JP2014168107A - Video encoding device, video decoding device, video encoding method and video decoding method - Google Patents

Abstract

To suppress the occurrence of aliasing and improve encoding efficiency.
An intra-prediction unit 4 of a moving image coding apparatus applies a plurality of pixels adjacent to each other in a horizontal direction and a vertical direction among pixels constituting an encoded block divided by a block dividing unit 2. The luminance component is smoothed, a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component is calculated, and a predicted image for the color difference component is generated using the correlation parameter and the smoothed luminance component. Configure.
[Selection] Figure 1

Description

  The present invention relates to a moving image encoding apparatus and moving image encoding method for encoding a moving image with high efficiency, a moving image decoding apparatus and a moving image decoding method for decoding a moving image encoded with high efficiency, and It is about.

For example, in the moving image encoding apparatus described in Non-Patent Document 1 below, as a prediction unit that performs intra-frame prediction of a color difference signal, a correlation between the luminance signal and the color difference signal is used to generate a reduced luminance signal. An Intra_LM mode that predicts a color difference signal by performing a numerical operation is employed.
FIG. 18 is a configuration diagram illustrating a luminance correlation use color difference signal prediction unit that performs prediction processing in the Intra_LM mode.
The luminance correlation use color difference signal prediction unit in FIG. 18 includes a luminance reference pixel reduction unit 931, a correlation calculation unit 932, and a color difference prediction image generation unit 933.

As shown in FIG. 19, the luminance reference pixel reduction unit 931, for the YUV 4: 2: 0 signal, a decoded luminance signal that is a decoded pixel value in the block corresponding to the prediction block of the color difference signal, The reduced luminance reference pixel Rec ′ _L is generated using the decoded luminance signal adjacent to the upper end and the left end of the decoded luminance signal.
Here, as shown in FIG. 20, the reduced luminance reference pixel Rec ′ _L is vertical to the luminance reference pixel Rec _L so that the YUV 4: 2: 0 signal has the same phase as the pixel of the color difference signal. After applying a low-pass filter of 1: 1, the sub-sampling is performed only on even columns in the vertical and horizontal directions.

式（１），（２）において、Ｉは処理対象となる色差信号の予測ブロックの１辺の画素数の２倍の値である。 When the luminance reference pixel reduction unit 931 generates the reduced luminance reference pixel Rec ′ _L , the correlation calculation unit 932 generates the reduced luminance reference pixel Rec ′ _L and the color difference signal adjacent to the upper end and the left end of the prediction block of the color difference signal. Correlation parameters α and β used for prediction are calculated using the color difference reference pixel Rec _C , which is the decoded pixel value, as shown in the following equations (1) and (2).

In equations (1) and (2), I is a value twice the number of pixels on one side of the prediction block of the color difference signal to be processed.

When the correlation calculation unit 932 calculates the correlation parameters α and β, the color difference predicted image generation unit 933 uses the correlation parameters α and β and the reduced luminance reference pixel Rec ′ _L as shown in the following equation (3). Then, the color difference prediction image Pred _C is generated.

J. Chen, et. Al, “CE6.a.4: Chroma intra prediction by reconstructed luma samples”, Joint Collaborative Team on Video Coding (JCT-VC) of ITU-T SG16 WP3 and ISO / IEC JTC1 / SC29 / WG11 , JCTVC-E266, 5th Meeting: Geneva, CH, Mar., 2011.

Since the conventional moving image coding apparatus is configured as described above, a change in the color difference signal that cannot be predicted from the adjacent pixels can be appropriately predicted using the correlation with the luminance signal, with high accuracy. Prediction becomes possible. However, when the reduced luminance reference pixel Rec ′ _L is generated, a strong low-pass filter is applied in the vertical direction of the screen by taking an average value of every two pixels, but simple in the horizontal direction of the screen. because only be subsampled every two pixels, there may aliasing occurs in the horizontal direction of the reduced luminance reference pixel Rec _'L. Since the color difference prediction image Pred _C is obtained by multiplying the reduced luminance reference pixel Rec ′ _L by scalar multiplication and offset addition, the aliasing of the reduced luminance reference pixel Rec ′ _L is reflected in the color difference prediction image and the prediction error is amplified. As a result, there has been a problem that improvement in coding efficiency is limited.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a moving picture coding apparatus and a moving picture coding method capable of suppressing the occurrence of aliasing and improving the coding efficiency. And
It is another object of the present invention to obtain a moving picture decoding apparatus and a moving picture decoding method that can accurately decode a moving picture from encoded data whose encoding efficiency is improved.

  The moving picture coding apparatus according to the present invention determines the maximum size of a coding block that is a processing unit of prediction processing, and determines the upper limit number of layers when the coding block of the maximum size is hierarchically divided. An encoding control unit that selects an encoding mode corresponding to each encoding block divided hierarchically from one or more of the available encoding modes, and an input image is determined by the encoding control unit The encoded block is divided into a maximum size encoded block, and the encoded block is divided by the block dividing means and the block dividing means until the maximum number of hierarchies determined by the encoding control means is reached. Predictive image generating means for generating a predictive image by performing prediction processing corresponding to the encoding mode selected by the encoding control means on the encoded block The difference image generation means for generating a difference image between the encoded block divided by the block division means and the prediction image generated by the prediction image generation means, and the difference image generated by the difference image generation means are compressed, Image compression means for outputting compressed data of the difference image, variable length coding of the compressed data output from the image compression means and the coding mode selected by the coding control means, and the compressed data and the coding of the coding mode Variable length encoding means for generating a bit stream in which the encoded data is multiplexed, and the predicted image generation means performs intra-frame prediction of the luminance component in the encoded block divided by the block dividing means, Among the luminance component intra prediction means for generating a predicted image for the luminance component and the pixels constituting the coding block, By smoothing the luminance component of a plurality of pixels adjacent in the horizontal direction and the vertical direction, a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component is calculated, and the correlation parameter and the luminance after smoothing are calculated. The color difference component intra prediction means for generating a prediction image for the color difference component using the components is configured.

  According to this invention, the predicted image generating means performs intra-frame prediction of the luminance component in the encoded block divided by the block dividing means, and generates a predicted image for the luminance component, the luminance component intra prediction means, A correlation parameter indicating the correlation between the smoothed luminance component and the color difference component is smoothed by smoothing the luminance component of a plurality of pixels adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block. It is composed of a chrominance component intra prediction means that generates a predicted image for the chrominance component using the calculated correlation parameter and the smoothed luminance component, thereby suppressing aliasing in the smoothed luminance component Thus, the encoding efficiency can be increased.

It is a block diagram which shows the moving image encoder by Embodiment 1 of this invention. It is a flowchart which shows the processing content of the moving image encoder by Embodiment 1 of this invention. It is a block diagram which shows the intra estimation part 4 of the moving image encoder by Embodiment 1 of this invention. It is a block diagram which shows the brightness | luminance correlation utilization color difference signal prediction part 24 of the moving image encoder by Embodiment 1 of this invention. It is a flowchart which shows the processing content of the intra estimation part 4 of the moving image encoder by Embodiment 1 of this invention. It is a flowchart which shows the processing content of the brightness | luminance correlation utilization color difference signal prediction part 24 of the moving image encoder by Embodiment 1 of this invention. It is a block diagram which shows the moving image decoding apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing content of the moving image decoding apparatus by Embodiment 1 of this invention. It is a block diagram which shows the intra estimation part 43 of the moving image decoding apparatus by Embodiment 1 of this invention. It is a block diagram which shows the brightness | luminance correlation utilization color difference signal prediction part 54 of the moving image decoding apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows a mode that the encoding block of the largest size is divided | segmented into a some encoding block hierarchically. It is an explanatory view showing a partition P _i ⁿ that belong to the coding block B ^n. It is explanatory drawing which shows the distribution of the partition after a division | segmentation, and the condition where the encoding mode m ( ^Bn ) is allocated to the partition after a hierarchy division | segmentation with a quadtree graph. Is an explanatory diagram showing an example of the coding block B ⁿ belonging selectable intra prediction parameters in each partition P _i ⁿ (intra prediction mode). It is explanatory drawing which shows an example of the pixel used when producing | generating the predicted value of the pixel in partition P _i ⁿ in the case of l _i ⁿ = m _i ⁿ = 4. It is explanatory drawing which shows the example of a response | compatibility of the intra prediction parameter of a color difference signal, and a color difference intra prediction mode. It is an explanatory view showing a method of generating a reduced luminance reference pixel Rec _'L. It is a block diagram which shows the brightness | luminance correlation utilization color difference signal estimation part which implements the prediction process of Intra_LM mode. It is explanatory drawing which shows the prediction block of a color difference signal, a decoded luminance signal, etc. It is an explanatory view showing a method of generating a reduced luminance reference pixel Rec _'L.

Embodiment 1 FIG.
1 is a block diagram showing a moving picture coding apparatus according to Embodiment 1 of the present invention.
In FIG. 1, an encoding control unit 1 determines the maximum size of an encoding block that is a processing unit when intra prediction processing (intraframe prediction processing) or motion compensation prediction processing (interframe prediction processing) is performed. Then, a process of determining the upper limit number of layers when the encoding block of the maximum size is hierarchically divided is performed.
In addition, the encoding control unit 1 assigns each encoding block divided hierarchically from one or more available encoding modes (one or more intra encoding modes and one or more inter encoding modes). A process of selecting a suitable encoding mode is performed.
In addition, the encoding control unit 1 determines the quantization parameter and transform block size used when the difference image is compressed for each encoding block, and intra prediction used when the prediction process is performed. A process of determining a parameter or an inter prediction parameter is performed. The quantization parameter and the transform block size are included in the prediction difference coding parameter, and are output to the transform / quantization unit 7, the inverse quantization / inverse transform unit 8, the variable length coding unit 13, and the like.
The encoding control unit 1 constitutes an encoding control unit.

