KR20140007097A - Method and apparatus for intra prediction using adaptive filtering - Google Patents

Abstract

Disclosed are a method and apparatus for performing intra prediction based on adaptive filtering. A method of performing intra prediction based on adaptive filtering is applied to a reference pixel based on a correlation between a current block and a neighboring block of the current block or a reference pixel used for intra prediction of the current block and a neighboring pixel of the reference pixel. And determining a method of applying a filter and a method of filtering, and filtering the reference pixel according to whether the determined filter is applied and a method of filtering. Therefore, based on the correlation between the directionality of the current block and the neighboring block of the current block or the intra prediction of the current block and the surrounding pixels of the reference pixel, adaptive filtering of the reference pixel is applied to the intra prediction. You can increase the accuracy.

Description

Intra prediction method and apparatus using adaptive filtering {METHOD AND APPARATUS FOR INTRA PREDICTION USING ADAPTIVE FILTERING}

The present invention relates to video encoding and decoding, and more particularly, to a method and apparatus for performing intra prediction based on adaptive filtering.

Recently, the emergence of smartphones and smart TVs has led to explosive use of video dating via wired and wireless communication networks. Video data has superior information transmission capability than plain text data, but has a very large capacity, which makes it difficult to transmit, reproduce and store data in a network channel having a limited bandwidth. In addition, since a large amount of moving picture information is appropriately processed according to the demand of an application, a system for processing a moving picture also requires a high specification.

In order to solve these problems, video encoding algorithms, which are techniques for compressing moving picture data into small information, have been actively studied. The video data has temporal, spatial, and statistical redundancies. Temporal redundancy means redundancy between successive frames, and pixel values of successive frames have a very high correlation. Spatial redundancy means redundancy existing in a frame, and a brightness value of one pixel has a high correlation with brightness values of neighboring pixels. Finally, statistical redundancy means redundancy between coded data, which is the redundancy due to the probability distribution of brightness values of pixels. In order to encode a moving image, a large amount of moving image data can be compressed into a smaller amount of data by eliminating the three redundancies.

Intra prediction is a method of compressing an image by eliminating spatial redundancy by using the degree of pixel correlation between blocks in one picture. The intra prediction is performed by using pixels adjacent to the current block restored by performing the previous encoding as reference pixels A predicted value of the current block is generated, and a difference value between the generated predicted value and the pixel value of the current block is compressed. In addition, HEVC (High Efficiency Video Coding), which is currently being standardized, adopts ADI (Arbitrary Direction Intra) prediction, Planar prediction, and Angular prediction as an intra prediction method.

In particular, in performing intra prediction, a filter may be applied to reference pixels before intra prediction is performed. That is, the current block is predicted by referring to a pixel value generated by applying a filter to adjacent pixels of a block neighboring the current block in consideration of the prediction mode and the size of the current block.

However, in some cases, encoding efficiency of a video may be improved when intra prediction is performed without filtering than performing filtering. Therefore, since the prediction is performed in a state in which the quantization error of neighboring pixels of the neighboring block used to predict the current block through intra prediction cannot be effectively reduced, there is a problem in that encoding efficiency is lowered.

Summary of the Invention An object of the present invention for solving the above problems is a method of performing intra prediction by applying adaptive filtering to a reference pixel based on a directionality according to an inter prediction intra prediction mode or a correlation between adjacent pixels of a neighboring block. To provide.

Another object of the present invention for solving the above problems is to perform intra prediction by applying adaptive filtering to a reference pixel based on the directionality according to the intra prediction mode between blocks or the correlation between adjacent pixels of a neighboring block. To provide a device.

In the intra prediction method according to an aspect of the present invention for achieving the above object, the correlation between the neighboring pixels of the reference pixel and the reference pixel used for intra prediction of the current block and the neighboring block of the current block or the current block Determining whether to apply a filter to the reference pixel and a filtering method based on the method, and filtering the reference pixel according to whether to apply the determined filter and the filtering method.

Here, when the current block and the neighboring blocks of the current block have the same directionality, it may be determined not to apply the filter to the reference pixel or to filter the reference pixel using the surrounding pixels of the reference pixel corresponding to the same directionality.

