, a2 has been described according to formula 1, but it is not limited thereto, and those of ordinary skill in the art It can be understood that the predicted value of the current sample point can be generated based on a0 by using sample point values of various adjacent reference sample points. For example, the predicted sample point value of the current sample point can be generated by using a-2, a-1, a0 and a1. In addition, the predicted sample point value of the current sample point can be generated by using a0, a1, a2, and a3.

The image decoding device 100 may determine the filter to be used for the current sample 1810 among the plurality of filters fk (0<=k<=M) based on the distance between the current sample 1810 and the reference sample and the size of the current block 1800 device. For example, the image decoding device 100 may multiply the size of the current block by a predetermined ratio to predetermine the range of samples used by each of the plurality of filters fk (0<=k<=M), and will include the current sample The filter used within the range of samples of point 1810 is determined to be the filter for the current sample 1810 . For example, the number of filters included in the filter set may be four. In other words, the filter set may include filters f0, f1, f2 and f3.

When the distance between the current sample point 1810 and the reference sample point on the upper side of the current sample point 1810 is [0, size/4), or the distance between the current sample point 1810 and the reference sample point on the left side of the current sample point 1810 When the distance between is [0, size/4), the image decoding device 100 may determine f0 as the filter for the current sample point 1810. Here, size may be the size (height or width) of the current block 1800 . When the distance between the current sample point 1810 and the reference sample point on the upper side of the current sample point 1810 is [size/4, size/2) and the current sample point 1810 and the reference sample point on the left side of the current sample point 1810 The distance between is [size/4, size), or the distance between the current sample point 1810 and the reference sample point located on the left side of the current sample point 1810 is [size/4, size/2) and the current sample point 1810 When the distance from the reference sample point above the current sample point 1810 is [size/4, size), the image decoding device 100 may determine f1 as the filter for the current sample point 1810 . When the distance between the current sample point 1810 and the reference sample point on the upper side of the current sample point 1810 is [size/2, 3*size/4) and the current sample point 1810 and the reference sample point on the left side of the current sample point 1810 The distance between the sample points is [size/2, size), or the distance between the current sample point 1810 and the reference sample point located to the left of the current sample point 1810 is [size/2, 3*size/4) and When the distance between the current sample point 1810 and the reference sample point above the current sample point 1810 is [size/2, size), the image decoding device 100 may determine f2 as a filter for the current sample point 1810 .

When the distance between the current sample point 1810 and the reference sample point on the upper side of the current sample point 1810 is [3*size/4, size) and the current sample point 1810 and the reference sample point on the left side of the current sample point 1810 When the distance between is [3*size/4, size)), the image decoding device 100 may determine f3 as the filter for the current sample point 1810.

In other words, referring to FIG. 18 , when the current sample point 1810 is located in the first region 1850 , the image decoding device 100 may determine f0 as a filter for the current sample point 1810 . When the current sample 1810 is located in the second region 1860 , the image decoding device 100 may determine f1 as a filter for the current sample 1810 . When the current sample point 1810 is located in the third region 1870 , the image decoding device 100 may determine f2 as a filter for the current sample point 1810 . When the current sample point 1810 is located in the fourth region 1880 , the image decoding device 100 may determine f4 as a filter for the current sample point 1810 .

Here, among the smoothing strengths of the filters f0, f1, f2, and f3, the smoothing strength of the filter f0 for the sample point closest to the reference sample point may be the smallest, and the smoothing strength of the filter f0 for the sample point farthest from the reference sample point may be the smallest. The smoothing strength of the filter f0 of the point can be maximized.

In the above, it has been described with reference to FIG. 18 that the image decoding device 100 performs intra prediction on the current block by using four filters for the current block, but it is not limited thereto, and those of ordinary skill in the art can understand that Yes, the image decoding device 100 may perform intra prediction on a current block by using various numbers of filters. Here, the range of samples using each filter may be differently determined based on the number of filters. For example, referring to FIG. 18 , when the number of filters used for the current block 1800 is determined to be three, the image decoding device 100 may integrate the third area 1870 and the fourth area 1880 together, and when the current sample point 1810 is located at When in the third region 1870 or the fourth region 1880 , the image decoding device 100 may determine f3 as the filter for the current sample point 1810 .