When a video signal indicating an input image (current picture) is input, the block dividing unit 2 divides the input image into encoded blocks of the maximum size determined by the encoding control unit 1 and determined by the encoding control unit 1 The process of dividing the encoded block hierarchically is performed until the upper limit number of hierarchies is reached. The block dividing unit 2 constitutes block dividing means.
If the coding mode selected by the coding control unit 1 is the intra coding mode, the changeover switch 3 outputs the coding block divided by the block dividing unit 2 to the intra prediction unit 4, and the coding control unit 1 If the coding mode selected by (2) is the inter coding mode, a process of outputting the coding block divided by the block dividing unit 2 to the motion compensation prediction unit 5 is performed.

When the intra prediction unit 4 receives the encoded block divided by the block dividing unit 2 from the changeover switch 3, the intra prediction unit 4 is adjacent to the encoded block stored in the intra prediction memory 10 with respect to the encoded block. The process which produces | generates a prediction image is implemented by implementing the intra prediction process based on the intra prediction parameter output from the encoding control part 1 using the decoded pixel which is.
That is, the intra prediction unit 4 performs intra-frame prediction of the luminance component of the encoded block divided by the block dividing unit 2 to generate a prediction image for the luminance component.
On the other hand, for the color difference component in the coding block divided by the block dividing unit 2, if the coding mode selected by the coding control unit 1 is the directional prediction mode in the intra coding mode, the block dividing unit 2 Intra-frame prediction of the color difference component in the encoded block divided by the above is performed, and a predicted image for the color difference component is generated.
In addition, if the encoding mode selected by the encoding control unit 1 is the smoothed luminance correlation-use color difference signal prediction mode in the intra encoding mode, the horizontal direction and the pixel in the encoding block are Smooths the luminance component of multiple pixels adjacent in the vertical direction, calculates a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component, and uses the correlation parameter and the luminance component after smoothing. Thus, a predicted image for the color difference component is generated.

When the inter coding mode is selected by the coding control unit 1 as the coding mode corresponding to the coding block divided by the block dividing unit 2, the motion compensated prediction unit 5 is stored by the motion compensated prediction frame memory 12. Based on the inter prediction parameter output from the encoding control unit 1, using a reference image of one or more frames, a process for generating a predicted image is performed by performing a motion compensation prediction process for the encoded block To do.
The changeover switch 3, the intra prediction unit 4, and the motion compensation prediction unit 5 constitute a predicted image generation unit.

The subtracting unit 6 subtracts the prediction image generated by the intra prediction unit 4 or the motion compensation prediction unit 5 from the encoded block divided by the block dividing unit 2, thereby obtaining a difference image (= encoded block−predicted image). The process to generate is performed. The subtracting unit 6 constitutes a difference image generating unit.
The transform / quantization unit 7 performs transform processing (for example, DCT (discrete) of the difference image generated by the subtraction unit 6 in units of transform block size included in the prediction difference encoding parameter output from the encoding control unit 1. (Cosine transform), DST (discrete sine transform), orthogonal transform processing such as KL transform in which a base design is made in advance for a specific learning sequence), and the quantum included in the prediction differential encoding parameter By quantizing the transform coefficient of the difference image using the quantization parameter, a process of outputting the quantized transform coefficient as compressed data of the difference image is performed. The transform / quantization unit 7 constitutes an image compression unit.

  The inverse quantization / inverse transform unit 8 performs inverse quantization on the compressed data output from the transform / quantization unit 7 using the quantization parameter included in the prediction difference encoding parameter output from the encoding control unit 1. And inverse transform processing of the compressed data after inverse quantization (for example, inverse DCT (inverse discrete cosine transform) or inverse DST (inverse discrete sine transform)) in units of transform block sizes included in the prediction differential encoding parameter. (Inverse transform process such as inverse KL transform) is performed, and the process of outputting the compressed data after the inverse transform process as a local decoded prediction difference signal is performed.

The adding unit 9 adds the local decoded prediction difference signal output from the inverse quantization / inverse transform unit 8 and the prediction signal indicating the prediction image generated by the intra prediction unit 4 or the motion compensation prediction unit 5 to thereby perform local decoding. A process of generating a locally decoded image signal indicating an image is performed.
The intra prediction memory 10 is a recording medium such as a RAM that stores a local decoded image indicated by the local decoded image signal generated by the adding unit 9 as an image used in the next intra prediction process by the intra prediction unit 4.

The loop filter unit 11 compensates for the coding distortion included in the locally decoded image signal generated by the adding unit 9, and performs motion compensation prediction using the locally decoded image indicated by the locally decoded image signal after the coding distortion compensation as a reference image. A process of outputting to the frame memory 12 is performed.
The motion compensated prediction frame memory 12 is a recording medium such as a RAM that stores a locally decoded image after the filtering process by the loop filter unit 11 as a reference image used in the next motion compensated prediction process by the motion compensated prediction unit 5.

  The variable length encoding unit 13 includes the compressed data output from the transform / quantization unit 7, the encoding mode and prediction differential encoding parameter output from the encoding control unit 1, and the intra output from the intra prediction unit 4. The prediction parameter or the inter prediction parameter output from the motion compensation prediction unit 5 is variable-length encoded, and the compressed data, the encoding mode, the prediction differential encoding parameter, and the intra prediction parameter / inter prediction parameter encoded data are multiplexed. A process for generating a converted bitstream is performed. The variable length encoding unit 13 constitutes variable length encoding means.

In FIG. 1, a coding control unit 1, a block division unit 2, a changeover switch 3, an intra prediction unit 4, a motion compensation prediction unit 5, a subtraction unit 6, and a transform / quantization unit 7, which are components of the moving image coding apparatus. , The inverse quantization / inverse transform unit 8, the adder unit 9, the loop filter unit 11 and the variable length coding unit 13 each have dedicated hardware (for example, a semiconductor integrated circuit on which a CPU is mounted, or a one-chip microcomputer) However, when the moving image encoding apparatus is configured by a computer or the like, the encoding control unit 1, the block division unit 2, the changeover switch 3, the intra prediction unit 4, the motion A program describing the processing contents of the compensation prediction unit 5, the subtraction unit 6, the transformation / quantization unit 7, the inverse quantization / inverse transformation unit 8, the addition unit 9, the loop filter unit 11 and the variable length coding unit 13. All or part Stored in the memory of the computer, CPU of the computer may execute a program stored in the memory.
FIG. 2 is a flowchart showing the processing contents of the moving picture coding apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a block diagram showing the intra prediction unit 4 of the moving picture coding apparatus according to Embodiment 1 of the present invention.
In FIG. 3, the luminance signal intra prediction unit 21 performs intra-frame prediction of the luminance component in the encoded block divided by the block dividing unit 2 and performs a process of generating a prediction image for the luminance component.
That is, the luminance signal intra prediction unit 21 refers to the decoded luminance reference pixel adjacent to the encoded block stored in the intra prediction memory 10 and outputs the intra prediction output from the encoding control unit 1. By performing intra-frame prediction of the luminance component based on the parameter, a process for generating a predicted image for the luminance component is performed. The luminance signal intra prediction unit 21 constitutes luminance component intra prediction means.

  If the parameter indicating the intra coding mode of the chrominance signal indicates the directional prediction mode among the intra prediction parameters output from the coding control unit 1, the changeover switch 22 selects a reference pixel used for prediction. If the color difference signal directivity intra prediction unit 23 indicates that the parameter indicating the intra coding mode of the color difference signal is the smoothed luminance correlation use color difference signal prediction mode, the reference pixel used for prediction is used for the luminance correlation use. A process of outputting to the color difference signal prediction unit 24 is performed.

The chrominance signal directivity intra prediction unit 23 refers to the decoded chrominance reference pixel adjacent to the encoded block received from the changeover switch 22 and determines the chrominance based on the intra prediction parameter output from the encoding control unit 1. By performing intra-frame prediction of components, a process of generating a predicted image for the color difference component is performed.
The luminance correlation utilization color difference signal prediction unit 24, among the decoded pixels received from the changeover switch 22, has decoded luminance reference pixels and color difference reference pixels adjacent to the coding block, and has been decoded within the coding block. Using the luminance reference pixel, smoothing the luminance component related to a plurality of pixels adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block, A correlation parameter indicating the correlation of the color difference component is calculated, and a process of generating a predicted image for the color difference component is performed using the correlation parameter and the smoothed luminance component.
The changeover switch 22, the color difference signal directivity intra prediction unit 23, and the luminance correlation use color difference signal prediction unit 24 constitute a color difference component intra prediction unit.

FIG. 4 is a block diagram showing the luminance correlation utilizing color difference signal prediction unit 24 of the moving picture coding apparatus according to Embodiment 1 of the present invention.
In FIG. 4, the smoothed luminance reference pixel reducing unit 31 is adjacent in the horizontal direction and the vertical direction among the decoded luminance reference pixels constituting the encoded block stored in the intra prediction memory 10. A reduced luminance reference pixel Rec ′ _L is generated by performing smoothing processing or the like of a plurality of luminance reference pixels.
The correlation calculation unit 32 uses the color difference reference pixels stored in the intra prediction memory 10 and the reduced luminance reference pixel Rec ′ _L generated by the smoothed luminance reference pixel reduction unit 31 to calculate the correlation between the luminance component and the color difference component. Processing for calculating the correlation parameters α and β shown in FIG.

