JP2015019257A - Color moving image coding device, color moving image decoding device, color moving image coding method and color moving image decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve coding efficiency of a luminance signal, a color difference signal or individual color components while a circuit scale is suppressed to be small when signals including much more color components than YUV4:4:4 signals, RGB signals and three primary colors are coded.SOLUTION: A prediction image generating section generates a prediction image by performing inter-frame prediction decoding on a color component except for a first color component with a decoded image having the color component which is the same as the color component of a decoding object, which is included in other decoded images, as a reference image, or generates the prediction image of the color component except for the first color component in the decoding object by performing the inter-frame prediction decoding by using a correlation parameter showing correlation between a pixel of the decoded image having the first color component included in the same decoded image, and a pixel of the decoding object having the color component except for the first color component in the decoding object, and the decoded image of the first color component.

Description

  The present invention relates to a color moving image encoding device and a color moving image encoding method for encoding a color moving image with high efficiency, a color moving image decoding device for decoding a color moving image encoded with high efficiency, and The present invention relates to a color moving image decoding method.

For example, in the conventional color moving image encoding device described in Non-Patent Document 1 below, an input color image is divided into maximum encoding blocks of a predetermined size, and the maximum encoding block is further divided. Hierarchy is divided into fine coding blocks.
Further, the encoded block is divided into finer prediction blocks, and prediction errors are generated by performing intra prediction and motion compensation prediction on the prediction block.
Further, the prediction error is hierarchically divided into transform blocks in the coding block, and each transform coefficient is entropy coded to achieve a high compression rate.

  For the transform block, when the prediction block is a rectangle of 2N × N size or 2N × 0.5N size, the long side and the short side have a length of 2N × 0.5N as shown in FIG. By dividing the transform block hierarchically into a quadtree like a non-square transform block, the transform block does not cross the boundary of the prediction block, and entropy coding of the transform coefficient is performed in N × N size. A high compression ratio is achieved by compressing by means common to the square transform block.

  In the conventional color moving image encoding apparatus, when encoding a YUV 4: 2: 0 signal, the size of the prediction block and the conversion block of the color difference signal is fixed to the vertical and horizontal half size of the conversion block size of the luminance signal. Therefore, it is not necessary to encode information related to the transform block size of the color difference signal, and the color difference signal can be reduced with a small circuit scale by compressing the entropy coding of the transform coefficient with the transform coefficient entropy encoding means common to the luminance signal. Enhancing encoding efficiency.

B. Bross, W.-J. Han, J.-R. Ohm, GJ Sullivan, Y.-K. Wang and T. Wiegand, "High Efficiency Video Coding (HEVC) text specification draft 10 (for FDIS & Consent) ", Doc. JCTVC-L1003, Joint Collaborative Team on Video Coding (JCT-VC) of ITU-T SG16 WP3 and ISO / IEC JTC1 / SC29 / WG11, 12th Meeting, 2013

  Since the conventional color moving image encoding apparatus is configured as described above, when encoding the YUV 4: 2: 0 signal, the entropy encoding unit of the color difference signal conversion block is used as the entropy encoding unit of the luminance signal. Can be shared with. Therefore, the color difference signal can be efficiently encoded with a small circuit scale. However, when encoding a YUV 4: 2: 2 signal or a YUV 4: 4: 4 signal, the shape of the color difference signal is YUV 4: 2: 0. Since the shape of the color difference signal of the signal is different, an additional circuit scale is required to support encoding of signals including more color components than YUV 4: 2: 2 signal, YUV 4: 4: 4 signal, RGB signal, and three primary colors. There was a problem that would increase.

The present invention has been made to solve the above-described problems. Even when encoding a YUV 4: 4: 4 signal, an RGB signal, or a signal including more color components than three primary colors, the circuit scale can be reduced. It is an object of the present invention to obtain a color moving image encoding apparatus and a color moving image encoding method capable of improving the encoding efficiency of luminance signals and color difference signals or respective color components while keeping the size small.
It is another object of the present invention to obtain a color moving image decoding apparatus and a color moving image decoding method capable of accurately decoding a moving image from encoded data whose encoding efficiency is improved.

  In the color moving image encoding device according to the present invention, the predicted image generation unit has the same color component as the color component to be decoded included in another decoded picture for color components other than the first color component. A predicted image is generated by performing inter-frame predictive decoding using the decoded image as a reference image, or pixels of the decoded image of the first color component included in the same decoded picture and the first to be decoded By performing inter-frame predictive decoding using a correlation parameter representing a correlation with a pixel to be decoded of a color component other than a color component and the decoded image of the first color component, the first to be decoded The predicted image of the color component other than the color component is generated.

  According to the present invention, for the color components other than the first color component, the predicted image generation unit uses a decoded image having the same color component as the color component to be decoded included in another decoded picture as a reference image. A prediction image is generated by performing inter-frame prediction decoding, or a color component other than the first color component to be decoded and the pixel of the decoded image of the first color component included in the same decoded picture A color other than the first color component to be decoded by performing inter-frame predictive decoding using a correlation parameter representing a correlation with a decoding target pixel and the decoded image of the first color component Since the prediction image of the component is generated, even when encoding a signal including a YUV 4: 4: 4 signal, an RGB signal, or a signal including more color components than the three primary colors, the luminance is reduced while keeping the circuit scale small. Signal and color difference signal Rui has the advantage of being able to improve the coding efficiency of each color component.

It is a block diagram which shows the color moving image encoding device by Embodiment 1 of this invention. It is a flowchart which shows the processing content of the color moving image encoder by Embodiment 1 of this invention. It is a block diagram which shows the variable length encoding part 13 of the color moving image encoding device by Embodiment 1 of this invention. It is a block diagram which shows the color moving image decoding apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing content of the color moving image decoding apparatus by Embodiment 1 of this invention. It is a block diagram which shows the variable length decoding part 41 of the color 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 explanatory drawing which shows the conversion block size at the time of implementing the compression process of the luminance signal and color-difference signal in the signal of 4: 2: 0 format. It is explanatory drawing which shows the conversion block size at the time of implementing the compression process of the luminance signal and color-difference signal in the signal of 4: 2: 2 format and 4: 4: 4 format. It is explanatory drawing which shows the scan order of a 4x4 orthogonal transformation coefficient. It is explanatory drawing which shows the reverse scan order of a 4x4 orthogonal transformation coefficient. It is explanatory drawing which shows the context index value predetermined according to the frequency position. It is explanatory drawing which shows the context index value predetermined according to the frequency position. It is a block diagram which shows the color moving image encoding device by Embodiment 2, 3, 4 of this invention. It is a block diagram which shows the correlation utilization estimation part 61 of the color moving image encoder by Embodiment 2, 3, 4 of this invention. It is explanatory drawing which shows the local decoding image utilized as a reference image. It is an explanatory diagram showing a reference pixel Rec _C between reference pixels Rec _'L and the screen display. It is a block diagram which shows the color moving image decoding apparatus by Embodiment 2, 3, 4 of this invention. It is a block diagram which shows the correlation utilization estimation part 71 of the color moving image decoding apparatus by Embodiment 2, 3, 4 of this invention. It is a block diagram which shows the color moving image encoding device by Embodiment 2, 3, 4 of this invention. It is a block diagram which shows the correlation utilization adaptive prediction part 81 of the color moving image encoder by Embodiment 2, 3, 4 of this invention. It is a block diagram which shows the color moving image decoding apparatus by Embodiment 2, 3, 4 of this invention. It is a block diagram which shows the correlation utilization adaptive prediction part 91 of the color moving image decoding apparatus by Embodiment 2, 3, 4 of this invention. It is an explanatory diagram showing a pixel Rec _C of the pixel Rec _'L and the encoding target block in the reference block. It is explanatory drawing which shows the example which classified the pixel in a reference block into the class. It is a block diagram which shows the color moving image encoding device by Embodiment 4 of this invention. It is a block diagram which shows the inter prediction part 101 of the color moving image encoder by Embodiment 4 of this invention. It is explanatory drawing which shows the local decoding image utilized as a reference image. It is explanatory drawing which shows the pixel position of spatially adjacent PU among PU registered into a merge candidate list. It is explanatory drawing which shows that the inter prediction parameter reference image is selected from the reference images of a 1st color component. It is explanatory drawing which shows the determination procedure of merge candidate PU on the inter prediction parameter reference image in the case of the 2nd or 3rd color component. Explanatory drawing which produces | generates an interpolation pixel from an adjacent pixel, and makes it a predicted value It is a block diagram which shows the color moving image decoding apparatus by Embodiment 4 of this invention. It is a block diagram which shows the inter estimation part 111 of the color moving image decoding apparatus by Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a block diagram showing a color moving image encoding apparatus according to Embodiment 1 of the present invention.
The video signal to be processed by the color moving image encoding apparatus according to the first embodiment is 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 a color video signal, the video frame is an arbitrary video signal such as a monochrome image signal or an infrared image signal, in which a video frame is composed of a horizontal / 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, unless otherwise specified, the input video signal is YUV4: 2 in which the two color difference components U and V are subsampled in half both vertically and horizontally with respect to the luminance component Y: 0 format, YUV4: 2: 2 format in which two color difference components U and V are subsampled in half in the horizontal direction with respect to luminance component Y, or two color difference components U and V are luminance component Y And 4: 4: 4 format (for example, YUV4: 4: 4, RGB, etc.).
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.