Here, the same directionality may include a case where the directionality of the current block and the directionality of neighboring blocks of the current block are within a preset angle range.

Here, when the direction of the current block and the direction of the neighboring block of the current block are directions perpendicular to each other, the reference pixel is applied by applying a filter to the reference pixel and using the peripheral pixels of the reference pixel corresponding to the direction of the neighboring block of the current block. May be determined to filter.

Here, the vertical direction may include a case within a range of a preset angle.

Here, when the difference value between the reference pixel and the surrounding pixels of the reference pixel is in the correlation greater than the preset threshold value, it may be determined not to apply the filter to the reference pixel.

Here, when the difference between the reference pixel and the peripheral pixel of the reference pixel has a correlation equal to or less than a preset threshold, the filter is applied to the reference pixel, or the difference value with the reference pixel among the peripheral pixels of the reference pixel is preset. It may be determined to filter the reference pixel using only the peripheral pixels of the reference pixel that are less than or equal to the threshold.

According to another aspect of the present invention, there is provided a decoding apparatus comprising: an entropy decoding unit for reconstructing a received bitstream to generate reconstruction information including quantized residual coefficients and intra prediction information; Determining whether or not to apply a filter to a reference pixel and a filtering method based on a correlation between a reference block used for intra prediction of the current block and a neighboring block of the current block or intra prediction of the current block And a reference pixel configuration unit for filtering and buffering the reference pixel according to the filtering determination unit and whether the determined filter is applied or not.

In case of using the intra prediction method using the filtering according to the present invention as described above, the adaptive filtering is applied to the reference pixel based on the directionality according to the intra prediction mode between blocks or the correlation between adjacent pixels of the neighboring block. You can increase the accuracy.

In addition, in intra prediction, coding efficiency may be improved by applying adaptive filtering to a reference pixel.

1 is a conceptual diagram of a current block and a reference block for explaining performing filtering according to an embodiment of the present invention.
2 is a conceptual diagram illustrating filtering based on directionality of a current block and a reference block according to an embodiment of the present invention.
3 is a conceptual diagram illustrating filtering based on directionality of a current block and a reference block according to another embodiment of the present invention.
4 is a block diagram illustrating an encoding apparatus for performing intra prediction according to an embodiment of the present invention.
5 is a block diagram illustrating a decoding apparatus for performing intra prediction according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

The Video Encoding Apparatus and the Video Decoding Apparatus to be described below may be implemented as a personal computer (PC), a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP) Such as a portable multimedia player (PSP), a PlayStation Portable (PSP), a wireless communication terminal, a smart phone, a TV application server and a service server. A communication device such as a communication modem for performing communication with a user terminal or a wired or wireless communication network, a memory for storing various programs and data for inter-screen or intra-screen prediction for coding or decoding a picture, coding or decoding, And a microprocessor for executing and operating and controlling It can mean a variety of devices.

In addition, the image encoded by the video encoding apparatus can be transmitted in real time or in non-real time through a wired or wireless communication network such as the Internet, a local area wireless communication network, a wireless LAN network, a WiBro network, a mobile communication network, A serial bus, and the like, and can be decoded and reconstructed into an image and reproduced by an image decoding apparatus.

The moving picture may be generally composed of a series of pictures, and each picture may be divided into a predetermined area such as a frame or a block.

In addition, HEVC (High Efficiency Video Coding), which is currently being standardized, defines concepts of a coding unit (CU), a prediction unit (PU), and a transform unit (TU). The hatching unit is similar to the existing macroblock, but allows the encoding to be performed while variably adjusting the size of the coding unit. The prediction unit is determined in a coding unit that is no longer split, and may be determined through a prediction type and a PU splitting process. The transform unit is a transform unit for transform and quantization, which may be larger than the size of the prediction unit, but not larger than the coding unit. Thus, in the present invention, a block can be understood as meaning equivalent to a unit.

In addition, a block or pixel referred to for encoding or decoding the current block or the current pixel is referred to as a reference block or a reference pixel. It is also to be understood that the term "picture" described below may be used in place of other terms having equivalent meanings such as image, frame, etc., If you are a child, you can understand.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a current block and a reference block for explaining performing filtering according to an embodiment of the present invention.