In addition, the image decoding device 100 may predetermine the range of samples used for each of fk (0<=k<=M) based on the distance between the samples in the current block and the reference samples, and will be used for A filter within a range of samples including the current sample is determined as a filter for the current sample.

For example, when the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point is less than 4, the image decoding device 100 may determine f0 as the filter for the current sample point. When the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point is greater than or equal to 4 and less than 8, the image decoding device 100 may determine f1 as a filter for the current sample point. When the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point is greater than or equal to 8 and less than 16, the image decoding device 100 may determine f2 as the filter for the current sample point. When the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point is greater than or equal to 16 and less than 32, the image decoding device 100 may determine f3 as a filter for the current sample point. When the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point is greater than or equal to 32 and less than 64, the image decoding device 100 may determine f4 as the filter for the current sample point. When the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point is greater than 64, the image decoding device 100 may determine f5 as a filter for the current sample point. In this case, the image decoding device 100 may change the number of filters for the current block according to the size of the current block. It has been described that the image decoding apparatus 100 can predetermine each of the plurality of filters fk (0<=k<=M) to be used based on the minimum distance among the vertical and horizontal distances between the current sample point and the reference sample point range of sample points, but is not limited thereto. Those skilled in the art can understand that the image decoding device 100 can determine the reference sample that intersects with the extension line from the prediction direction of the current sample point based on the intra prediction mode of the current block. The distance between the points, and based on the distance between the reference sample points, predetermine the range of the sample points used by each of the plurality of filters fk (0<=k<=M).

In addition, it has been described that the image decoding device 100 may multiply the size of the current block by a predetermined ratio to predetermine the range of samples used by each of the plurality of filters fk (0<=k<=M), or based on the current The distance between the sample point in the block and the reference sample point predetermines the range of each used sample point of fk (0<=k<=M), but it is not limited thereto, and those of ordinary skill in the art can understand Yes, the image decoding device 100 can determine the number of samples used by each of the multiple filters based on at least one of the size of the current block and the distance between the samples in the current block and the reference samples. scope.

Also, the image decoding device 100 may determine the number of filters for the current block based on the size (height or width) of the current block, and determine a filter corresponding to the number of filters. For example, if the size of the current block is greater than or equal to a predetermined size, the image decoding device 100 may determine filters f0, f1, f2, . . . , and fM-1 as filters for the current block. When the size of the current block is smaller than the predetermined size, the image decoding device 100 may determine the number of filters for the current block to be a predetermined number K (K is an integer) smaller than M. In this case, the video decoding apparatus 100 may determine the predetermined number K filters according to predetermined combinations among various combinations of possible combinations of the filters f0, f1, f2, . . . , and fM-1. For example, the image decoding device 100 may determine filters f0, f1, f2, . . . , and fK-1 as filters for the current block. For example, when the number of filters for the current block is determined to be two, the image decoding device 100 may determine filters f0 and f1 as filters for the current block. Also, when the number of filters for the current block is determined to be two, the image decoding device 100 may determine filters f0 and fM-1 as filters for the current block.

For example, the image decoding device 100 may determine a 4-tap filter set including filters f0, f1, f2, and f3 for performing intra prediction on a current block as follows. For example, the image decoding device 100 may determine the coefficients of the filter f0 as {−2, 126, 4, 0}. (The filter coefficients refer to the filter coefficients applied to predetermined fractional pixel positions) The image decoding device 100 may determine the coefficients of the filter f1 as {12, 99, 18, -1}. The image decoding device 100 may determine the coefficients of the filter f2 as {21, 82, 23, 2}. The image decoding device 100 may determine the coefficients of the filter f3 as {31, 63, 33, 1}. Here, filter f0 may be the filter with the weakest smoothing strength among filters f0, f1, f2, and f3, and filter f3 may be the filter with the strongest smoothing strength among filters f0, f1, f2, and f3 . Meanwhile, the coefficient values of the filter are not limited to the coefficient values listed above, those skilled in the art can understand that the coefficient values of the filter can be slightly changed (eg +1 to 5, -1 to 5) and used.