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 transform block division flag indicating the quantization parameter and the transform block size is included in the prediction difference coding parameter and is output to the transform / quantization unit 7, the inverse quantization / inverse transform unit 8, the variable length coding unit 13, and the like. Is done.
The encoding control unit 1 constitutes an encoding control unit.

Here, FIG. 13 is an explanatory diagram showing a conversion block size when performing compression processing (conversion processing, quantization processing) of luminance signals and color difference signals in a 4: 2: 0 format signal.
As shown in FIG. 13, the transform block size is determined by hierarchically dividing the encoded block into a quadtree.
For example, whether or not to divide the transform block so that the evaluation value is minimized based on the amount of code when the transform block is divided and when the transform block is not divided, the evaluation scale that takes into account the coding error, etc. By determining, it is possible to determine the optimal division shape of the transform block from the viewpoint of the trade-off between the code amount and the coding error.

For the luminance signal, for example, as illustrated in FIG. 13, when the prediction mode in which the shape of the prediction block of the luminance signal is a square is selected as the encoding mode of the encoding block, one or more encoding blocks are included. It is configured to be hierarchically divided into square transform blocks.
On the other hand, when the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is selected as the coding mode of the coding block, the coding block is hierarchically divided into one or a plurality of rectangular transform blocks. Configure.

As for the color difference signal, as shown in FIG. 13, when the input signal format is a YUV 4: 2: 0 signal, the prediction mode in which the shape of the prediction block of the luminance signal is a square is the encoding mode of the encoding block. If selected, the coding block is configured to be hierarchically divided into one or a plurality of square transform blocks in the same manner as the luminance signal. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.
On the other hand, if the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is selected as the encoding mode of the encoding block, the encoding block is converted into one or a plurality of rectangular transform blocks, similarly to the luminance signal. It is configured to be divided hierarchically. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.

As shown in FIG. 14, when the input signal format is a YUV 4: 2: 2 signal, the coding block has one or more squares for the color difference signal regardless of the shape of the prediction block of the luminance signal. It is configured to be divided hierarchically into transform blocks. In this case, the color difference signal conversion block shape is always a rectangle in which the number of pixels in the vertical direction is twice the number of pixels in the horizontal direction.
Also, as shown in FIG. 14, when the input signal format is 4: 4: 4 signal, the color difference signal conversion block always performs the same division as the luminance signal conversion block, and the same size conversion block. To be configured.
The division information of the transformation block of the luminance signal is output to the variable length coding unit 13 as a transformation block division flag indicating whether or not to divide for each layer.

When a color image signal indicating an input color image (current picture) is input, the block dividing unit 2 divides the input color image into encoded blocks of the maximum size determined by the encoding control unit 1, and the encoding control unit The process of dividing the encoded block hierarchically is performed until the upper limit number of hierarchies determined by 1 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, the chrominance component in the coding block divided by the block dividing unit 2 is selected by the coding control unit 1 when the input signal format is YUV4: 2: 0 signal or YUV4: 2: 2 signal. If the coding mode is the luminance / chrominance common intra prediction mode indicating that the same intra prediction mode as that of the luminance signal is applied, the luminance signal and the luminance signal are compared with the color difference component in the coding block divided by the block dividing unit 2. Intraframe prediction is performed in the same intra prediction mode to generate a prediction image for the color difference component.

If the coding mode selected by the coding control unit 1 is the directional prediction mode in the intra coding mode, the directional frame is applied to the color difference component in the coding block divided by the block dividing unit 2. Intra prediction is performed to generate a prediction image for the color difference component.
Also, if the coding mode selected by the coding control unit 1 is the luminance correlation-use color difference signal prediction mode in the intra coding mode, the horizontal direction and the vertical direction among the pixels constituting the coding block Is used to calculate a correlation parameter indicating the correlation between the luminance component and the color difference component, and the luminance component corresponding to the color difference component coding block to be processed is calculated. The prediction image for the color difference component is generated.

When the input signal format is 4: 4: 4 signal, the process of the luminance color difference common intra prediction mode or the luminance correlation using color difference signal prediction mode is performed, and the directionality prediction mode is not selected. Also good.
In the 4: 4: 4 signal, the edge positions between the color components have a high correlation, and therefore, a directionality prediction mode different from the first color component corresponding to the YUV luminance signal is applied to the other color component signals. By prohibiting, it is possible to reduce the amount of information in the intra prediction mode of other color component signals and increase the coding efficiency.
Needless to say, the direction prediction mode different from the luminance signal may be selected for the other color component signals.

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.
Note that a prediction image generation unit is configured by the changeover switch 3, the intra prediction unit 4, and the motion compensation prediction unit 5.

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 converts the difference image generated by the subtraction unit 6 in units of transform block size specified from the transform block division flag included in the prediction difference encoding parameter output from the encoding control unit 1. Performing transform processing (for example, DCT (discrete 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 prediction differential code Using the quantization parameter included in the quantization parameter, the transform coefficient of the difference image is quantized to output the quantized transform coefficient as compressed data of the difference image.

That is, when the transform / quantization unit 7 performs transform / quantization processing (compression processing) on the difference image of the encoded block generated by the subtraction unit 6, the luminance signal is, for example, as shown in FIG. If the prediction mode in which the shape of the prediction block of the luminance signal is square is selected as the coding mode of the coding block, the coding block is hierarchically divided into one or a plurality of square transform blocks. Configure.
On the other hand, if the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is selected as the encoding mode of the encoding block, the encoding block is hierarchically divided into one or a plurality of rectangular transform blocks. Configure as follows.