The color difference predicted image generation unit 33 uses the correlation parameters α and β calculated by the correlation calculation unit 32 and the reduced luminance reference pixel Rec ′ _L generated by the smoothed luminance reference pixel reduction unit 31 to generate a predicted image for the color difference component. Perform the process to generate.
FIG. 5 is a flowchart showing the processing contents of the intra prediction unit 4 of the moving picture coding apparatus according to Embodiment 1 of the present invention.
FIG. 6 is a flowchart showing the processing contents of the luminance correlation utilizing color difference signal prediction unit 24 of the moving picture coding apparatus according to Embodiment 1 of the present invention.

FIG. 7 is a block diagram showing a moving picture decoding apparatus according to Embodiment 1 of the present invention.
In FIG. 7, the variable length decoding unit 41 is a code that is hierarchically divided from the maximum size of the coding block that is a processing unit when the intra prediction process or the motion compensation prediction process is performed, and the coding block of the maximum size. By specifying the number of hierarchized block levels, the coded data related to the largest size coded block and the hierarchically divided coded block is identified from the coded data multiplexed in the bitstream. Then, from each encoded data, the compressed data, the encoding mode, the prediction differential encoding parameter, and the intra prediction parameter / inter prediction parameter related to the encoding block are subjected to variable length decoding, and the compressed data and the prediction differential encoding parameter are obtained. In addition to the output to the inverse quantization / inverse transform unit 45, the encoding mode and intra prediction parameters / inter prediction And it carries out a process of outputting the parameter to the changeover switch 42. The variable length decoding unit 41 constitutes variable length decoding means.

  The changeover switch 42 outputs the intra prediction parameter output from the variable length decoding unit 41 to the intra prediction unit 43 when the coding mode related to the coding block output from the variable length decoding unit 41 is the intra coding mode. When the coding mode is the inter coding mode, a process of outputting the inter prediction parameter output from the variable length decoding unit 41 to the motion compensation unit 44 is performed.

The intra prediction unit 43 uses a decoded pixel adjacent to the coding block stored in the intra prediction memory 47 and uses the decoded prediction frame output from the changeover switch 42 to generate a frame for the coding block. A process for generating a predicted image is performed by performing the intra prediction process.
That is, for the luminance component in the encoded block output from the variable length decoding unit 41, the intra prediction unit 43 performs intra-frame prediction of the luminance component to generate a prediction image for the luminance component.
On the other hand, for the color difference component in the coding block output from the variable length decoding unit 41, if the coding mode output from the variable length decoding unit 41 is the directional prediction mode in the intra coding mode, the coding is performed. Intraframe prediction of the color difference component in the block is performed to generate a predicted image for the color difference component.
Further, if the coding mode output from the variable length decoding unit 41 is the smoothed luminance correlation utilization color difference signal prediction mode in the intra coding mode, among the pixels constituting the coding block, the horizontal direction and Smooths the luminance component of multiple pixels adjacent in the vertical direction, calculates a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component, and uses the correlation parameter and the luminance component after smoothing. Thus, a predicted image for the color difference component is generated.

The motion compensation unit 44 performs a motion compensation prediction process on the encoded block based on the inter prediction parameter output from the changeover switch 42 using one or more reference images stored in the motion compensation prediction frame memory 49. Thus, a process for generating a predicted image is performed.
The changeover switch 42, the intra prediction unit 43, and the motion compensation unit 44 constitute a predicted image generation unit.

  The inverse quantization / inverse transform unit 45 uses the quantization parameter included in the prediction difference encoding parameter output from the variable length decoding unit 41 to compress the encoded block output from the variable length decoding unit 41 Data is inversely quantized, and inverse transform processing (for example, inverse DCT (Inverse Discrete Cosine Transform) or inverse DST (Inverse Discrete Discrete) is performed on the inverse quantization compressed data in units of transform block sizes included in the prediction differential encoding parameter. By performing (sine conversion), inverse conversion processing such as inverse KL conversion), a process of outputting the compressed data after the inverse conversion process as a decoded prediction difference signal (a signal indicating a difference image before compression) is performed. The inverse quantization / inverse transform unit 45 constitutes a difference image generation unit.

The addition unit 46 adds the decoded prediction difference signal output from the inverse quantization / inverse conversion unit 45 to the prediction signal indicating the prediction image generated by the intra prediction unit 43 or the motion compensation unit 44, thereby indicating a decoded image. A process of generating a decoded image signal is performed. The adding unit 46 constitutes a decoded image generating unit.
The intra prediction memory 47 is a recording medium such as a RAM that stores a decoded image indicated by the decoded image signal generated by the addition unit 46 as an image used in the next intra prediction process by the intra prediction unit 43.

The loop filter unit 48 compensates for the coding distortion included in the decoded image signal generated by the adding unit 46, and uses the decoded image indicated by the decoded image signal after the coding distortion compensation as a reference image as a motion compensated prediction frame memory 49. And a process of outputting the decoded image as a reproduced image to the outside.
The motion compensated prediction frame memory 49 is a recording medium such as a RAM that stores a decoded image after the filtering process by the loop filter unit 48 as a reference image to be used by the motion compensation unit 44 in the next motion compensation prediction process.

In FIG. 7, a variable length decoding unit 41, a changeover switch 42, an intra prediction unit 43, a motion compensation unit 44, an inverse quantization / inverse transformation unit 45, an addition unit 46, and a loop filter unit 48, which are components of the video decoding device. Are assumed to be configured with dedicated hardware (for example, a semiconductor integrated circuit on which a CPU is mounted, or a one-chip microcomputer), but the moving picture decoding device is configured with a computer or the like. Of the program describing the processing contents of the variable length decoding unit 41, the changeover switch 42, the intra prediction unit 43, the motion compensation unit 44, the inverse quantization / inverse transformation unit 45, the addition unit 46, and the loop filter unit 48. All or part of the information is stored in the memory of the computer, and the CPU of the computer executes the program stored in the memory. There.
FIG. 8 is a flowchart showing the processing contents of the moving picture decoding apparatus according to Embodiment 1 of the present invention.

FIG. 9 is a block diagram showing the intra prediction unit 43 of the moving picture decoding apparatus according to Embodiment 1 of the present invention.
In FIG. 9, the luminance signal intra prediction unit 51 performs intra-frame prediction of the luminance component in the encoded block output from the variable length decoding unit 41, and performs processing to generate a prediction image for the luminance component.
That is, the luminance signal intra prediction unit 51 refers to the decoded luminance reference pixel adjacent to the encoded block stored in the intra prediction memory 47, and outputs the intra prediction output from the variable length decoding unit 41. By performing intra-frame prediction of the luminance component based on the parameter, a process for generating a predicted image for the luminance component is performed. Note that the luminance signal intra prediction unit 51 constitutes luminance component intra prediction means.

  If the parameter indicating the intra coding mode of the color difference signal indicates the directional prediction mode among the intra prediction parameters output from the variable length decoding unit 41, the changeover switch 52 selects the reference pixel used for prediction. If the parameter indicating the intra coding mode of the color difference signal given to the color difference signal directional intra prediction unit 53 indicates that the color difference signal prediction mode uses the smoothed luminance correlation, the reference pixel used for the prediction uses the luminance correlation. A process of outputting to the color difference signal prediction unit 54 is performed.

The chrominance signal directivity intra prediction unit 53 refers to the decoded chrominance reference pixel adjacent to the encoded block received from the changeover switch 52, and the chrominance based on the intra prediction parameter output from the variable length decoding unit 41 By performing intra-frame prediction of components, a process of generating a predicted image for the color difference component is performed.
Of the decoded pixels received from the changeover switch 52, the luminance correlation use color difference signal prediction unit 54 has decoded luminance reference pixels and color difference reference pixels adjacent to the encoded block, and has been decoded in the encoded block. Using the luminance reference pixel, smoothing the luminance component related to a plurality of pixels adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block, A correlation parameter indicating the correlation of the color difference component is calculated, and a process of generating a predicted image for the color difference component is performed using the correlation parameter and the smoothed luminance component.
The changeover switch 52, the color difference signal directivity intra prediction unit 53, and the luminance correlation utilization color difference signal prediction unit 54 constitute a color difference component intra prediction unit.

FIG. 10 is a block diagram showing the luminance correlation utilization color difference signal prediction unit 54 of the moving picture decoding apparatus according to Embodiment 1 of the present invention.
In FIG. 10, the smoothed luminance reference pixel reduction unit 61 is adjacent in the horizontal direction and the vertical direction among the decoded luminance reference pixels constituting the encoded block stored in the intra prediction memory 47. A reduced luminance reference pixel Rec ′ _L is generated by performing smoothing processing or the like of a plurality of luminance reference pixels.
The correlation calculation unit 62 uses the chrominance reference pixel stored in the intra prediction memory 47 and the reduced luminance reference pixel Rec ′ _L generated by the smoothed luminance reference pixel reduction unit 61 to calculate the correlation between the luminance component and the chrominance component. Processing for calculating the correlation parameters α and β shown in FIG.
The color difference predicted image generation unit 63 uses the correlation parameters α and β calculated by the correlation calculation unit 62 and the reduced luminance reference pixel Rec ′ _L generated by the smoothed luminance reference pixel reduction unit 61 to generate a predicted image for the color difference component. Perform the process to generate.