Referring to FIG. 1, an 8 × 8 current block and a neighboring block located above the current block are displayed. The current block to be encoded may refer to a pixel of a neighboring block located above the current block for intra prediction. However, when the difference between the pixels of the neighboring block to be referenced is large, the quantization error cannot be efficiently reduced.

Based on the directionality of the current block and the neighboring block of the current block, whether or not to apply the filter to the reference pixel may be determined.

In one embodiment of the present invention, the directionality of the current block and the neighboring block of the current block may have a vertical directionality. Here, if the intra prediction mode of the current block has a vertical direction, the current block may perform intra prediction using a neighboring block located above the current block as a reference block. That is, the reference block may have the same direction (vertical direction) as the current block, and there may be continuity between the reference block and the pixels of the current block.

In FIG. 1, the pixels in the rectangular box A have values of 35, 98, and 217, and when performing intra prediction using the pixel of 98 as a reference pixel, the pixels in the reference pixel 98 and its neighboring pixels 35 and 217 are represented. Low pass filter can be applied.

For example, if a 3-tap filter with coefficients 1/4, 1/2, 1/4 is applied to square box A, then (1/4) × 35 + (1/2) × 98 + (1/4) × A value of 217 = 112 may be obtained, and intra prediction of the vertical direction may be performed using the 112 value as the reference pixel. In this case, because the difference between the reference pixel 98 and the surrounding pixels 35 and 217 is large, the accuracy of prediction may be lowered. Therefore, it is effective to perform intra prediction using the reference pixel 98 without a filter applied. to be.

In addition, filtering the reference pixel using pixels around the reference pixel corresponding to the directionality of the reference block may increase the accuracy of prediction. For example, a filter may be applied to the reference pixel 98 and the upper pixel 94 of the reference pixel. That is, filtering may be performed to reflect the continuity of the pixels constituting the reference block.

Therefore, when the current block and the neighboring blocks of the current block have the same directionality, filtering the reference pixel by not applying the filter to the reference pixel or using the neighboring pixels of the reference pixel corresponding to the same directionality may increase the accuracy of prediction. have.

In addition, the current block may have a vertical direction and neighboring blocks of the current block may have a horizontal direction. Here, if the intra prediction mode of the current block has a vertical direction, the current block may perform intra prediction using a neighboring block located above the current block as a reference block. That is, the direction of the current block and the direction of the reference block may be perpendicular to each other.

In FIG. 1, the pixels in the rectangular box B have values of 188, 192, and 189, and when performing intra prediction with the pixel of 192 as the reference pixel, the pixels in the reference pixel 192 and the neighboring pixels 188 and 189 are performed. Low pass filter can be applied.

For example, if a 3-tap filter with coefficients 1/4, 1/2, 1/4 is applied to a square box B, then (1/4) × 188 + (1/2) × 192 + (1/4) × A value of 189 ≒ 190 is obtained and vertical prediction may be performed using the 190 value as a reference pixel. In this case, a filter may be applied to the reference pixel 192 to increase the accuracy of prediction, and a low pass filter (eg, a 5-tap filter) having more coefficients may be used.

Therefore, when the direction of the current block and the direction of the neighboring block of the current block are directions perpendicular to each other, the filter is applied to the reference pixel and the reference pixel is selected using the peripheral pixels of the reference pixel corresponding to the direction of the neighboring block of the current block. You can filter.

2 is a conceptual diagram illustrating filtering based on directionality of a current block and a reference block according to an embodiment of the present invention.

Referring to FIGS. 2A and 2C, when the current block and neighboring blocks of the current block have the same direction (vertical direction or right diagonal direction), the filter is not applied to the reference pixel or the peripheral pixel of the reference pixel corresponding to the same direction is used. To filter the reference pixel.

As described above with reference to the rectangular box A in FIG. 1, when the current block and the reference block have the same directionality, since there is continuity between the pixels of the current block and the reference block, quantization is performed through filtering on the reference pixel in intra prediction. The effect of reducing errors can be minimal. In addition, filtering the reference pixel by using the peripheral pixels of the reference pixel corresponding to the same direction indicating the continuity between the pixels may increase the accuracy of intra prediction.