As for the color difference signal, as shown in FIG. 13, when the input signal format is a YUV 4: 2: 0 signal, the prediction mode in which the shape of the prediction block of the luminance signal is a square is the encoding mode of the encoding block. If selected, the coding block is configured to be hierarchically divided into one or a plurality of square transform blocks in the same manner as the luminance signal. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.
On the other hand, if the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is selected as the encoding mode of the encoding block, the encoding block is converted into one or a plurality of rectangular transform blocks, similarly to the luminance signal. It is configured to be divided hierarchically. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.

When the input signal format is a YUV 4: 2: 2 signal, the coding block is divided hierarchically into one or a plurality of square transform blocks for the color difference signal regardless of the shape of the prediction block of the luminance signal. To be configured. In this case, the color difference signal conversion block shape is always a rectangle in which the number of pixels in the vertical direction is twice the number of pixels in the horizontal direction.
When the input signal format is a YUV 4: 4: 4 signal, the color difference signal conversion block is always divided in the same manner as the luminance signal conversion block so as to be the same size conversion block.
The transform / quantization unit 7 performs difference image transform / quantization processing on a block basis after division by the block division unit 2.
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)) in units of transform block size specified from the transform block division flag included in the prediction difference encoding parameter By performing inverse DST (inverse discrete sine transform), inverse KL transform, or the like), a 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 coding unit 13 includes input signal format information for specifying an input signal format, compressed data output from the transform / quantization unit 7, a coding mode output from the coding control unit 1, and a transform block division flag. And the prediction prediction encoding parameter including the intra prediction parameter output from the intra prediction unit 4 or the inter prediction parameter output from the motion compensated prediction unit 5 and the motion information are variable-length encoded by arithmetic encoding, and the input A process of generating a bit stream in which encoded data such as signal format information, compressed data, encoding mode, prediction differential encoding parameter, intra prediction parameter / inter prediction parameter, and motion information is multiplexed is performed.

That is, when the variable length coding unit 13 performs variable length coding on the transform coefficient that is the compressed data output from the transform / quantization unit 7, if the signal format of the input color image is YUV 4: 2: 0, the difference Referring to the context value information for YUV 4: 2: 0 in which the context value of each conversion coefficient in the color difference signal of the image is assigned according to the frequency position of the conversion coefficient, the context value of each conversion coefficient in the color difference signal Is specified, and each conversion coefficient in the color difference signal is arithmetically encoded using the occurrence probability corresponding to the context value of the conversion coefficient.
When the signal format of the input color image is YUV4: 2: 2, each conversion coefficient in the color difference signal when the signal format is YUV4: 2: 0 is used as the context value of each conversion coefficient in the color difference signal of the input color image. Referring to the context value information for YUV 4: 2: 2 in which two context values identical to the context value are repeatedly assigned in the vertical direction of the frequency position, the context value of each conversion coefficient in the color difference signal is specified Then, using the occurrence probability corresponding to the context value of the transform coefficient, each transform coefficient in the color difference signal is arithmetically encoded.
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, a transform / quantization unit, which are components of the color moving image coding apparatus. 7, each of the inverse quantization / inverse transform unit 8, the adder 9, the intra prediction memory 10, the loop filter unit 11, the motion compensated prediction frame memory 12, and the variable length coding unit 13 includes dedicated hardware (e.g., CPU However, the color moving image encoding device may be configured by a computer or the like.
When the color moving image encoding apparatus is configured by a computer, the intra prediction memory 10 and the motion compensated prediction frame memory 12 are configured on the memory of the computer, and the encoding control unit 1, the block division unit 2, and the changeover switch 3 are configured. , Intra Prediction Unit 4, Motion Compensation Prediction Unit 5, Subtraction Unit 6, Transformation / Quantization Unit 7, Inverse Quantization / Inverse Transformation Unit 8, Addition Unit 9, Loop Filter Unit 11, and Variable Length Encoding Unit 13 May be stored in the memory of the computer, and the CPU of the computer may execute the program stored in the memory.
FIG. 2 is a flowchart showing the processing contents of the color moving image coding apparatus according to Embodiment 1 of the present invention.

Here, FIG. 3 is a block diagram showing the variable length coding unit 13 of the color moving image coding apparatus according to Embodiment 1 of the present invention.
In FIG. 3, the transform coefficient variable length coding unit 21 performs a process of variable length coding the orthogonal transform coefficient that is the compressed data output from the transform / quantization unit 7.
The encoding parameter variable length encoding unit 22 includes input signal format information, a prediction differential encoding parameter including the encoding mode and transform block division flag output from the encoding control unit 1, and intra prediction output from the intra prediction unit 4. A process of performing variable-length coding on encoding parameters such as inter prediction parameters and motion information output from the parameter or motion compensation prediction unit 5 and block division information indicating the division status of the encoded block is performed.
The encoded data of the compressed data variable-length encoded by the transform coefficient variable-length encoding unit 21 and the encoding parameter variable-length encoded by the encoding parameter variable-length encoding unit 22 are multiplexed to form a bit stream Is generated.

FIG. 4 is a block diagram showing a color moving image decoding apparatus according to Embodiment 1 of the present invention.
In FIG. 4, the variable length decoding unit 41 is a code that is hierarchically divided from the maximum size of a coding block that is a processing unit when intra prediction processing or motion compensation prediction processing is performed, and a 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. From each encoded data, the compressed data related to the encoded block, the input signal format information, the encoding mode, the prediction differential encoding parameter including the transform block division flag, the intra prediction parameter / inter prediction parameter, the motion information, and the like are variable. Perform long decoding and output the compressed data and the prediction differential encoding parameter to the inverse quantization / inverse transform unit 45 Rutotomoni, carries out a process of outputting the encoding mode and the intra prediction parameters / inter prediction parameter to the changeover switch 42.

That is, when the variable length decoding unit 41 performs variable length decoding of the transform coefficient, which is compressed data related to the encoded block, from each encoded data, when the signal format indicated by the input signal format information is YUV 4: 2: 0, Referring to the context value information for YUV 4: 2: 0 in which the context value of each conversion coefficient in the color difference signal of the difference image is assigned according to the frequency position of the conversion coefficient, the context of each conversion coefficient in the color difference signal A value is specified, and each transform coefficient in the color difference signal is arithmetically decoded using an occurrence probability corresponding to the context value of the transform coefficient.
When the signal format indicated by the input format information is YUV 4: 2: 2, each conversion coefficient in the color difference signal when the signal format is YUV 4: 2: 0 is used as the context value of each conversion coefficient in the color difference signal of the input color image. Referring to the context value information for YUV 4: 2: 2 in which the same context value is repeatedly assigned in the vertical direction of the frequency position, the context value of each conversion coefficient in the color difference signal is determined. Using the occurrence probability corresponding to the context value of the transform coefficient, the transform coefficient in the color difference signal is arithmetically decoded.
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, the intra prediction unit 43 performs intra-frame prediction of the luminance component, and generates a predicted image for the luminance component.
On the other hand, for the color difference component in the coding block, when the input signal format is YUV4: 2: 0 signal or YUV4: 2: 2 signal, the coding mode variable-length decoded by the variable-length decoding unit 41 is In the case of the luminance / chrominance common intra prediction mode indicating that the same intra prediction mode as that of the luminance signal is applied, intra-frame prediction is performed on the chrominance component in the coding block using the same intra prediction mode as that of the luminance signal, and the color difference is determined. Generate a predicted image for the component.