The moving picture coding apparatus according to the first embodiment adapts to local changes in the spatial and temporal directions of a video signal, divides the video signal into regions of various sizes, and performs intraframe / interframe adaptive coding. It is characterized by performing.
In general, video signals have the characteristic that the complexity of the signal changes locally in space and time, and when viewed spatially, comparison is made on a specific video frame, for example, sky or wall. A picture having uniform signal characteristics in a wide image area and a picture having a complicated texture pattern in a small image area may be mixed in a picture including a person or a fine texture.

Even in terms of time, the sky and the wall have small changes in the local pattern in the time direction, but moving people and objects have temporal and rigid movements, so the time changes. Is big.
The encoding process generates a prediction difference signal with low signal power and entropy by temporal and spatial prediction, and performs a process of reducing the overall code amount. However, the prediction parameter used for the prediction process is as large as possible. If it can be applied uniformly to the region, the code amount of the prediction parameter can be reduced.
On the other hand, if the same prediction parameter is applied to a large image region with respect to an image signal pattern having a large temporal and spatial change, a prediction error increases, and therefore the code amount of the prediction difference signal cannot be reduced. .
Therefore, it is desirable to reduce the power / entropy of the prediction difference signal even if the prediction target area is reduced and the data amount of the prediction parameter used for the prediction process is increased in an area where the temporal and spatial changes are large. .
In order to perform encoding processing adapted to the general characteristics of such a video signal, the moving image encoding apparatus according to the first embodiment hierarchically divides the video signal area from a predetermined maximum block size. And the structure which adapts a prediction process and the encoding process of a prediction difference for every division area is employ | adopted.

The video signal to be processed by the moving image coding apparatus according to the first embodiment is a color in an arbitrary color space such as a YUV signal composed of a luminance signal and two color difference signals, or an RGB signal output from a digital image sensor. In addition to the video signal, the video frame is an arbitrary video signal such as a monochrome image signal or an infrared image signal, in which the video frame is composed of a horizontal and vertical two-dimensional digital sample (pixel) sequence.
The gradation of each pixel may be 8 bits, or may be gradation such as 10 bits or 12 bits.
However, in the following description, it is assumed that the input video signal is a YUV signal unless otherwise specified. In addition, it is assumed that the two color difference components U and V are subsampled 4: 2: 0 format signals with respect to the luminance component Y.
The processing data unit corresponding to each frame of the video is referred to as “picture”. In the first embodiment, “picture” is described as a signal of a video frame that has been sequentially scanned (progressive scan). However, when the video signal is an interlace signal, the “picture” may be a field image signal which is a unit constituting a video frame.

Next, the operation will be described.
First, the processing contents of the moving picture encoding apparatus in FIG. 1 will be described.
First, the encoding control unit 1 determines the maximum size of an encoding block that is a processing unit when intra prediction processing (intraframe prediction processing) or motion compensation prediction processing (interframe prediction processing) is performed, The upper limit number of hierarchies when the maximum size coding block is hierarchically divided is determined (step ST1 in FIG. 2).

As a method of determining the maximum size of the encoded block, for example, a method of determining a size corresponding to the resolution of the input image for all the pictures can be considered.
In addition, the difference in complexity of local motion of the input image is quantified as a parameter, and the maximum size is determined to be a small value for pictures with intense motion, and the maximum size is determined to be a large value for pictures with little motion. And so on.
The upper limit of the number of hierarchies is set so that, for example, the more the input image moves, the deeper the number of hierarchies, so that finer motion can be detected. A way to do this is considered.

In addition, the encoding control unit 1 includes each encoding block divided hierarchically from one or more available encoding modes (M types of intra encoding modes and N types of inter encoding modes). Is selected (step ST2). The M types of intra coding modes prepared in advance will be described later.
However, when each coding block hierarchically divided by the block division unit 2 described later is further divided into partitions, it is possible to select a coding mode corresponding to each partition.
In the following description of the first embodiment, each encoded block is further divided into partitions.
Since the encoding mode selection method by the encoding control unit 1 is a known technique, a detailed description thereof will be omitted. For example, an encoding process for an encoding block is performed using any available encoding mode. There is a method in which coding efficiency is verified by performing and a coding mode having the best coding efficiency is selected from among a plurality of available coding modes.

Further, the encoding control unit 1 determines a quantization parameter and a transform block size used when the difference image is compressed for each partition included in each encoding block, and a prediction process is performed. Intra prediction parameters or inter prediction parameters used in the determination are determined.
The encoding control unit 1 outputs the prediction difference encoding parameter including the quantization parameter and the transform block size to the transform / quantization unit 7, the inverse quantization / inverse transform unit 8, and the variable length encoding unit 13. Moreover, a prediction difference encoding parameter is output to the intra estimation part 4 as needed.

When a video signal indicating an input image is input, the block dividing unit 2 divides the input image into encoded blocks of the maximum size determined by the encoding control unit 1 and the upper limit determined by the encoding control unit 1 The encoded block is divided hierarchically until the number of layers is reached. Further, the encoded block is divided into partitions (step ST3).
Here, FIG. 11 is an explanatory diagram showing a state in which the maximum-size encoded block is hierarchically divided into a plurality of encoded blocks.
In the example of FIG. 11, the coding block of the maximum size is the coding block B ⁰ of the 0th layer, and has a size of (L ⁰ , M ⁰ ) as a luminance component.
Further, in the example of FIG. 11, the encoding block B ⁿ is obtained by performing hierarchical division to a predetermined depth determined separately in a quadtree structure, starting from the encoding block B ⁰ having the maximum size. Yes.

At the depth n, the coding block B ⁿ is an image area of size (L ⁿ , M ⁿ ).
However, L ⁿ and M ⁿ may be the same or different, but the example of FIG. 11 shows the case of L ⁿ = M ⁿ .
Later, the size of the encoded block B ⁿ is defined as the size of the luminance component of the encoded block ^{B n (L n, M n} ).

Since the block division unit 2 performs quadtree division, (L ^{n + 1} , M ^{n + 1} ) = (L ⁿ / 2, M ⁿ / 2) always holds.
However, in a color video signal (4: 4: 4 format) in which all color components have the same number of samples, such as RGB signals, the size of all color components is (L ⁿ , M ⁿ ). When the 4: 2: 0 format is handled, the size of the corresponding color difference component coding block is (L ⁿ / 2, M ⁿ / 2).
Hereinafter, a coding mode that can be selected in the coding block B ⁿ in the n-th layer is denoted as m (B ⁿ ).

In the case of a color video signal composed of a plurality of color components, the encoding mode m (B ⁿ ) may be configured to use an individual mode for each color component, but hereinafter, unless otherwise specified, YUV The description will be made on the assumption that it indicates the coding mode for the luminance component of the coding block of the signal 4: 2: 0 format.
The coding mode m (B ⁿ ) includes one or more intra coding modes (collectively “INTRA”) and one or more inter coding modes (collectively “INTER”). As described above, the encoding control unit 1 selects an encoding mode with the highest encoding efficiency for the encoding block B ⁿ from all the encoding modes available for the picture or a subset thereof. .

As shown in FIG. 11, the coding block B ⁿ is further divided into one or more prediction processing units (partitions).
Hereinafter, a partition belonging to the coding block B ⁿ is ^denoted as P _i ⁿ (i: partition number in the nth layer). FIG. 12 is an explanatory diagram showing partitions P _i ⁿ belonging to the coding block B ⁿ .
How the partition P _i ⁿ belonging to the coding block B ⁿ is divided is included as information in the coding mode m (B ⁿ ).
All partitions P _i ⁿ are subjected to prediction processing according to the encoding mode m (B ⁿ ), but individual prediction parameters can be selected for each partition P _i ⁿ .

For example, the encoding control unit 1 generates a block division state as illustrated in FIG. 13 for the encoding block of the maximum size, and specifies the encoding block ^Bn .
The hatched portion in FIG. 13A shows the distribution of the partitions after the division, and FIG. 13B shows the situation in which the encoding mode m (B ⁿ ) is assigned to the partition after the hierarchical division in a quadtree graph. Show.
In FIG. 13B, nodes surrounded by squares indicate nodes (encoded blocks B ⁿ ) to which the encoding mode m (B ⁿ ) is assigned.

When the coding control unit 1 selects the intra coding mode (m (B ⁿ ) εINTRA), the changeover switch 3 performs intra prediction on the partition P _i ⁿ belonging to the coding block B ⁿ divided by the block dividing unit 2. When the coding control unit 1 selects the inter coding mode (m (B ⁿ ) ∈INTER), the partition P _i ⁿ belonging to the coding block B ⁿ is output to the motion compensation prediction unit 5. .

Intra prediction unit 4 receives the partition P _i ⁿ belonging from the changeover switch 3 to the coding block B ⁿ (step ST4), although specific processing contents will be described later, the intra prediction determined by the encoding control unit 1 Based on the parameters, intra prediction processing (P _i ⁿ ) is generated by performing intra prediction processing for each partition P _i ⁿ (step ST5).
Hereinafter, in this specification, P _i ⁿ represents a partition, and (P _i ⁿ ) represents a predicted image of the partition P _i ⁿ .

Intra prediction parameters used to generate the intra-prediction image (P _i ⁿ⁾ is also the moving picture decoding apparatus, it is necessary to generate exactly the same intra prediction image (P _i ^n), the variable length coding unit 13 Multiplexed into a bitstream.
Note that the number of intra prediction directions that can be selected as the intra prediction parameter may be configured to differ depending on the size of the block to be processed.
Since the efficiency of intra prediction decreases in a large size partition, the number of intra prediction directions that can be selected can be reduced, and the number of intra prediction directions that can be selected in a small size partition can be increased.
For example, a 4 × 4 pixel partition or an 8 × 8 pixel partition may be configured in 34 directions, a 16 × 16 pixel partition in 17 directions, a 32 × 32 pixel partition in 9 directions, or the like.