Meanwhile, the image decoding device 100 may determine the number of reference samples for determining the predicted sample value of the current sample based on the distance between the current sample and the reference sample. The image decoding device 100 may perform filtering on a current sample by using reference samples corresponding to the number of reference samples.

For example, when the distance between the current sample and the reference sample is greater than or equal to a predetermined distance, the image decoding device 100 may generate a predicted sample value of the current sample by performing filtering on the current sample using M reference samples . When the distance between the current sample and the reference sample is less than the predetermined distance, the image decoding device 100 may generate a predicted sample value of the current sample by performing filtering on the current sample using less than M number of reference samples. For example, when the distance between the current sample and the reference sample is less than a predetermined distance, the image decoding device 100 may generate a predicted sample value of the current sample by performing filtering using one or two reference samples. When the distance between the current sample and the reference sample is greater than or equal to the predetermined distance, the image decoding device 100 may generate a predicted sample value of the current sample by performing filtering using four or more reference samples.

The image decoding device 100 may determine the number of reference samples used to perform filtering on a current sample by adjusting the number of taps of the filter. For example, when the distance between the current sample point and the reference sample point is greater than or equal to a predetermined distance, the image decoding device 100 may determine a filter having 4 taps or more as a filter for the current sample point. When the distance between the current sample point and the reference sample point is less than a predetermined distance, the image decoding device 100 may determine a 1-tap filter or a 2-tap filter as a filter for the current sample point. Here, the image decoding device 100 may not perform filtering instead of performing filtering by using a 1-tap filter.

In addition, the image decoding device 100 may determine the number of reference samples used to perform filtering on the current sample by fixing the number of taps of the filter and adjusting coefficient values of some filters.

For example, the image decoding device 100 may determine the number of taps of the filter as 4 taps, and when the distance between the current sample point and the reference sample point is less than a predetermined distance, determine the coefficient of the filter for the current sample point as {0, 128, 0, 0}. When the distance between the current sample point and the reference sample point is greater than or equal to the predetermined distance, the image decoding device 100 may determine the coefficients of the filter for the current sample point as {32, 63, 31, 1}.

The image decoding device 100 may determine a filter for the current sample from among filters for the current block based on the position of the current sample in the current block, the intra prediction mode, and the size of the current block.

For example, when the x-axis coordinate value of the current sample point is smaller than a predetermined value, or the y-axis coordinate value of the current sample point is smaller than a predetermined value, the image decoding device 100 may determine to use the first filter, otherwise it may determine to use the second filter device.

Here, the smoothing strength of the first filter is smaller than that of the second filter, and may have sharp characteristics. Here, the predetermined value may be 8, but is not limited thereto, and may be one of various values that are multiples of 4.

When the index value of the intra prediction mode of the current block is less than or equal to the index value of mode 34, the image decoding device 100 may determine whether the width of the current block is less than or equal to a first value and the height of the current block is less than or equal to a second value. Here, the first value may be smaller than the second value. For example, the first value may be 16 and the second value may be 32.

When the index value of the intra prediction mode of the current block is greater than the index value of mode 34, the image decoding device 100 may determine whether the width of the current block is less than or equal to a first value and the height of the current block is less than or equal to a second value. Here, the first value may be smaller than the second value. The first value may be 16 and the second value may be 32.