In addition, if the coding mode that has been variable-length decoded by the variable-length decoding unit 41 is the directional prediction mode in the intra coding mode, the directional intra-frame prediction is performed on the color difference component in the coding block. The prediction image for the color difference component is generated.
Further, if the encoding mode variable-length decoded by the variable-length decoding unit 41 is the luminance correlation-use color difference signal prediction mode in the intra encoding mode, among the pixels constituting the encoding block, the horizontal direction and Using the luminance components of a plurality of pixels adjacent in the vertical direction, a correlation parameter indicating the correlation between the luminance component and the color difference component is calculated, and the luminance corresponding to the correlation parameter and the color difference component coding block to be processed A predicted image for the color difference component is generated using the component.

When the input signal format is 4: 4: 4 signal, the process of the luminance color difference common intra prediction mode or the luminance correlation using color difference signal prediction mode is performed, and the directionality prediction mode is not selected. Also good.
In the YUV 4: 4: 4 signal, there is a high correlation between the edge positions of the luminance signal and the color difference signal. It is possible to increase the coding efficiency by reducing the amount of information in the prediction mode.
Naturally, a direction prediction mode different from the luminance signal may be selected for the color difference signal.

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 Inverse transform processing (for example, inverse DCT (inverse discrete cosine) of compressed data of inverse quantization in units of transform block size specified from the transform block division flag included in the prediction differential encoding parameter. Conversion), inverse DST (inverse discrete sine transform), inverse KL transformation, etc.), and the compressed data after the inverse transformation process is used as a decoded prediction difference signal (a signal indicating a difference image before compression). Perform the output process.
That is, the inverse quantization / inverse transform unit 45 converts the transform block shape of the luminance signal divided hierarchically based on the transform block partition flag included in the prediction difference encoding parameter output from the variable length decoding unit 41. Identify and perform inverse quantization and inverse transform on a transform block basis.

Specifically, for the luminance signal, when the prediction mode in which the shape of the prediction block of the luminance signal is a square is the encoding mode of the encoding block, one encoding block is determined based on the transform block division flag or It is configured so as to be hierarchically divided into a plurality of square transform blocks.
On the other hand, when the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is the encoding mode of the encoding block, the encoding block is hierarchically divided into one or a plurality of rectangular transform blocks. To do.

For the color difference signal, when the input signal format is a YUV 4: 2: 0 signal, if the prediction mode in which the shape of the prediction block of the luminance signal is a square is the encoding mode of the encoding block, the same as the luminance signal In addition, the encoding block is configured to be hierarchically divided into one or a plurality of square transform blocks. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.
On the other hand, if the prediction mode in which the prediction block of the luminance signal is rectangular is the encoding mode of the encoding block, the encoding block is hierarchically divided into one or a plurality of rectangular transform blocks as in the luminance signal. Configure to be split. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.

When the input signal format is a YUV 4: 2: 2 signal, the coding block is divided hierarchically into one or a plurality of square transform blocks for the color difference signal regardless of the shape of the prediction block of the luminance signal. To be configured. In this case, the conversion block shape of the color difference signal is always a rectangle in which the number of pixels in the vertical direction is twice the number of pixels in the horizontal direction.
When the input signal format is a YUV 4: 4: 4 signal, the color difference signal conversion block is always divided in the same manner as the luminance signal conversion block so as to be the same size conversion block.
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. 4, 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 an intra prediction component that are components of the color moving image decoding apparatus. Each of the memory 47, the loop filter unit 48, and the motion compensation prediction frame memory 49 is configured by dedicated hardware (for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or a memory). Assuming, the color moving image decoding apparatus may be configured by a computer or the like.
When the color moving image decoding apparatus is configured by a computer, the intra prediction memory 47 and the motion compensated prediction frame memory 49 are configured on the memory of the computer, and the variable length decoding unit 41, the changeover switch 42, the intra prediction unit 43, All or part of the program describing the processing contents of the motion compensation unit 44, the inverse quantization / inverse conversion unit 45, the addition unit 46, and the loop filter unit 48 is stored in the memory of the computer, and the CPU of the computer The program stored in the memory may be executed.
FIG. 5 is a flowchart showing the processing contents of the color moving image decoding apparatus according to Embodiment 1 of the present invention.

FIG. 6 is a block diagram showing the variable length decoding unit 41 of the color moving image decoding apparatus according to Embodiment 1 of the present invention.
In FIG. 6, a transform coefficient variable length decoding unit 51 performs a process of variable length decoding orthogonal transform coefficients that are compressed data from encoded data multiplexed in a bit stream.
The encoding parameter variable length decoding unit 52 receives input signal format information, encoding mode, prediction differential encoding parameter, intra prediction parameter / inter prediction parameter, motion information, block division information, etc. from the encoded data multiplexed in the bitstream. A process for variable-length decoding of the coding parameters is performed.

Next, the operation will be described.
First, the processing contents of the color moving image 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 coding block of the maximum size is divided hierarchically 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.
Also, the difference in the complexity of the local motion of the input color 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. Possible methods.
The upper limit of the number of hierarchies is set so that, for example, the more intense the input color image moves, the deeper the number of hierarchies, so that more detailed movement can be detected. The method of setting to can be 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 color image is input, the block dividing unit 2 divides the input color image into encoded blocks of the maximum size determined by the encoding control unit 1 and is determined by the encoding control unit 1. The encoded block is divided hierarchically until the upper limit number of layers is reached. Further, the encoded block is divided into partitions (step ST3).
Here, FIG. 7 is an explanatory diagram showing a state in which a maximum-size encoded block is hierarchically divided into a plurality of encoded blocks.
In the example of FIG. 7, the maximum size encoded block is the 0th layer encoded block B ⁰ , and has a size of (L ⁰ , M ⁰ ) as a luminance component.
In the example of FIG. 7, the encoding block B ⁿ is obtained by performing hierarchical division to a predetermined depth determined separately in a quadtree structure with the encoding block B ⁰ having the maximum size as a starting point. 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. 7 shows a 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, an encoding mode that can be selected in the encoding 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”), one or more inter coding modes (collectively “INTER”), As described above, the encoding control unit 1 selects an encoding mode having 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. 7, the coding block B ⁿ is further divided into one or more prediction processing units (partitions).
Hereinafter, the partition belonging to the coding block B ⁿ is ^denoted as P _i ⁿ (i: the partition number in the nth layer). FIG. 8 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 coding 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. 9 for the encoding block of the maximum size, and specifies the encoding block ^Bn .
9A shows the distribution of the partitions after the division, and FIG. 9B shows a situation where the encoding mode m (B ⁿ ) is assigned to the partition after the hierarchical division in a quadtree graph. Show.
In FIG. 9B, nodes surrounded by squares indicate nodes (encoded blocks B ⁿ ) to which the encoding mode m (B ⁿ ) is assigned.
Also, the encoding control unit 1 determines the division shape of the transform block as described above for the divided partition.

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 ) εINTER), the partition P _i ⁿ belonging to the coding block B ⁿ is output to the motion compensation prediction unit 5. .

When receiving the partition P _i ⁿ belonging to the coding block B ⁿ from the changeover switch 3 (step ST4), the intra prediction unit 4 receives each partition P _i ⁿ based on the intra prediction parameters determined by the coding control unit 1. Intra prediction image (P _i ⁿ ) is generated by performing intra prediction processing on (step ST5).
Hereinafter, in this specification, P _i ⁿ indicates a partition, and (P _i ⁿ ) indicates a predicted image of the partition P _i ⁿ .