When the motion compensated prediction unit 5 receives the partition P _i ⁿ belonging to the coding block B ⁿ from the changeover switch 3 (step ST4), each of the partitions P _i is based on the inter prediction parameter determined by the coding control unit 1. By performing inter prediction processing for ⁿ , an inter predicted image (P _i ⁿ ) is generated (step ST6).
That is, the motion compensation prediction unit 5 uses the reference image of one or more frames stored in the motion compensation prediction frame memory 12, and based on the inter prediction parameter output from the encoding control unit 1, By performing the motion compensated prediction process for, an inter predicted image (P _i ⁿ ) is generated.
Inter prediction parameters used to generate the inter prediction image (P _i ⁿ⁾ is also the moving picture decoding apparatus, it is necessary to generate exactly the same inter-prediction image (P _i ^n), the variable length coding unit 13 Multiplexed into a bitstream.

When the subtraction unit 6 receives the prediction image (P _i ⁿ ) from the intra prediction unit 4 or the motion compensation prediction unit 5, the subtraction unit 6 predicts the prediction from the partition P _i ⁿ belonging to the encoded block B ⁿ divided by the block division unit 2. By subtracting the image (P _i ⁿ ), a prediction difference signal e _i ⁿ indicating the difference image is generated (step ST7).
When the subtraction unit 6 generates the prediction difference signal e _i ⁿ , the transform / quantization unit 7 generates the prediction difference in units of transform block size included in the prediction difference encoding parameter output from the encoding control unit 1. While performing transformation processing (for example, DCT (discrete cosine transformation), DST (discrete sine transformation), orthogonal transformation processing such as KL transformation in which a base design is made in advance for a specific learning sequence) on the signal e _i ⁿ . Then, by quantizing the transform coefficient of the prediction difference signal e _i ⁿ using the quantization parameter included in the prediction difference encoding parameter, the compressed data of the difference image that is the transform coefficient after quantization is obtained. The data is output to the inverse quantization / inverse transform unit 8 and the variable length coding unit 13 (step ST8).

  When receiving the compressed data from the transform / quantization unit 7, the inverse quantization / inverse transform unit 8 uses the quantization parameter included in the prediction difference coding parameter output from the coding control unit 1 to The compressed data is inversely quantized, and the inverse quantization processing (for example, inverse DCT (inverse discrete cosine transform) or inverse DST (discrete) is performed on the basis of the transform block size included in the prediction differential encoding parameter. By performing (sine transformation), inverse transformation processing such as inverse KL transformation), the compressed data after the inverse transformation processing is output to the adding unit 9 as a local decoded prediction difference signal (step ST9).

When the addition unit 9 receives the local decoded prediction difference signal from the inverse quantization / inverse transformation unit 8, the addition unit 9 and the prediction image (P _i ) generated by the intra prediction unit 4 or the motion compensation prediction unit 5. ⁿ ) to generate a locally decoded image signal indicating a locally decoded partition image or a locally decoded block image (hereinafter referred to as a “locally decoded image”) as a collection thereof. The locally decoded image signal is output to the loop filter unit 11 (step ST10).
The intra prediction memory 10 stores the local decoded image for use in intra prediction.

When the loop filter unit 11 receives the local decoded image signal from the adder unit 9, the loop filter unit 11 compensates for the encoding distortion included in the local decoded image signal, and the local decoded image indicated by the local decoded image signal after the encoding distortion compensation Is stored in the motion compensated prediction frame memory 12 as a reference image (step ST11).
Note that the filtering process by the loop filter unit 11 may be performed in units of the maximum encoded block or individual encoded blocks of the input local decoded image signal, or a local decoded image signal corresponding to a macroblock for one screen. It may be performed for one screen after the input.

The processes of steps ST4 to ST10 are repeated until the processes for the partitions P _i ⁿ belonging to all the encoded blocks B ⁿ divided by the block dividing unit 2 are completed (step ST12).
The variable length coding unit 13, the compressed data output from the transform / quantization unit 7, the coding mode and prediction differential coding parameter output from the coding control unit 1, and the intra prediction unit 4 output The intra-prediction parameter or the inter-prediction parameter output from the motion compensated prediction unit 5 is variable-length coded, and the compressed data, the coding mode, the prediction differential coding parameter, and the intra-prediction parameter / inter-prediction parameter encoded data are obtained. A multiplexed bit stream is generated (step ST13).

Next, the processing content of the intra estimation part 4 is demonstrated concretely.
FIG. 14 is an explanatory diagram showing an example of intra prediction parameters (intra prediction modes) that can be selected in each partition P _i ⁿ belonging to the coding block B ⁿ .
In the example of FIG. 14, the prediction direction vector corresponding to the intra prediction mode is shown, and the relative angle between the prediction direction vectors is designed to be smaller as the number of selectable intra prediction modes increases.

First, the luminance signal intra prediction unit 21 of the intra prediction unit 4 performs intra-frame prediction of the luminance component in the encoded block divided by the block dividing unit 2, and generates a prediction image for the luminance component (FIG. 5). Step ST21).
Hereinafter, the processing content of the luminance signal intra prediction unit 21 will be specifically described.
Here, the luminance signal intra prediction unit 21 of the intra prediction unit 4, based on the intra prediction parameters (intra prediction mode) for the luminance signal partitions P _i ^n, the intra processing for generating an intra prediction signal of the luminance signal described To do.
For convenience of explanation, the size of the partition P _i ⁿ is assumed to be l _i ⁿ × m _i ⁿ pixels.

FIG. 15 is an explanatory diagram illustrating an example of pixels used when generating predicted values of pixels in the partition P _i ⁿ when l _i ⁿ = m _i ⁿ = 4.
In the example of FIG. 15, the encoded upper partition pixels ((2 × l _i ⁿ +1) pixels) adjacent to the partition P _i ⁿ and the left partition pixels ((2 × m _i ⁿ )). Number of pixels) is used as a reference pixel for prediction, but the number of pixels used for prediction may be more or less than that shown in FIG.
Further, in the example of FIG. 15, pixels for one row or one column adjacent to each other are used for prediction, but pixels for two rows or two columns or more may be used for prediction. .

ただし、ｋは正のスカラ値である。 For example, when the index value of the intra prediction mode for the partition P _i ⁿ is 2 (average value prediction), the luminance signal intra prediction unit 21 calculates the average value of the adjacent pixels in the upper partition and the adjacent pixels in the left partition as the partition P _i. ^A predicted image is generated as a predicted value of a pixel in ⁿ .
If the index value of the intra prediction mode is other than 2 (average prediction), the prediction direction vector index value indicates v _p = (dx, dy) on the basis of, generating a prediction value of the pixel in the partition P _i ⁿ To do.
Assuming that the relative coordinates in the partition P _i ^{n of} the pixel (prediction target pixel) for which the prediction value is generated (the upper left pixel of the partition is the origin) is (x, y), the position of the reference pixel used for prediction is as follows: This is the intersection of L and adjacent pixels.

However, k is a positive scalar value.

When the reference pixel is at the integer pixel position, the integer pixel is set as the prediction value of the prediction target pixel. When the reference pixel is not located at the integer pixel position, an interpolation pixel generated from the integer pixel adjacent to the reference pixel is set as the predicted value.
In the example of FIG. 15, since the reference pixel is not located at the integer pixel position, the average value of two pixels adjacent to the reference pixel is used as the predicted value.
Note that an interpolation pixel may be generated not only from two adjacent pixels but also from two or more adjacent pixels, and used as a predicted value.

The luminance signal intra prediction unit 21 generates prediction pixels for all the pixels of the luminance signal in the partition P _i ⁿ in the same procedure, and outputs the generated intra prediction image (P _i ⁿ ).
As described above, the intra-prediction parameters used for generating the intra-predicted image (P _i ⁿ ) are output to the variable length coding unit 13 for multiplexing into the bitstream.

The changeover switch 22 of the intra prediction unit 4 determines whether the parameter indicating the intra coding mode of the color difference signal among the intra prediction parameters output from the coding control unit 1 is the directionality prediction mode, or uses smoothed luminance correlation. It is determined whether the color difference signal prediction mode is set (step ST22).
If the parameter indicating the intra coding mode of the chrominance signal indicates that it is the directional prediction mode, the changeover switch 22 gives the reference pixel used for prediction to the chrominance signal directional intra prediction unit 23, and If the parameter indicating the intra coding mode indicates that it is the smoothed luminance correlation utilization color difference signal prediction mode, the reference pixel used for the prediction is given to the luminance correlation utilization color difference signal prediction unit 24.
Here, FIG. 16 is an explanatory diagram showing a correspondence example between the intra prediction parameters of the color difference signal and the color difference intra prediction modes.
In the example of FIG. 16, when the color difference signal intra prediction parameter is “34”, a reference pixel used for prediction is given to the luminance correlation utilization color difference signal prediction unit 24, and the color difference signal intra prediction parameter is other than “34”. In some cases, reference pixels used for prediction are given to the color difference signal directional intra prediction unit 23.