The image decoding device 100 may determine a filter for a current block based on the width and height of the current block. For example, when the width of the current block is less than or equal to the first value and the height of the current block is less than or equal to the second value, the image decoding device 100 may determine f0 and f1 as filters for the current block. When the width of the current block is greater than the first value, or the width of the current block is greater than the second value, the image decoding device 100 may determine f2 and f3 as filters for the current block.

FIG. 19 is used to illustrate that according to an embodiment of the present disclosure, the encoding (decoding) order between coding units is determined as forward or reverse based on the encoding order flag, and the reference line on the right or upper side according to the determined encoding (decoding) order Side reference lines can be used for intra-predicted graphs.

Referring to FIG. 19 , a maximum coding unit 1950 is divided into a plurality of coding units 1956 , 1958 , 1960 , 1962 , 1968 , 1970 , 1972 , 1974 , 1980 , 1982 , 1984 , and 1986 . The maximum coding unit 1950 corresponds to the highest node 1900 of the tree structure. In addition, a plurality of encoding units 1956, 1958, 1960, 1962, 1968, 1970, 1972, 1974, 1980, 1982, 1984, 1986 respectively correspond to a plurality of nodes 1906, 1908, 1910, 1912, 1918, 1920, 1922, 1924 , 1930, 1932, 1934 and 1936. Upper coding order marks 1902 , 1914 and 1926 indicating the coding order in the tree structure correspond to arrows 1952 , 1964 and 1976 , and upper coding order marks 1904 , 1916 and 1928 correspond to arrows 1954 , 1966 and 1978 .

The upper coding order flag indicates the coding order of two coding units located in the upper row among the four coding units of the same depth. When the coding sequence flag of the upper segment is 0, coding is performed in the forward direction. On the contrary, when the coding sequence flag of the upper segment is 1, coding is performed in the reverse direction.

Similarly, the lower coding order flag indicates the coding order of two coding units located in the lower row among the four coding units of the same depth. When the lower encoding sequence flag is 0, encoding is performed in the forward direction. On the contrary, when the coding sequence flag of the lower segment is 1, coding is performed in the reverse direction.

For example, the upper coding order flag 1914 is 0, so the coding order between the coding units 1968 and 1970 is determined along the forward direction from left to right. In addition, since the lower encoding order flag 1916 is 1, the encoding order between the encoding units 1972 and 1974 is determined in the reverse direction from the right to the left.

According to an embodiment, the upper encoding order flag and the lower encoding order flag may be set to have the same value. For example, when the upper coding sequence flag 1902 is determined to be 1, the lower coding sequence flag 1904 corresponding to the upper coding sequence flag 1902 may also be determined to be 1. Since the values of the upper encoding order flag and the lower encoding order flag are determined with 1 bit, the amount of information in the encoding order information is also reduced.

According to an embodiment, the upper coding order flag and the lower coding order flag of the current coding unit may be determined by referring to at least one of the upper coding order flag and the lower coding order flag applied to a coding unit having a depth smaller than the current coding unit. For example, upper coding order flag 1926 and lower coding order flag 1928 applied to coding units 1980 , 1982 , 1984 , and 1986 may be determined based on lower coding order flag 1916 applied to coding units 1972 and 1974 . Therefore, the upper encoding order flag 1926 and the lower encoding order flag 1928 may be determined to be the same value as the encoding order flag 1916 . The values of the upper coding order flag and the lower coding order flag are determined from the upper coding unit of the current coding unit, so the coding order information is not obtained from the bitstream. Therefore, the information amount of the encoding sequence information is also reduced.

Here, data including samples in the right adjacent coding unit 1958 decoded before the current coding unit 1986 and data 1980 and 1982 including samples in the upper side adjacent coding units may be used, so the image decoding device 100 can be determined by using data of samples included in the right adjacent encoding unit 1958 (right reference line) and data of samples included in upper adjacent encoding units 1980 and 1982 (upper reference line) Prediction is performed on embodiments according to the present disclosure.