In addition, when the direction of the current block is diagonal down right as illustrated in FIG. 2C, intra prediction may be performed on the left, upper left, and upper blocks of the current block as reference blocks. That is, even in this case, the reference pixel may be filtered by not applying the filter to the reference pixel or by using the peripheral pixels of the reference pixel corresponding to the same directionality (diagonal down right).

Accordingly, the above-described embodiment of the present invention may be applied to the case where the intra prediction direction is diagonal down right, and may also be applied to the intra prediction mode having another direction.

Referring to FIG. 2B, when the direction of the current block and the direction of the neighboring block of the current block are perpendicular to each other, the filter is applied to the reference pixel and the neighboring pixels of the reference pixel corresponding to the direction of the neighboring block of the current block are used. To filter the reference pixel.

As described above with reference to the rectangular box B in FIG. 1, when the current block has a horizontal orientation and the reference block of the current block has a vertical orientation, it is perpendicular to the reference block. Since the pixels placed at have similar values (that is, the pixels used for prediction of the current block have similar values), the reference pixels are filtered using the neighboring pixels of the reference pixel corresponding to the directionality of the neighboring blocks of the current block. In this way, the efficiency of intra prediction can be improved by reducing the quantization error efficiently.

In addition, since the pixels placed in the vertical direction in the reference block have high correlation, applying a low pass filter (for example, a 5-tap filter) that uses many pixels can reduce the quantization error more efficiently. Alternatively, the quantization error may be reduced by applying a low pass filter to the reference pixel and its surrounding pixels several times.

The above-described embodiments of the present invention describe some examples of adaptively applying filtering according to the relationship between a current block and a block neighboring the current block in intra prediction, and adaptively filtering based on the directionality between blocks. It may include other examples that can be applied.

3 is a conceptual diagram illustrating filtering based on directionality of a current block and a reference block according to another embodiment of the present invention.

Referring to FIGS. 3A and 3C, the filter is not applied to the reference pixel or the same directionality is applied not only when the current block and the neighboring blocks of the current block have the same directivity (vertical direction or diagonal rightward downward), but also have almost the same directivity. It is possible to determine to filter the reference pixel using the surrounding pixels of the reference pixel corresponding to approximately the same directionality. That is, the same directionality may include a case where the directionality of the current block and the directionality of the neighboring block (reference block) of the current block are within a range of a predetermined angle θ.

Referring to FIG. 3B, the filter is applied to the reference pixel and the directionality of the neighboring block of the current block is applied not only when the directionality of the current block and the directionality of the neighboring block of the current block are perpendicular to each other but also the directions that are almost perpendicular to each other. It may be determined to filter the reference pixel using the neighboring pixels of the reference pixel corresponding to. That is, the vertical direction may include the case in the range of the preset angle θ.

Therefore, the above-described embodiment of the present invention may be applied to the case where the intra prediction direction is diagonal down right, and may also be applied to the intra prediction mode having another direction. In addition, the present invention may be applied to Arbitrary Direction Intra (ADI) prediction, Planar prediction, and Angular prediction, which is an intra prediction method according to HEVC, which is currently being standardized.

According to another embodiment of the present invention, whether a filter is applied to a reference pixel and a filtering method may be determined based on a correlation between a reference pixel used for intra prediction of a current block and a neighboring pixel of the reference pixel.

Referring to FIG. 1, pixels located in a rectangular box A of a neighboring block may have values of 35, 98, and 217, and pixels located in a rectangular box B may have 188, 192, and 189.

Intra prediction may be performed using the pixels positioned at the centers of the rectangular boxes A and B as reference pixels 98 or 192.

At this time, if the difference value between the reference pixel and the peripheral pixels of the reference pixel is larger than the preset threshold value, the difference value between the reference pixel and the peripheral pixels of the reference pixel is preset threshold value without applying the filter to the reference pixel. In the following cases, it may be determined to apply the filter to the reference pixel.