Color difference signal directional intra-prediction unit 23 receives the reference pixels used for prediction from the changeover switch 22, with reference to the decoded chrominance reference pixels adjacent to the partition P _i ^n, output from the coding controller 1 By performing intra-frame prediction of the color difference component based on the intra prediction parameter thus generated, a predicted image for the color difference component is generated (step ST23).
The intra prediction target in the chrominance signal directional intra prediction unit 23 is a color difference signal, and the intra prediction target is different from the luminance signal intra prediction unit 21 which is a luminance signal, but the processing content of the intra prediction itself is the luminance signal intra prediction unit. 21. Therefore, by performing directional prediction, horizontal prediction, vertical prediction, DC prediction, etc., an intra prediction image of a color difference signal is generated.

When the luminance correlation utilization chrominance signal prediction unit 24 receives the reference pixel used for prediction from the changeover switch 22, the decoded luminance reference pixel and chrominance reference pixel adjacent to the partition P _i ⁿ which is the encoded block, and the partition decoded brightness reference pixels in P _i ⁿ (brightness reference pixels in the local decoded in an image obtained from the intra prediction image of the partition P _i ⁿ previously generated by the luminance signal intra prediction unit 21 (P _i ⁿ⁾⁾ Are used to smooth the luminance component of a plurality of pixels adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block, and the smoothed luminance component and color difference component A correlation parameter indicating the correlation is calculated, and a predicted image for the color difference component is generated using the correlation parameter and the smoothed luminance component (step ST24).
Hereinafter, the processing content of the luminance correlation utilization color difference signal prediction unit 24 will be specifically described.

Smoothing luminance correlation utilizing the color difference signal prediction section 24 brightness reference pixel reducing unit 31, partition P _i ⁿ structure to have decoded luminance reference pixels stored by the intra prediction memory 10 (the luminance signal intra prediction unit 21, among the luminance reference pixels in the local decoded image obtained from the intra-predicted image (P _i ⁿ ) of the partition P _i ⁿ generated in advance by 21, in the horizontal direction and the vertical direction. A reduced luminance reference pixel Rec ′ _L is generated by performing a pixel smoothing process or the like (step ST31 in FIG. 6).
That is, the smoothed luminance reference pixel reducing unit 31, as shown in FIG. 19, (in the figure, the block on the left side of N × N) prediction block of the color difference signals in the partition P _i ⁿ in the block (drawing corresponding to, A reduced luminance reference pixel using a decoded luminance signal which is a decoded pixel value in the right 2N × 2N block) and a decoded luminance signal adjacent to the upper end and the left end of the decoded luminance signal. Rec ′ _L is generated.
Here, as shown in FIG. 17, the reduced luminance reference pixel Rec ′ _L is arranged in the horizontal direction with respect to the luminance reference pixel Rec _L so that the YUV 4: 2: 0 signal has the same phase as the color difference signal pixel. After a 1: 2: 1 low-pass filter and a 1: 1 low-pass filter are applied in the vertical direction, only an even column is sub-sampled in the vertical and horizontal directions.

式（４），（５）において、Ｉは処理対象となる色差信号の予測ブロックの１辺の画素数の２倍の値である。 When the smoothed luminance reference pixel reducing unit 31 generates the reduced luminance reference pixel Rec ′ _L , the correlation calculating unit 32 of the luminance correlation using color difference signal predicting unit 24 generates the reduced luminance reference pixel Rec ′ _L and the prediction block of the color difference signal. Using the color difference reference pixel Rec _C , which is a decoded pixel value of the color difference signal adjacent to the upper end and the left end of the image, as shown in the following equations (4) and (5), α and β are calculated (step ST32).

In equations (4) and (5), I is a value twice the number of pixels on one side of the prediction block of the color difference signal to be processed.

When the correlation calculation unit 32 calculates the correlation parameters α and β, the color difference prediction image generation unit 33 uses the correlation parameters α and β and the reduced luminance reference pixel Rec ′ _L as shown in the following equation (6). Then, the color difference prediction image Pred _C is generated (step ST33).

Intra prediction is a means for predicting an unknown area in the screen from a known area, but the texture of the luminance signal and the color difference signal are correlated, and in the spatial direction, neighboring pixels change pixel values. Predictive efficiency by calculating the correlation parameter between the luminance signal and the color difference signal using the decoded luminance signal and the color difference signal adjacent to the prediction block and predicting the color difference signal from the luminance signal and the correlation parameter. Can be improved.
In this case, since the resolution of the luminance signal and the color difference signal is different in the YUV 4: 2: 0 signal, it is necessary to subsample the luminance signal. However, the occurrence of aliasing can be suppressed by applying a low-pass filter, and the prediction efficiency Can be improved.

  As described above, the variable length coding unit 13 performs variable length coding on the intra prediction parameter output from the intra prediction unit 4 and multiplexes the codeword of the intra prediction parameter into the bitstream. Is encoded, a representative prediction direction vector (prediction direction representative vector) is selected from prediction direction vectors of a plurality of directional predictions, and an intra prediction parameter is used as an index of the prediction direction representative vector (prediction direction representative). Index) and an index (prediction direction difference index) representing the difference from the prediction direction representative vector, and by performing Huffman coding such as arithmetic coding according to the probability model for each index, the code amount is You may comprise so that it may reduce and encode.

Next, processing contents of the moving picture decoding apparatus in FIG. 7 will be described.
When the variable length decoding unit 41 receives the bit stream generated by the moving picture encoding device in FIG. 1, the variable length decoding unit 41 performs variable length decoding processing on the bit stream (step ST41 in FIG. 8), and the picture of one frame or more The frame size is decoded in sequence units or picture units.
When the frame size is decoded, the variable length decoding unit 41 determines the maximum coding block size determined by the moving image coding apparatus in FIG. 1 (a code that is a processing unit when the intra prediction process or the motion compensation prediction process is performed). (The maximum size of the encoded block) and the upper limit of the number of division layers (the number of layers of the encoded block divided hierarchically from the encoded block of the maximum size) are determined in the same procedure as that of the video encoding device (step ST42).

For example, when the maximum size of the encoded block is determined to be the size corresponding to the resolution of the input image for all the pictures, the moving image shown in FIG. 1 is based on the previously decoded frame size. The maximum size of the encoded block is determined by the same procedure as that of the image encoding apparatus.
When the maximum size of the encoded block and the number of layers of the encoded block are multiplexed in the bitstream by the moving image encoding device, the maximum size of the encoded block and the number of layers of the encoded block from the bitstream Is decrypted.

The variable length decoding unit 41 determines the maximum size of the encoded block and the number of layers of the encoded block, and grasps the hierarchical division state of each encoded block from the maximum encoded block as a starting point. Among the encoded data multiplexed in the bit stream, the encoded data related to each encoded block is specified, and the encoding mode assigned to each encoded block is decoded from the encoded data.
Then, the variable-length decoding unit 41 refers to the division information of the partition P _i ⁿ that belong to coded blocks B ^n, which is included in the coding mode, in the coded data multiplexed in the bit stream in, it identifies the coded data according to each partition P _i ⁿ (step ST43).
Variable-length decoding unit 41, the compressed data from each partition P _i ⁿ encoded data according to the predictive differential coding parameters, intra prediction parameters / inter prediction parameters by variable length decoding, the compressed data and predictive differential coding parameters Is output to the inverse quantization / inverse transform unit 45, and the encoding mode and the intra prediction parameter / inter prediction parameter are output to the changeover switch 42 (step ST44).

For example, when the prediction direction representative index and the prediction direction difference index are multiplexed in the bitstream, the prediction direction representative index and the prediction direction difference index are entropy decoded by arithmetic decoding or the like according to each probability model, An intra prediction parameter is specified from the prediction direction representative index and the prediction direction difference index.
Thereby, even when the code amount of the intra prediction parameter is reduced on the moving image encoding device side, the intra prediction parameter can be correctly decoded.

Changeover switch 42, when the coding mode of the partition P _i ⁿ that belong to coded blocks B ⁿ output from the variable length decoding unit 41 is an intra coding mode, the intra prediction parameter output from the variable length decoding unit 41 Is output to the intra prediction unit 43, and when the encoding mode is the inter encoding mode, the inter prediction parameter output from the variable length decoding unit 41 is output to the motion compensation unit 44.

When the intra prediction unit 43 receives the intra prediction parameter from the variable length decoding unit 41 (step ST45), the intra prediction unit 43 performs intra prediction for each partition P _i ⁿ based on the intra prediction parameter, similarly to the intra prediction unit 4 in FIG. By performing the processing, an intra-predicted image (P _i ⁿ ) is generated (step ST46).
Hereinafter, the processing content of the intra estimation part 43 is demonstrated concretely.

Luminance signal intra prediction unit 51 of the intra prediction unit 43 receives the intra prediction parameter from the variable length decoding unit 41, similarly to the luminance signal intra prediction unit 21 of the video encoding apparatus, for example, intra against the partition P _i ⁿ If the index value of the prediction mode is 2 (average prediction), and generates a prediction image the mean value of neighboring pixels of the adjacent pixel and the left partition of the upper partition as the predicted value of the pixel in the partition P _i ^n.
If the index value of the intra prediction mode is other than 2 (average prediction), the prediction direction vector index value indicates v _p = (dx, dy) on the basis of, generating a prediction value of the pixel in the partition P _i ⁿ To do.
The luminance signal intra prediction unit 51 generates prediction pixels for all the pixels of the luminance signal in the partition P _i ⁿ in the same procedure, and outputs the generated intra prediction image (P _i ⁿ ).