In other words, it has been described with reference to FIGS. 17 to 18 that the filter used for the current sample is determined based on at least one of the size of the current block and the distance between the current sample and the reference sample, and based on the determined filter A method and apparatus for adaptively performing intra prediction by a device, and it has been described that on the premise that encoding and decoding are performed according to the encoding and decoding order of existing coding units, based on the upper or left angle with the current block Adjacent reference samples are used to perform intra-frame prediction, but it is not limited thereto, and those of ordinary skill in the art can understand that, as shown in Figure 19, when the encoding/decoding order between some adjacent coding units When the right CU or the reverse order of the left CU, intra prediction may be performed based on reference samples adjacent to the upper or right corner of the current block.

According to various embodiments of the present disclosure, the prediction accuracy can be improved by adaptively determining the filter currently used for the previous sample point based on the distance between the current sample point and the reference sample point, and a prediction of a natural pattern can be produced. piece.

In other words, prediction accuracy can be improved by using a filter with less smoothing strength and sharp characteristics for samples close to the reference sample. In addition, predictive blocks with natural patterns can be generated by applying filters with strong smoothing strength to samples far from the reference samples.

In addition, correction indicating a sudden prediction error can be performed by generating a prediction block with a natural pattern and high prediction accuracy, and thus transformation efficiency can be improved.

Various embodiments of the present disclosure have been described so far. It should be understood by those of ordinary skill in the art that the present disclosure can be realized in a modified shape without departing from the essential characteristics of the present disclosure. These embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the disclosure is defined not by the detailed description of the disclosure but by the appended claims, and all differences within the scope will be construed as being included in the present disclosure.

Embodiments of the present disclosure can be written as computer programs and implemented with general-purpose digital computers that execute the programs using a computer-readable recording medium. Examples of the computer-readable recording medium include magnetic storage media (eg, ROM, floppy disk, hard disk, etc.), optical recording media (eg, CD-ROM or DVD), and the like.

Claims (3)

1. an image decoding method, is characterized in that, comprises the steps: determining the samples of the left block as reference samples according to the intra prediction mode of the current block; When the x-coordinate value representing the position of the current sample point on the x-axis in the current block is less than or equal to a predetermined value, selecting a first filter among multiple filters; selecting a second filter among the plurality of filters when the x-coordinate value is greater than a predetermined value; applying one of the first filter and the second filter to the reference samples to generate prediction samples for the current sample, Wherein, the first filter includes first filter coefficients and second filter coefficients, The second filter includes third filter coefficients and fourth filter coefficients, the smoothing strength of the first filter is less than the smoothing strength of the second filter, The current block is a luma block or a chroma block. 2. An image coding method, characterized in that, comprising the steps of: determining the samples of the left block as reference samples according to the intra prediction mode of the current block; When the x-coordinate value representing the position of the current sample point on the x-axis in the current block is less than or equal to a predetermined value, select the first filter among the plurality of filters; selecting a second filter among the plurality of filters when the x-coordinate value is greater than a predetermined value; applying one of the first filter and the second filter to the reference samples to generate prediction samples for the current sample, Wherein, the first filter includes first filter coefficients and second filter coefficients, The second filter includes third filter coefficients and fourth filter coefficients, the smoothing strength of the first filter is less than the smoothing strength of the second filter, The current block is a luma block or a chroma block. 3. An image decoding device, characterized in that, comprising: Processor, configured as: determining the samples of the left block as reference samples according to the intra prediction mode of the current block; When the x-coordinate value representing the position of the current sample point on the x-axis in the current block is less than or equal to a predetermined value, selecting a first filter among multiple filters; selecting a second filter among the plurality of filters when the x-coordinate value is greater than a predetermined value; applying one of the first filter and the second filter to the reference samples to generate prediction samples for the current sample, Wherein, the first filter includes first filter coefficients and second filter coefficients, The second filter includes third filter coefficients and fourth filter coefficients, the smoothing strength of the first filter is less than the smoothing strength of the second filter, The current block is a luma block or a chroma block.

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