Since the intra prediction parameters used to generate the intra-prediction image (P i ^_n) is also a color video decoding apparatus side, it is necessary to generate exactly the same intra prediction image (P i ^_n), the variable length coding unit 13 Is multiplexed into the 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.

Here, the processing content of the intra estimation part 4 is demonstrated concretely.
FIG. 10 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. 10, the prediction direction vector corresponding to the intra prediction mode is shown, and the relative angle between the prediction direction vectors is designed to decrease as the number of selectable intra prediction modes increases.

First, 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.
Follows is a description of the process of generating the predicted image for the luminance component, here, the intra prediction unit 4, based on the intra prediction parameters (intra prediction mode) for the luminance signal partitions P _i ^n, that the luminance signal Intra processing for generating the intra prediction signal will be described.
For convenience of explanation, the size of the partition _P ^{i n} a _l ^{i n} × _m ^{i n} pixels.

FIG. 11 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. 11, the partition _P ^{i n} in the pixel on the partition already coded that is adjacent to ^{_{((2 × l i n +1}} ) pixels), the left partition pixel ((2 × _m ⁱ n) The number of pixels) is a reference pixel used 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. 11, 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 intra prediction mode index value for the partition P _i ⁿ is 2 (average value prediction), the intra prediction unit 4 calculates the average value of the adjacent pixels in the upper partition and the adjacent pixels in the left partition in the partition P _i ⁿ . A predicted image is generated as a predicted value of the pixel.
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.
Partitioning P _i ⁿ in the relative coordinates of the pixels for generating the prediction value (prediction target pixel) a (an origin at the upper left pixel of the partition) as (x, y), the position of the reference pixels used for prediction, the following 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. 11, since the reference pixel is not located at the integer pixel position, an 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 intra prediction unit 4 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 encoding unit 13 for multiplexing into the bitstream.

  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.

Here, although the intra-frame prediction of the luminance component in the coding block is performed to generate a predicted image for the luminance component, the predicted image for the color difference component is generated as follows.
FIG. 12 is an explanatory diagram showing an example of correspondence between intra prediction parameters of color difference signals and color difference intra prediction modes.
When the input signal format is YUV4: 2: 0 signal or YUV4: 2: 2 signal, it indicates that the encoding mode selected by the encoding control unit 1 applies the same intra prediction mode as the luminance signal. In the case of the luminance / chrominance common intra prediction mode, intra-frame prediction is performed on the chrominance component in the encoded block divided by the block dividing unit 2 in the same intra prediction mode as the luminance signal, and a prediction image for the chrominance component is obtained. Generate.

If the coding mode selected by the coding control unit 1 is the directional prediction mode in the intra coding mode, the directional intra-frame prediction is performed on the color difference component in the coding block divided by the block dividing unit 2. To generate a predicted image for the color difference component.
Also, if the coding mode selected by the coding control unit 1 is the luminance correlation-use color difference signal prediction mode in the intra coding mode, the horizontal direction and the vertical direction among the pixels constituting the coding block Is used to calculate a correlation parameter indicating the correlation between the luminance component and the color difference component, and the luminance component corresponding to the color difference component coding block to be processed is calculated. The prediction image for the color difference component is generated.

When the input signal format is a YUV 4: 4: 4 signal, the processing of the luminance color difference common intra prediction mode or the luminance correlation using color difference signal prediction mode is performed, and the directionality prediction mode is not selected. Also good.
In the YUV 4: 4: 4 signal, there is a high correlation between the edge positions of the luminance signal and the color difference signal. It is possible to increase the coding efficiency by reducing the amount of information in the prediction mode.
Naturally, a direction prediction mode different from the luminance signal may be selected for the color difference signal.

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. ^The inter prediction image (P _i ⁿ ) is generated by performing the inter prediction process for ⁿ (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.
For inter prediction parameters to be used in generating the inter prediction image (P i ^_n) is also a color video decoding apparatus side, it is necessary to generate exactly the same inter-prediction image (P i ^_n), the variable length coding unit 13 Is multiplexed into the bitstream.

When the subtraction unit 6 receives the predicted image (P _i ⁿ ) from the intra prediction unit 4 or the motion compensation prediction unit 5, the subtraction unit 6 performs 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).

Transform and quantization unit 7, the subtraction unit 6 generates a prediction difference signal e _i ^n, the transformation block size determined by the coding control unit 1, the conversion processing for the prediction difference signal e _i ⁿ (e.g., DCT (Discrete Cosine Transform), DST (Discrete Sine Transform), and orthogonal transform processing such as KL transform in which a base design is made in advance for a specific learning sequence) are included in the prediction differential encoding parameters. By quantizing the transform coefficient of the prediction difference signal e _i ⁿ using the quantized parameter, the compressed image of the differential image, which is the transform coefficient after quantization, is converted into the inverse quantization / inverse transform unit 8 and the variable It outputs to the long encoding part 13 (step ST8).
That is, when the subtraction unit 6 generates the prediction difference signal e _i ⁿ , the transform / quantization unit 7 performs division / quantization processing on the luminance signal of the prediction difference signal e _i ⁿ by the block division unit 2. The encoded block is further divided hierarchically, and luminance signal conversion / quantization processing is performed in units of the divided blocks.
That is, when the prediction mode in which the shape of the prediction block of the luminance signal is square is selected as the encoding mode of the encoding block, the encoding block is hierarchically divided into one or a plurality of square transform blocks. Configure.
On the other hand, when the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is selected as the coding mode of the coding block, the coding block is hierarchically divided into one or a plurality of rectangular transform blocks. Configure.

As for the color difference signal, as shown in FIG. 13, when the input signal format is a YUV 4: 2: 0 signal, the prediction mode in which the shape of the prediction block of the luminance signal is a square is the encoding mode of the encoding block. If selected, the coding block is configured to be hierarchically divided into one or a plurality of square transform blocks in the same manner as the luminance signal. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.
On the other hand, if the prediction mode in which the shape of the prediction block of the luminance signal is rectangular is selected as the encoding mode of the encoding block, the encoding block is converted into one or a plurality of rectangular transform blocks, similarly to the luminance signal. It is configured to be divided hierarchically. In this case, the conversion block size of the color difference signal is half the vertical and horizontal sizes of the corresponding luminance signal conversion block.

As shown in FIG. 14, when the input signal format is a YUV 4: 2: 2 signal, the coding block has one or more squares for the color difference signal regardless of the shape of the prediction block of the luminance signal. It is configured to be divided hierarchically into transform blocks. In this case, the color difference signal conversion block shape is always a rectangle in which the number of pixels in the vertical direction is twice the number of pixels in the horizontal direction.
As shown in FIG. 14, when the input signal format is a YUV 4: 4: 4 signal, the color difference signal conversion block always performs the same division as the luminance signal conversion block, and the same size conversion block. To be configured.

  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 inverse transform processing (for example, inverse DCT (inverse discrete) of the quantized compressed data is performed in transform block size units specified from the transform block division flag included in the prediction differential encoding parameter. By performing (cosine transform), inverse DST (discrete sine transform), inverse KL transform, etc.), the compressed data after the inverse transform is output to the adder 9 as a local decoded prediction difference signal (step ST9). ).