First, the explanation is based on square box A. If a 3-tap filter with coefficients of 1/4, 1/2, 1/4 is applied to square box A, (1/4) × 35 + (1/2) × A value of 98 + (1/4) x 217 = 112 is obtained, and intra prediction in the vertical direction may be performed using the value 112 as the reference pixel. In this case, because the difference between the reference pixel 98 and the surrounding pixels 35 and 217 is large, the accuracy of prediction may be lowered. Therefore, it is effective to perform intra prediction using the reference pixel 98 without a filter applied. to be.

For example, if the preset threshold is 10, the difference between the reference pixel 98 located in the center of the rectangular box A and the adjacent peripheral pixels 35 and 217 is greater than 10, so that the filter is referred to as a reference pixel ( Intra prediction can be performed without applying the method.

Next, referring to the rectangular box B, if a 3-tap filter having a coefficient of 1/4, 1/2, 1/4 is applied to the rectangular box B, it is (1/4) × 188 + (1/2). A value of 192 × (1/4) × 189 × 190 is obtained, and intra prediction in the vertical direction may be performed using the 190 value as the reference pixel. In this case, a filter may be applied to the reference pixel 192 to increase the accuracy of prediction, and a low pass filter (eg, a 5-tap filter) having more coefficients may be used.

For example, if the preset threshold is 10, the difference between the reference pixel 192 positioned in the center of the rectangular box B and the adjacent peripheral pixels 188 and 189 is 10 or less, so that the filter is referred to as a reference pixel ( 98) to perform intra prediction.

In addition, when the difference value between any one of the reference pixel located in the center and the adjacent peripheral pixels is equal to or less than a preset threshold, the filter may be set to be applied or not applied to the reference pixel.

In addition, the reference pixel may be filtered using only the peripheral pixels of the reference pixel having a difference value with respect to the reference pixel or less among the peripheral pixels of the reference pixel.

For example, in the case of the pixels 217, 188, and 192, the difference between the reference pixel 188 located at the center and the reference pixel 188 and the pixel having a value of 217 on the left of the adjacent peripheral pixels is set in advance. The pixel having a value of 188 and the reference pixel 192 are larger than the threshold 10, but the difference between the pixel having the value of 192 on the right side and the reference pixel 188 is less than or equal to the preset threshold 10. Intra prediction may be performed using a pixel generated by applying a filter (eg, a 2-tap filter having coefficients of 3/4 and 1/4).

In addition, referring to FIG. 2D, if the direction of the current block is diagonal down right, intra prediction may be performed on the left, upper left, and upper blocks of the current block as the reference block. In such a case, whether or not to apply a filter to a reference pixel and a method of filtering may be determined based on a correlation between the directionality of the current block and the reference block or the reference pixel used for intra prediction of the current block and the surrounding pixels of the reference pixel. have. For example, when the upper block or the left block is a reference block, whether to apply a filter or a filtering method can be determined based on the directionality of the current block and the reference block. Based on the correlation between the neighboring pixels of the pixel, whether or not to apply the filter may be determined.

The above-described embodiments of the present invention describe some examples of adaptively applying filtering according to the correlation between the reference pixel and the neighboring pixels of the reference pixel in intra prediction, and based on the correlation between the pixels Other examples may include adaptive filtering.

4 is a block diagram illustrating an encoding apparatus for performing intra prediction according to an embodiment of the present invention.

Referring to FIG. 4, the encoding apparatus 100 according to an exemplary embodiment of the present invention includes a subtractor 110, a transform unit 120, an inverse transform unit 121, a quantization unit 130, an inverse quantization unit 131, and entropy. The encoder 140, the adder 150, the filtering determiner 160, the reference pixel configuration unit 170, and the intra predictor 180 are included.

The subtractor 110 generates a residual image between the current image and the predicted image by subtracting the predicted image generated by the predictor from the target image to be encoded (the current image), which is the provided input image.

The converter 120 converts the residual image generated by the subtractor 110 from the spatial domain to the frequency domain. Here, the transform unit 120 may convert the residual image into the frequency domain by using a technique of transforming an image signal of a spatial axis into a frequency axis, such as a Hadamard transform, a discrete cosine transform, or the like.

The quantization unit 130 quantizes the transformed data (frequency coefficients) supplied from the transform unit 120. [ That is, the quantization unit 130 calculates a quantization result value by approximating the frequency coefficients, which are data converted by the transform unit 120, by dividing the frequency coefficients by a quantization step size.