The changeover switch 52 of the intra-prediction unit 43 is similar to the changeover switch 22 of the video encoding device, and the parameter indicating the intra-coding mode of the color difference signal among the intra-prediction parameters output from the variable-length decoding unit 41 is It is determined whether the mode is the directionality prediction mode or the smoothed luminance correlation utilization color difference signal prediction mode.
If the parameter indicating the intra coding mode of the chrominance signal indicates that it is the directional prediction mode, the changeover switch 52 provides the reference pixel used for prediction to the chrominance signal directional intra prediction unit 53, and If the parameter indicating the intra coding mode indicates that it is the smoothed luminance correlation utilization color difference signal prediction mode, the reference pixel used for the prediction is given to the luminance correlation utilization color difference signal prediction unit 54.

Color difference signal directional intra-prediction unit 53 receives the reference pixels used for prediction from the changeover switch 52, similarly to the color difference signals directional intra prediction unit 23 of the moving picture coding apparatus, adjacent to the partition P _i ⁿ By referring to the decoded chrominance reference pixel and performing intra-frame prediction of the chrominance component based on the intra prediction parameter output from the variable length decoding unit 41, a predicted image for the chrominance component is generated.
The intra prediction target in the chrominance signal directional intra prediction unit 53 is a color difference signal, and the intra prediction target is different from the luminance signal intra prediction unit 51, which is a luminance signal. Same as 51. Therefore, by performing directional prediction, horizontal prediction, vertical prediction, DC prediction, etc., an intra prediction image of a color difference signal is generated.

When receiving the reference pixel used for prediction from the changeover switch 52, the luminance correlation use color difference signal prediction unit 54 is adjacent to the partition P _i ⁿ , similarly to the luminance correlation use color difference signal prediction unit 24 of the video encoding device. decoded luminance reference pixel and the chrominance reference pixels, the partition P _i decoded brightness reference pixels in ⁿ (partition previously generated by the luminance signal intra prediction unit 51 P _i ⁿ intra predicted image (P _i ⁿ⁾ Luminance reference pixels in the decoded image obtained from (1)) and smoothing the luminance component of a plurality of pixels adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block. The correlation parameter indicating the correlation between the smoothed luminance component and the color difference component is calculated, and a predicted image for the color difference component is generated using the correlation parameter and the smoothed luminance component. That.
Hereinafter, the processing content of the luminance correlation utilization color difference signal prediction unit 54 will be specifically described.

Similar to the smoothed luminance reference pixel reducing unit 31 of the moving image encoding device, the smoothed luminance reference pixel reducing unit 61 of the luminance correlation use color difference signal predicting unit 54 stores the partition P _i stored in the intra prediction memory 47. Decoded luminance reference pixels constituting ⁿ (luminance reference pixels in the decoded image obtained from the intra prediction image (P _i ⁿ ) of the partition P _i ⁿ previously generated by the luminance signal intra prediction unit 51) Among them, the reduced luminance reference pixel Rec ′ _L is generated by performing smoothing processing or the like of a plurality of luminance reference pixels adjacent in the horizontal direction and the vertical direction.
That is, the smoothed luminance reference pixel reducing unit 61, as shown in FIG. 19, (in the figure, the block on the left side of N × N) prediction block of the color difference signals in the partition P _i ⁿ in the block (drawing corresponding to, A reduced luminance reference pixel using a decoded luminance signal which is a decoded pixel value in the right 2N × 2N block) and a decoded luminance signal adjacent to the upper end and the left end of the decoded luminance signal. Rec ′ _L is generated.
Here, as shown in FIG. 17, the reduced luminance reference pixel Rec ′ _L is arranged in the horizontal direction with respect to the luminance reference pixel Rec _L so that the YUV 4: 2: 0 signal has the same phase as the color difference signal pixel. After a 1: 2: 1 low-pass filter and a 1: 1 low-pass filter are applied in the vertical direction, only an even column is sub-sampled in the vertical and horizontal directions.

Correlation calculating unit 62 'when generating _L, and the like the correlation calculating unit 32 of the moving picture coding apparatus, the reduced luminance reference pixel Rec' smoothed luminance reference pixel reducing unit 61 reduces the luminance reference pixels Rec and _L, As shown in the above equations (4) and (5), prediction is performed using the color difference reference pixel Rec _C which is a decoded pixel value of the color difference signal adjacent to the upper end and the left end of the prediction block of the color difference signal. Correlation parameters α and β used in the above are calculated.
When the correlation calculation unit 62 calculates the correlation parameters α and β, the color difference predicted image generation unit 63 calculates the correlation parameters α and β and the reduced luminance reference pixel Rec as in the color difference prediction image generation unit 33 of the moving image encoding device. 'Using _L , a color difference prediction image Pred _C is generated as shown in the above equation (6).

Motion compensation unit 44 receives the inter prediction parameters from the changeover switch 42, similarly to the motion compensation prediction unit 5 of the moving picture coding apparatus, on the basis of the inter prediction parameter, the inter prediction processing for each partition P _i ⁿ By performing, an inter prediction image (P _i ⁿ ) is generated (step ST47).
That is, the motion compensation unit 44 performs a motion compensation prediction process on the partition P _i ⁿ based on the inter prediction parameter using one or more reference images stored in the motion compensation prediction frame memory 49, An inter prediction image (P _i ⁿ ) is generated.

  When the inverse quantization / inverse transform unit 45 receives the prediction difference encoding parameter from the variable length decoding unit 41, the inverse quantization / inverse conversion unit 45 outputs the prediction difference encoding parameter from the variable length decoding unit 41 using the quantization parameter included in the prediction difference encoding parameter. The compressed data related to the encoded block is dequantized, and the inverse transformed process of the compressed data after inverse quantization (for example, inverse DCT (inverse discrete) is performed in the transform block size unit included in the prediction differential encoding parameter. (Cosine transform), inverse DST (inverse discrete sine transform), inverse transform process such as inverse KL transform), and the like, the compressed data after the inverse transform process is decoded and decoded differential signal (a signal indicating a differential image before compression) To the adder 46 (step ST48).

The addition unit 46 adds the decoded prediction difference signal output from the inverse quantization / inverse conversion unit 45 and the prediction signal indicating the prediction image (P _i ⁿ ) generated by the intra prediction unit 43 or the motion compensation unit 44. Thus, a decoded image signal indicating a decoded partition image or a decoded image as a collection thereof is generated, and the decoded image signal is output to the loop filter unit 48 (step ST49).
The intra prediction memory 47 stores the decoded image for use in intra prediction.

When the loop filter unit 48 receives the decoded image signal from the adder unit 46, the loop filter unit 48 compensates for the encoding distortion included in the decoded image signal, and uses the decoded image indicated by the decoded image signal after the encoding distortion compensation as a reference image. While storing in the motion compensation prediction frame memory 49, the decoded image is output as a reproduced image (step ST50).
Note that the filtering processing by the loop filter unit 48 may be performed for the maximum encoded block of the input decoded image signal or for each individual encoded block, or a decoded image signal corresponding to a macroblock for one screen is input. After being done, it may be performed for one screen at a time.
Processing in step ST43~ST49 is repeated until the processing for the partitions P _i ⁿ that belong to all the coding blocks B ⁿ is completed (step ST51).

As is apparent from the above, according to the first embodiment, the intra prediction unit 4 of the moving image encoding device uses the horizontal direction among the pixels constituting the encoded block divided by the block dividing unit 2. And smoothing the luminance component of a plurality of pixels adjacent in the vertical direction, calculating a correlation parameter indicating a correlation between the smoothed luminance component and the color difference component, and calculating the correlation parameter and the luminance component after smoothing. Thus, since the prediction image for the color difference component is generated, it is possible to suppress the occurrence of aliasing in the luminance component after smoothing and increase the encoding efficiency.
That is, when the encoding mode selected by the encoding control unit 1 is the intra prediction mode, and the parameter indicating the intra prediction mode of the color difference signal indicates that the color difference signal prediction mode is a smoothed luminance correlation use color mode, Reduced luminance reference pixels are generated by smoothing the luminance reference pixels in the horizontal and vertical directions and sub-sampling, and an intra prediction image of the color difference signal is generated using the correlation between the luminance signal and the color difference signal. Therefore, a prediction image in which amplification of a prediction error due to aliasing, which has been conventionally generated, is suppressed and the prediction efficiency is improved, and as a result, encoding efficiency can be increased.

Further, according to the first embodiment, the intra prediction unit 43 of the video decoding device is adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block output from the variable length decoding unit 41. Smoothing luminance components related to a plurality of pixels, calculating a correlation parameter indicating a correlation between the smoothed luminance component and the color difference component, and using the correlation parameter and the luminance component after smoothing, the color difference component Therefore, it is possible to accurately decode a moving image from encoded data whose encoding efficiency is improved.
That is, the coding mode that is variable-length decoded by the variable-length decoding unit 41 is the intra prediction mode, and the parameter indicating the intra prediction mode of the color difference signal indicates that the color difference signal prediction mode uses the smoothed luminance correlation. In this case, the luminance reference pixel is smoothed in the horizontal direction and the vertical direction and sub-sampled to generate a reduced luminance reference pixel, and the intra prediction image of the color difference signal using the correlation between the luminance signal and the color difference signal Therefore, a moving image can be accurately decoded from encoded data whose encoding efficiency is improved.