Upon receiving the local decoded prediction difference signal from the inverse quantization / inverse transform unit 8, the adder 9 receives the local decoded prediction difference signal and the predicted image (P _i ) generated by the intra prediction unit 4 or the motion compensated 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 “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).
Here, since the coding distortion occurs along the boundary of the transform block, the coding distortion is compensated for the boundary of the transform block. For small transform blocks, the coding distortion at the transform block boundary is inconspicuous, so signal the minimum loop filter application block size in the header and code only for blocks whose transform block size is larger than the minimum loop filter application block size. It may be configured to apply the distorted distortion compensation. In this way, since unnecessary encoding distortion compensation can be omitted, the amount of calculation can be reduced while maintaining the image quality.

It is also known that coding distortion occurs as an offset of a pixel value near the edge of an image or in a flat portion.
For such coding distortion, for each predetermined block, the edge direction of the locally decoded image, the distribution of pixel values, and the like are analyzed, and the adaptive pixel offset type, which is the edge direction or pixel value level information, is determined. At the same time, for each edge type and sub-level of the pixel value in the block, a pixel offset value that compensates for coding distortion generated as a pixel value offset is determined, and the pixel offset value is added to the locally decoded image. May be configured to compensate for encoding distortion.
In this case, the adaptive pixel offset type and the pixel offset value are variable-length encoded by the variable-length encoding unit 13.

Here, when the input signal is in the 4: 4: 4 format, there is a high possibility that the edge portion is common to each color component. Therefore, in the block, the pixel offset of the edge portion is compensated, or the other portion. The texture type indicating whether to compensate for the pixel offset is determined, and the texture type information indicating the texture type is variable length encoded by the variable length encoding unit 13.
If the texture type indicates an edge portion, determine a common edge direction for all color components (for example, the edge direction with the highest coding efficiency among all color components is the same for all color components) Edge direction information indicating the edge direction is variable-length encoded by the variable-length encoding unit 13, and a common edge type is determined for all color components, and each color is determined for each edge type. The pixel offset value is determined independently of the component (for example, the pixel offset value is determined by referring to a table that records the pixel offset value corresponding to the edge type), and the pixel offset value is variable-length encoded. The unit 13 performs variable length coding.

On the other hand, when the texture type indicates that it is not an edge portion, the pixel value level is determined independently for each color component (for example, when the pixel value is in the range of 0 to 255, four levels (level 1 (0 -63), level 2 (64-127), level 3 (128-191), and level 4 (192-255) are defined, and if the pixel value is "102", the level 2 is determined. If the pixel value is “185”, the level is determined to be level 3), and the variable length encoding unit 13 performs variable length encoding on the level information indicating the level.
Further, the pixel offset value is determined for each sub-level of the pixel value in the block independently for each color component (for example, the level of the pixel value is further classified into sub-levels (for example, 16 levels), and the sub-levels are determined. The pixel offset value is determined with reference to a table in which the pixel offset value corresponding to is recorded), and the variable length encoding unit 13 performs variable length encoding on the pixel offset value.

  In this way, since information common to all color components is variable-length encoded for the edge portion, the edge portion information can be signaled with a small amount of information. On the other hand, information different for each color component is determined independently and subjected to variable length coding, so that the image distortion can be appropriately compensated for each color component to improve the image quality.

In addition, since the division shape of the transform block is different between the luminance signal and the color difference signal, the coding distortion compensation is configured to specify and process the division shape of the transformation block for each of the luminance signal and the color difference signal.
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.

Processing in step ST4~ST10 is repeatedly performed until the processing for the partitions _P ^{i n} that belong to all the coding blocks ^{B n} divided by the block dividing unit 2 is completed (step ST12).
The variable length coding unit 13 is a prediction difference coding parameter including input signal format information, compressed data output from the transform / quantization unit 7, a coding mode output from the coding control unit 1, and a transform block division flag. The intra-prediction parameter output from the intra-prediction unit 4 or the inter-prediction parameter and the motion information output from the motion-compensated prediction unit 5 are variable-length encoded, and the input signal format information, compressed data, encoding mode, and prediction A bit stream in which encoded data such as differential encoding parameters, intra prediction parameters / inter prediction parameters, and motion information is multiplexed is generated (step ST13).

  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.

Hereinafter, the processing content of the variable length encoding part 13 is demonstrated concretely.
As shown in FIG. 3, the variable length encoding unit 13 includes a transform coefficient variable length encoding unit 21 that performs variable length encoding on orthogonal transform coefficients that are compressed data output from the transform / quantization unit 7, and an input signal. Coding parameter variable length code for variable length coding of coding parameters such as format information, coding mode, prediction differential coding parameter including transform block division flag, intra prediction parameter / inter prediction parameter, motion information, block division information Encoding unit 22, encoded data of compressed data variable-length encoded by transform coefficient variable-length encoding unit 21, and code encoded by variable-length encoding by encoding parameter variable-length encoding unit 22 The bit stream is generated by multiplexing with the conversion parameter.

The transform coefficient variable length coding unit 21 of the variable length coding unit 13 uses the occurrence probability corresponding to the context value of the orthogonal transform coefficient that is the compressed data output from the transform / quantization unit 7, and uses the orthogonal transform coefficient. Is arithmetically encoded.
That is, the transform coefficient variable length encoding unit 21 arithmetically encodes a luminance component, a color difference component in YUV 4: 2: 0 format, or a color difference component in YUV 4: 4: 4 format as follows, and performs block coding data. Output as.

(1) Each orthogonal transform coefficient is scanned in the oblique scan order shown in FIG. 15, and the position of the nonzero orthogonal transform coefficient that is the last in the oblique scan order is specified as “PosLast”.
(2) Perform arithmetic coding of PosLastX which is a horizontal component of PosLast and PosLastY which is a vertical component of PosLast.
(3) The following processes (4) to (8) are performed from PosLast in the reverse oblique scan order (see FIG. 16) which is the reverse order to the oblique scan.

(4) Arbitrarily encode significant_coeff_flag indicating whether or not the orthogonal transform coefficient at the position of each frequency component is non-zero in reverse oblique scan order.
(5) Arithmetic coding of coeff_abs_level_greater1_flag indicating whether or not the absolute value of the orthogonal transform coefficient is greater than 1 for the orthogonal transform coefficient at the frequency component position indicating that significant_coeff_flag is non-zero in reverse diagonal scan order To do.
(6) Whether the absolute value of the orthogonal transform coefficient is greater than 2 for the orthogonal transform coefficient at the frequency component position where coeff_abs_level_greater1_flag indicates that the absolute value of the orthogonal transform coefficient is greater than 1 in reverse diagonal scan order Coeff_abs_level_greater2_flag indicating
(7) For the orthogonal transform coefficient at the frequency component position indicating that significant_coeff_flag is non-zero in reverse oblique scan order, coeff_sign_flag indicating the sign of the orthogonal transform coefficient is arithmetically encoded.
(8) For the orthogonal transform coefficient at the frequency component position where coeff_abs_level_greater2_flag indicates that the absolute value of the orthogonal transform coefficient is greater than 2 in the reverse oblique scan order, the value obtained by subtracting 3 from the absolute value of the orthogonal transform coefficient A certain coeff_abs_level_minus3 is arithmetically encoded.
(9) Repeat (3) until the last sub-block is reached.