The entropy encoding unit 140 generates a bit stream by entropy encoding the quantization result value calculated by the quantization unit 130. In addition, the entropy encoder 140 may entropy-encode the quantization result value calculated by the quantizer 130 using CAVLC (Context-Adaptive Variable Length Coding) or CABAC (Context-Adaptive Binary Arithmetic Coding). In addition to the quantization result, entropy encoding may be performed on index information of a reference frame, information of a motion vector, inter prediction information, and the like, which are information (decoding information) necessary for decoding an image.

The inverse quantization unit 131 dequantizes the quantization result value calculated by the quantization unit 130. [ That is, the inverse quantization unit 131 restores the value (frequency coefficient) of the frequency domain from the quantization result value.

The inverse transformer 121 restores the residual image by converting a value (frequency coefficient) of the frequency domain provided by the inverse quantizer 131 from the frequency domain to the spatial domain, and the adder 150 is a predictor (intra predictor). The reconstructed image of the input image may be generated by adding the residual image reconstructed by the inverse change unit 121 to the predicted image generated by the reverse image.

The filtering determiner 160 may determine whether to apply a filter to a reference pixel, which is a pixel adjacent to the current block reconstructed by performing encoding, and a filtering method. That is, as described above, the filtering determination unit 160 may determine a correlation between the current pixel and the neighboring pixels of the current block or the neighboring pixels of the reference pixel used for intra prediction of the current block and the neighboring blocks (reference blocks) of the current block. Based on the determination, whether a filter is applied to a reference pixel and a filtering method may be determined.

The reference pixel configuration unit 170 may apply and buffer the filter to the reference pixel according to whether the filter determined by the filtering determination unit 160 is applied and the filtering method.

The intra predictor 180 performs intra prediction using the reference pixel buffered in the reference pixel configuration unit 170. Intra prediction may generate a prediction block by predicting pixels of a current block by using pixels of a block that is previously encoded, decoded, and reconstructed in a current picture that performs current encoding.

Accordingly, the encoding apparatus 100 according to the embodiment of the present invention may perform intra prediction using the adaptive filtering as described above.

5 is a block diagram illustrating a decoding apparatus for performing intra prediction according to an embodiment of the present invention.

Referring to FIG. 5, the decoding apparatus 200 according to the embodiment of the present invention includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an adder 240, and a filtering determiner 250. , The reference pixel configuration unit 260 and the intra prediction unit 270, and play the same role as the configuration of the encoding apparatus 100 of FIG. 4.

The entropy decoder 210 entropy decodes the bitstream generated from the encoding apparatus 100 shown in FIG. 4, and the inverse quantizer 220 inversely quantizes the data received from the entropy decoder 210 in the frequency domain. Restore to the value of (frequency coefficient). In addition, the inverse transformer 230 inversely converts a value (frequency coefficient) in the frequency domain from the frequency domain to the spatial domain. The adder 240 generates a reconstructed image of the current image by adding the residual image (residual value) reconstructed by the inverse transformer 230 to the predicted image generated by the intra predictor 270.

In particular, the decoding apparatus 200 according to an embodiment of the present invention refers to the entropy decoding unit 210 and reconstruction information for reconstructing the received bitstream to generate reconstruction information including quantized residual coefficients and intra prediction information. Determining whether or not to apply a filter to a reference pixel and a filtering method based on a correlation between a reference block used for intra prediction of the current block and a neighboring block of the current block or intra prediction of the current block The filter determining unit 250 and the reference pixel configuration unit 260 for filtering and buffering the reference pixel according to whether the determined filter is applied and the filtering method are included.

Accordingly, the decoding apparatus 200 according to the embodiment of the present invention may perform intra prediction using the adaptive filtering as described above.