In the first embodiment, when a reduced luminance reference pixel is generated, a 1: 2: 1 smoothing filter is applied in the horizontal direction. However, the filter coefficient is not limited to this. For example, a filter such as 3: 2: 3, 7: 2: 7, 1: 0: 1, a smoothing filter with a larger number of taps, or a 1: 1 filter can achieve the same effect. Can be obtained.
In the first embodiment, when a reduced luminance reference pixel is generated, a common one is used as a smoothing filter for the luminance reference pixel of the block to be predicted and the luminance reference pixel adjacent thereto. Even if different filters are applied, the 1: 0: 1 filter is applied to the luminance reference pixels of the block to be predicted, and the 1: 2: 1 filter is applied to the adjacent luminance reference pixels. The effect of can be obtained.
If a 1: 0: 1 filter or a 1: 1 filter is applied, the amount of calculation can be reduced. On the other hand, if a smoothing filter having a large number of taps is applied, the encoding efficiency is improved. Can be obtained.
Further, the smoothing in the horizontal direction and the vertical direction may be performed simultaneously. For example, the average value may be calculated after weighted addition of six target pixels according to the filter coefficient.

  In the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.

  DESCRIPTION OF SYMBOLS 1 Coding control part (coding control means), 2 block division part (block division means), 3 changeover switch (prediction image generation means), 4 intra prediction part (prediction image generation means), 5 motion compensation prediction part (prediction) Image generation means), 6 subtraction section (difference image generation means), 7 transform / quantization section (image compression means), 8 inverse quantization / inverse transform section, 9 addition section, 10 intra prediction memory, 11 loop filter section , 12 motion compensated prediction frame memory, 13 variable length coding unit (variable length coding unit), 21 luminance signal intra prediction unit (luminance component intra prediction unit), 22 changeover switch (color difference component intra prediction unit), 23 color difference signal Directional intra prediction unit (color difference component intra prediction means), 24 luminance correlation use color difference signal prediction unit (color difference component intra prediction means), 31 Smoothing luminance reference Element reduction unit, 32 correlation calculation unit, 33 color difference prediction image generation unit, 41 variable length decoding unit (variable length decoding unit), 42 changeover switch (prediction image generation unit), 43 intra prediction unit (prediction image generation unit), 44 Motion compensation unit (predicted image generating unit), 45 Inverse quantization / inverse transform unit (difference image generating unit), 46 Adder unit (decoded image generating unit), 47 Intra prediction memory, 48 loop filter unit, 49 Motion compensated prediction Frame memory, 51 luminance signal intra prediction unit (luminance component intra prediction unit), 52 changeover switch (color difference component intra prediction unit), 53 color difference signal directional intra prediction unit (color difference component intra prediction unit), 54 luminance correlation use color difference signal Prediction unit (color difference component intra prediction means), 61 smoothed luminance reference pixel reduction unit, 62 correlation calculation unit, 63 color difference prediction image Generating unit, 931 luminance reference pixel reducing unit, 932 correlation calculation unit, 933-color difference prediction image generation unit.

Claims (6)

One or more encoding modes that can be used by determining the maximum size of an encoding block that is a processing unit of prediction processing, and determining the upper limit number of layers when the encoding block of the maximum size is hierarchically divided Coding control means for selecting a coding mode corresponding to each coding block divided hierarchically, and an input image is divided into coding blocks of the maximum size determined by the coding control means. And the block dividing means for dividing the encoded block hierarchically until reaching the upper limit number of layers determined by the encoding control means, and the encoded block divided by the block dividing means, A prediction image generating unit that generates a prediction image by performing a prediction process corresponding to the encoding mode selected by the encoding control unit; A difference image generating means for generating a difference image between the encoded block divided by the means and a predicted image generated by the predicted image generating means; a difference image generated by the difference image generating means; Image compression means for outputting compressed data of the image, variable length coding of the compressed data output from the image compression means and the coding mode selected by the coding control means, and the compressed data and the coding mode Variable length encoding means for generating a bit stream in which the encoded data is multiplexed,
The predicted image generation unit performs intra-frame prediction of the luminance component in the encoded block divided by the block dividing unit, and generates a predicted image for the luminance component. The luminance component intra prediction unit and the encoded block Smoothing the luminance component related to a plurality of pixels adjacent in the horizontal direction and the vertical direction among the constituent pixels, calculating a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component, and A moving picture coding apparatus comprising: a color difference component intra prediction means for generating a predicted image for a color difference component using a correlation parameter and a smoothed luminance component. If the coding mode selected by the coding control means is a directional prediction mode in the intra coding mode, the chrominance component intra prediction means performs intra-frame prediction of the chrominance component in the coding block divided by the block dividing means. To generate a prediction image for the color difference component,
If the coding mode selected by the coding control means is the smoothed luminance correlation utilization color difference signal prediction mode in the intra coding mode, the horizontal direction and the vertical direction among the pixels constituting the coding block Smoothing the luminance component relating to a plurality of pixels adjacent to the pixel, calculating a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component, and using the correlation parameter and the luminance component after smoothing, The moving image encoding apparatus according to claim 1, wherein a prediction image for the color difference component is generated. Variable length decoding means for variable length decoding the compressed data and the coding mode for each coding block hierarchically divided from the encoded data multiplexed in the bitstream, and variable by the variable length decoding means Predictive image generating means for generating a predictive image by performing prediction processing corresponding to the encoding mode related to the encoded block for the long-decoded encoded block, and variable length decoding by the variable length decoding means A difference image generation unit that generates a difference image before compression from the compressed data relating to the encoded block, a difference image generated by the difference image generation unit, and a prediction image generated by the prediction image generation unit And a decoded image generating means for generating a decoded image,
The prediction image generation unit performs intra-frame prediction of the luminance component in the encoded block that has been variable-length decoded by the variable-length decoding unit, and generates a prediction image for the luminance component, the luminance component intra prediction unit, and the code Smoothes the luminance components of multiple pixels that are adjacent to each other in the horizontal and vertical directions, and calculates correlation parameters that indicate the correlation between the smoothed luminance and color difference components. And a color difference component intra prediction means for generating a predicted image for the color difference component using the correlation parameter and the smoothed luminance component. The chrominance component intra-prediction means, in the coding block that has been variable-length decoded by the variable-length decoding means, if the coding mode that has been variable-length decoded by the variable-length decoding means is a directional prediction mode in the intra-coding mode. Perform intra-frame prediction of chrominance components to generate a predicted image for chrominance components,
If the coding mode that has been variable-length decoded by the variable-length decoding means is the smoothed luminance correlation-use color difference signal prediction mode in the intra coding mode, among the pixels constituting the coding block, the horizontal direction and By smoothing the luminance component of a plurality of pixels adjacent in the vertical direction, a correlation parameter indicating the correlation between the smoothed luminance component and the color difference component is calculated, and the correlation parameter and the smoothed luminance component are used. The moving image decoding apparatus according to claim 3, further comprising: generating a predicted image for the color difference component. The encoding control means determines the maximum size of the encoding block that is the processing unit of the prediction process, and determines the upper limit number of layers when the encoding block of the maximum size is hierarchically divided and can be used. A coding control processing step for selecting a coding mode corresponding to each coding block that is hierarchically divided from one or more coding modes; and a block dividing means that converts the input image into the coding control processing. A block division processing step that divides the encoded block hierarchically until it reaches the upper limit number of layers determined in the encoding control processing step, and is divided into the maximum size encoded blocks determined in the step; The prediction image generating means applies the coding mode selected in the coding control processing step to the coding block divided in the block division processing step. A prediction image generation processing step for generating a prediction image by performing a prediction process corresponding to the code, and a difference image generation means generated by the encoded block divided in the block division processing step and the prediction image generation processing step. A difference image generation processing step for generating a difference image with the predicted image, and an image compression unit that compresses the difference image generated in the difference image generation processing step and outputs compressed data of the difference image A processing step and a variable-length encoding unit variable-length-encode the compressed data output in the image compression processing step and the encoding mode selected in the encoding control processing step, and the compressed data and the encoding A variable-length encoding processing step for generating a bitstream in which encoded data of a mode is multiplexed,
In the prediction image generation processing step, a luminance component intra prediction processing step for generating a prediction image for the luminance component by performing intra-frame prediction of the luminance component in the encoded block divided in the block division processing step, and the code Smoothes the luminance components of multiple pixels that are adjacent to each other in the horizontal and vertical directions, and calculates correlation parameters that indicate the correlation between the smoothed luminance and color difference components. And a color difference component intra prediction processing step of generating a predicted image for the color difference component using the correlation parameter and the smoothed luminance component. A variable-length decoding means, wherein the variable-length decoding means variable-length decodes the compressed data and the coding mode related to each coding block hierarchically divided from the coded data multiplexed in the bitstream; Prediction in which prediction image generation means generates a prediction image by performing prediction processing corresponding to the coding mode related to the coding block on the coding block that has been variable length decoded in the variable length decoding processing step. An image generation processing step, a difference image generation step in which the difference image generation means generates a difference image before compression from the compressed data related to the encoded block subjected to variable length decoding in the variable length decoding processing step; Means adds the difference image generated in the difference image generation processing step and the prediction image generated in the prediction image generation processing step And a decoded image generation processing step of generating a decoded image Te,
In the predicted image generation processing step, a luminance component intra prediction processing step that performs intra-frame prediction of the luminance component in the coding block variable-length decoded in the variable-length decoding processing step to generate a predicted image for the luminance component; The correlation indicating the correlation between the smoothed luminance component and the color difference component by smoothing the luminance component of a plurality of pixels adjacent in the horizontal direction and the vertical direction among the pixels constituting the coding block. A moving picture decoding method comprising: calculating a parameter, and performing a color difference component intra prediction processing step of generating a predicted image for the color difference component using the correlation parameter and the smoothed luminance component.

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