For rectangular blocks with a transform block aspect ratio of 2N: 0.5N or 0.5N: 2N, orthogonal transform coefficients are mapped to N × N size blocks by performing the same oblique scan. A process similar to the above is performed later.
Here, as an occurrence probability used for arithmetic coding of significant_coeff_flag, if the pixel size is 4 × 4 or 8 × 8, for example, a context index value for YUV 4: 2: 0 as shown in FIG. Referring to the context value information), the context index value of each transform coefficient in the color difference signal is specified, and the occurrence probability corresponding to the context index value (for example, each region of the probability state memory not shown) In which occurrence probabilities corresponding to the context index values defined in the above are stored.

However, for the color difference signal when the input signal is in the YUV 4: 2: 2 format, since the shape of the conversion block is a rectangle that is twice as long as the width, the YUV 4: 2: as shown in FIG. Reference is made to the context index value for 2 (context value information).
For the context index value for YUV 4: 2: 2, the assignment of the context index value indicating the region of the probability state memory is repeatedly applied two by two in the vertical direction.
In this way, even when the input signal is in the YUV 4: 2: 2 format, the context index value assignment table of the color difference component in the YUV 4: 2: 0 format can be reused, and the compression efficiency can be reduced with a small circuit scale. Can be increased.

Next, processing contents of the color moving image decoding apparatus in FIG. 4 will be described.
When the variable length decoding unit 41 receives the bit stream generated by the color moving image encoding apparatus in FIG. 1, the variable length decoding unit 41 performs a variable length decoding process on the bit stream (step ST41 in FIG. 5), and more than one frame. The frame size is decoded in units of sequences composed of pictures or in units of pictures.
When the variable length decoding unit 41 decodes the frame size, it becomes the maximum encoded block size determined by the color moving image encoding apparatus in FIG. 1 (a processing unit when intra prediction processing or motion compensation prediction processing is performed). The maximum size of the encoding block) and the upper limit of the number of division layers (the number of layers of the encoding block divided hierarchically from the encoding block of the maximum size) are determined by the same procedure as that of the color moving image encoding apparatus. (Step ST42).

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

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 partition information of the partition P _i ⁿ belonging to the coding block B ⁿ included in the coding mode, and encodes the encoded data that is 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, compressed data, predictive differential coding parameters including transform block division flag, an intra prediction parameter / inter prediction parameters by variable length decoding the coded data according to each partition P _i ^n, the compressed data The prediction differential encoding parameter 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 color moving image encoding device side, the intra prediction parameter can be correctly decoded.

Hereinafter, the processing content of the variable length decoding part 41 is demonstrated concretely.
As shown in FIG. 6, the variable length decoding unit 41 includes a transform coefficient variable length decoding unit 51 that performs variable length decoding of orthogonal transform coefficients, which are compressed data, from encoded data multiplexed in a bit stream, and multiplexes the bit stream. Coding parameter variable for variable length decoding coding parameters such as input signal format information, coding mode, prediction differential coding parameter, intra prediction parameter / inter prediction parameter, motion information, block division information from coded coded data And a long decoding unit 52.

The transform coefficient variable length decoding unit 51 of the variable length decoding unit 41 arithmetically decodes the orthogonal transform coefficient using the occurrence probability corresponding to the context value of the orthogonal transform coefficient.
That is, the transform coefficient variable length decoding unit 51 arithmetically decodes the luminance component, the color difference component in the YUV 4: 2: 0 format, or the color difference component in the YUV 4: 4: 4 format as follows.

(1) Starting with a sub-block including PosLast, the SigCoeffGroupFlag indicating whether or not a non-zero orthogonal transform coefficient is included in the sub-block is arithmetically decoded in the reverse oblique scan order shown in FIG.
When SigCoeffGroupFlag indicates that a non-zero orthogonal transform coefficient is included in the sub-block, the following processes (2) to (6) are performed.
(2) Arithmetically decode significant_coeff_flag indicating whether or not the orthogonal transform coefficient at the position of each frequency component is non-zero in reverse diagonal scan order.

(3) For the orthogonal transform coefficient at the frequency component position indicating that significant_coeff_flag is non-zero in reverse diagonal scan order, arithmetically decodes coeff_abs_level_greater1_flag indicating whether the absolute value of the orthogonal transform coefficient is greater than 1 .
When coeff_abs_level_greater1_flag indicates that the absolute value of the orthogonal transform coefficient is not greater than 1, 1 is output as the absolute value of the orthogonal transform coefficient at the frequency component position.
(4) Whether the absolute value of the orthogonal transform coefficient is greater than 2 for the orthogonal transform coefficient at the frequency component position where coeff_abs_level_greater1_flag indicates that the absolute value of the orthogonal transform coefficient is greater than 1 in reverse diagonal scan order Coeff_abs_level_greater2_flag indicating that is arithmetically decoded.
When coeff_abs_level_greater2_flag indicates that the absolute value of the orthogonal transform coefficient is not greater than 2, 2 is output as the absolute value of the orthogonal transform coefficient at the frequency component position.

(5) For the orthogonal transform coefficient at the frequency component position indicating that significant_coeff_flag is non-zero in reverse diagonal scan order, arithmetically decodes coeff_sign_flag indicating the sign of the orthogonal transform coefficient, and at the frequency component position The sign of the positive and negative with respect to the absolute value of the orthogonal transform coefficient is determined.
(6) For the orthogonal transform coefficient at the frequency component position where coeff_abs_level_greater2_flag indicates that the absolute value of the orthogonal transform coefficient is greater than 2 in reverse diagonal scan order, the value obtained by subtracting 3 from the absolute value of the orthogonal transform coefficient A certain coeff_abs_level_minus3 is arithmetically decoded.
The absolute value of the orthogonal transform coefficient at the frequency component position is set to a value obtained by adding 3 to the value of coeff_abs_level_minus3, and the sign of the absolute value of the orthogonal transform coefficient at the frequency component position is determined by coeff_sign_flag.

  Here, as the occurrence probability used for arithmetic decoding of significant_coeff_flag, if the pixel size is 4 × 4 or 8 × 8, for example, refer to the context index value for YUV 4: 2: 0 as shown in FIG. Then, the context index value of each conversion coefficient in the color difference signal is specified, and the occurrence probability corresponding to the context index value (for example, the context index determined for each frequency position in each area of the probability state memory (not shown)) The occurrence probability corresponding to the value is stored).

However, for the color difference signal when the input signal is in the YUV 4: 2: 2 format, since the shape of the conversion block is a rectangle that is twice as long as the width, YUV 4: 2: as shown in FIG. Refer to the context index value for 2.
For the context index value for YUV 4: 2: 2, the assignment of the context index value indicating the region of the probability state memory is repeatedly applied two by two in the vertical direction.
In this way, even when the input signal is in the YUV 4: 2: 2 format, the context index value assignment table of the color difference component in the YUV 4: 2: 0 format can be reused, and the compression efficiency can be reduced with a small circuit scale. Can be increased.

When the coding mode of the partition P _i ⁿ belonging to the coding block B ⁿ output from the variable length decoding unit 41 is the intra coding mode, the changeover switch 42 outputs 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.

The intra prediction unit 43 receives the intra prediction parameter from the variable length decoding unit 41 (step ST45), like the intra prediction unit 4 in FIG. 1, on the basis of the intra prediction parameters, intra prediction for each partition P _i ⁿ By performing the process, an intra-predicted image (P _i ⁿ ) is generated (step ST46).
That is, the intra prediction unit 43 receives the intra prediction parameter from the variable length decoding unit 41, similarly to the intra prediction unit 4 in FIG. 1, for example, the index value of the intra prediction mode for the partition P _i ⁿ is 2 (average value If the 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 intra prediction unit 43 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 ).