The intra prediction method according to the present invention described above can increase the accuracy of intra prediction by applying adaptive filtering to the reference pixel based on the inter-block intra prediction mode or the correlation between adjacent pixels of neighboring blocks. Through this, coding efficiency can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

100: encoding apparatus 110: subtractor
120: converter 121, 230: inverse converter
130: quantization unit 131, 220: inverse quantization unit
140: entropy encoding unit 150, 240: adder
160, 250: filtering determining unit 170, 260: reference pixel configuration unit
180, 270: intra prediction unit 200: decoding apparatus
210: entropy decoding unit

Claims (14)

In the video encoding / decoding method,
Whether or not the filter is applied to the reference pixel based on the correlation between the current block and the directionality of the neighboring block of the current block or the reference pixel used for intra prediction of the current block and the peripheral pixels of the reference pixel Determining a method; And
And filtering the reference pixel according to whether the determined filter is applied and the filtering method. The method according to claim 1,
When the current block and the neighboring block of the current block have the same direction, determining not to apply the filter to the reference pixel or to filter the reference pixel by using the peripheral pixels of the reference pixel corresponding to the same direction. Intra prediction method using adaptive filtering, characterized in that. The method according to claim 2,
Wherein the same directionality includes a case where the directionality of the current block and the directionality of neighboring blocks of the current block are within a preset angle range. The method according to claim 1,
When the direction of the current block and the direction of the neighboring block of the current block are directions perpendicular to each other, the filter is applied to the reference pixel and the neighboring pixels of the reference pixel corresponding to the direction of the neighboring block of the current block are used. And determine to filter the reference pixel. The method of claim 4,
And the vertical direction is within a range of a predetermined angle. The method according to claim 1,
Intra-adaptation using adaptive filtering, wherein the filter is determined not to be applied to the reference pixel when a difference value between the reference pixel and a peripheral pixel of the reference pixel is greater than a predetermined threshold value. Forecast method. The method according to claim 1,
Apply the filter to the reference pixel when the correlation value between the reference pixel and the neighboring pixel of the reference pixel is equal to or less than a preset threshold;
Intra prediction using adaptive filtering, characterized in that it is determined to filter the reference pixel using only the peripheral pixel of the reference pixel whose difference value with the reference pixel among the peripheral pixels of the reference pixel is equal to or less than the preset threshold value. Way. In the video decoding apparatus,
An entropy decoding unit reconstructing the received bitstream to generate reconstruction information including quantized residual coefficients and intra prediction information;
A filter for the reference pixel based on a directionality of a current block and a neighboring block of the current block with reference to the reconstruction information, or a correlation between a reference pixel used for intra prediction of the current block and a peripheral pixel of the reference pixel; A filtering determining unit to determine whether to apply the filtering method and the filtering method; And
And a reference pixel configuration unit configured to filter and buffer the reference pixel according to whether the determined filter is applied and the filtering method. The method of claim 8, wherein the filtering determination unit,
When the current block and the neighboring block of the current block have the same direction, determining not to apply the filter to the reference pixel or to filter the reference pixel by using the peripheral pixels of the reference pixel corresponding to the same direction. Decoding apparatus for performing intra prediction using the adaptive filtering, characterized in that. The method of claim 9,
And wherein the same directionality includes a case where the directionality of the current block and the directionality of neighboring blocks of the current block are within a preset angle range. The method of claim 8, wherein the filtering determination unit,
When the direction of the current block and the direction of the neighboring block of the current block are directions perpendicular to each other, the filter is applied to the reference pixel and the neighboring pixels of the reference pixel corresponding to the direction of the neighboring block of the current block are used. And intra-prediction using adaptive filtering, characterized in that it is determined to filter the reference pixel. The method of claim 11,
And the vertical direction includes a case in which the vertical direction is within a range of a predetermined angle. The method of claim 8, wherein the filtering determination unit,
Intra-adaptation using adaptive filtering, wherein the filter is determined not to be applied to the reference pixel when a difference value between the reference pixel and a peripheral pixel of the reference pixel is greater than a predetermined threshold value. Decoding apparatus for performing prediction. The method of claim 8, wherein the filtering determination unit,
Apply the filter to the reference pixel when the difference value between the reference pixel and the peripheral pixel of the reference pixel is greater than or equal to a predetermined threshold value;
Intra prediction using adaptive filtering is determined to apply the filter using only the neighboring pixels of the reference pixel whose difference value with the reference pixel is less than or equal to the preset threshold among the surrounding pixels of the reference pixel. Decryption apparatus to perform.

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