Motion compensation unit 44 receives the inter prediction parameters from the changeover switch 42, similarly to the motion compensation prediction unit 5 of the color video encoding apparatus, based on the inter prediction parameters, inter-prediction processing for each partition P _i ⁿ To generate an inter predicted image (P _i ⁿ ) (step ST47).
That is, motion compensation unit 44, using one or more frames of reference images stored by the motion compensated prediction frame memory 49, by performing the motion compensation prediction processing on partition P _i ⁿ based on the inter prediction parameters, An inter prediction image (P _i ⁿ ) is generated.

  When the inverse quantization / inverse transform unit 45 receives the prediction difference encoding parameter including the transform block division flag from the variable length decoding unit 41, the inverse quantization / inverse transform unit 45 performs transform using the quantization parameter included in the prediction difference encoding parameter. For each transform block size determined according to the block partition flag, the compressed data related to the coding block output from the variable length decoding unit 41 is inversely quantized, and the transform block partition flag included in the prediction differential coding parameter is used. Inverse transform processing of compressed data after inverse quantization (for example, inverse DCT (Inverse Discrete Cosine Transform), inverse DST (Inverse Discrete Sine Transform), inverse KL transform, etc.) As a result, the compressed data after the inverse transform process is output to the adder 46 as a decoded prediction difference signal (a signal indicating a difference image before compression). (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).
Here, since the coding distortion occurs along the boundary of the transform block, the transform distortion is compensated for the boundary in the transform block. For small transform blocks, coding distortion at the transform block boundaries is not noticeable, so the minimum loop filter applied block size is signaled in the header, and coding is performed only for blocks whose transform block size is larger than the minimum loop filter applied block size. You may comprise so that distortion compensation may be applied. In this way, since unnecessary encoding distortion compensation can be omitted, the amount of calculation can be reduced while maintaining the image quality.

It is also known that coding distortion occurs as an offset of a pixel value near the edge of an image or in a flat portion.
For such coding distortion, the variable length decoding unit 41 performs variable length decoding of the adaptive pixel offset type and the pixel offset value for each predetermined block, and the adaptive pixel offset type determines the pixel offset value of the edge portion. In the case where the compensation is indicated, the coding distortion is compensated by adding the offset value of the pixel value for each edge type in the block to the decoded image.
In addition, when the adaptive pixel offset type indicates that the pixel offset value of the portion that is not the edge portion is compensated, the pixel offset value for each sub-level of the pixel value in the block is added to the decoded image. Compensate for coding distortion.

Here, when the signal to be decoded is in the 4: 4: 4 format, texture type texture type information indicating whether the pixel offset of the edge part or the pixel offset of the other part is compensated in the block. The variable length decoding unit 41 performs variable length decoding.
When the texture type indicates an edge portion, the edge direction information common to all color components is variable-length decoded by the variable-length decoding unit 41, and the type of edge common to all color components is determined. For each color component, the pixel offset value is subjected to variable length decoding by the variable length decoding unit 41, and pixel offset compensation processing is performed.

On the other hand, when the texture type indicates that it is not an edge portion, the variable length decoding unit 41 performs variable length decoding on the level information of the pixel value independently for each color component, and the sub level of the pixel value in the block independently for each color component. The pixel offset value is subjected to variable length decoding by the variable length decoding unit 41 for each time, and pixel offset compensation processing is performed.
In this way, it is possible to suitably decode the 4: 4: 4 format encoded data encoded by the color moving image encoding apparatus of FIG.

In addition, since the division shape of the transform block is different between the luminance signal and the color difference signal, the coding distortion compensation is configured to specify and process the division shape of the transformation block for each of the luminance signal and the color difference signal.
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.
The processes in steps ST43 to ST49 are repeatedly performed until the processes for the partitions P _i ⁿ belonging to all the coding blocks B ⁿ are completed (step ST51).

  As apparent from the above, according to the first embodiment, when the transform / quantization unit 7 performs the transform / quantization process on the luminance signal of the difference image generated by the subtraction unit 6, the input signal is When the YUV4: 2: 2 format is used, the conversion block shape of the color difference signal is always divided into rectangles whose vertical length is twice the horizontal width, and when the obtained conversion coefficient is encoded by the variable length encoding unit 13, By applying the context index value assigned to the YUV4: 2: 0 color difference component conversion coefficient two times in the vertical direction, the color difference of YUV4: 2: 2 is increased without increasing the circuit scale. There is an effect that the encoding efficiency of the signal can be increased.

  Also in the color moving image decoding apparatus, if the input signal is in the YUV 4: 2: 2 format, the conversion block shape of the color difference signal is always divided into rectangles whose vertical and horizontal dimensions are twice, and the obtained conversion coefficients are variable. When decoding by the long decoding unit 41, a color moving image code is obtained by applying a context index value assigned to YUV4: 2: 0 chrominance component conversion coefficients in the vertical direction twice. The bit stream generated by the encoding device can be suitably decoded.

Embodiment 2. FIG.
FIG. 19 is a block diagram showing a color moving picture coding apparatus according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. When the encoding mode determined by the encoding control unit 1 is the correlation use prediction mode, the correlation use prediction unit 61 has a signal format of the first color component corresponding to the luminance component (Y component) of the YUV signal. A prediction image is generated by performing intra-frame prediction encoding in the case of the 4: 0: 0 format, or a locally decoded image of the first color component included in another encoded picture is A process for generating a prediction image is performed by performing inter-frame prediction encoding using the reference image.
The second color component and the third color component corresponding to other color components (U component and V component) of the YUV signal are the same as those of the first color component included in the same encoded picture. A process for generating a prediction image is performed by performing inter-frame prediction encoding using a locally decoded image as a reference image.
The correlation usage prediction unit 61 constitutes a predicted image generation unit.

In FIG. 19, the coding control unit 1, the block division unit 2, the changeover switch 3, the correlation use prediction unit 61, the motion compensation prediction unit 5, the subtraction unit 6, and the transform / quantization that are components of the color moving image coding apparatus. Unit 7, inverse quantization / inverse transform unit 8, addition unit 9, intra prediction memory 10, loop filter unit 11, motion compensated prediction frame memory 12, and variable length coding unit 13, each of which has dedicated hardware (for example, It is assumed that the CPU is a semiconductor integrated circuit, a one-chip microcomputer, or a memory), but the color moving image encoding device may be a computer.
When the color moving image encoding apparatus is configured by a computer, the intra prediction memory 10 and the motion compensated prediction frame memory 12 are configured on the memory of the computer, and the encoding control unit 1, the block division unit 2, and the changeover switch 3 are configured. , Correlation use prediction unit 61, motion compensation prediction unit 5, subtraction unit 6, transformation / quantization unit 7, inverse quantization / inverse transformation unit 8, addition unit 9, loop filter unit 11 and variable length coding unit 13 All or a part of the program describing the contents may be stored in the memory of the computer, and the CPU of the computer may execute the program stored in the memory.

FIG. 20 is a block diagram showing the correlation use prediction unit 61 of the color moving image encoding apparatus according to Embodiment 2 of the present invention.
In FIG. 20, the correlation calculation unit 62 includes an inter-screen reference pixel Rec ′ _L (in FIG. 22A) that is a pixel value adjacent to the upper end and the left end of the block at the same position as the prediction target block in the reference image. , And the reference pixel Rec _C (in FIG. 22B), which is a decoded pixel value of the processing target signal adjacent to the upper end and the left end of the prediction target block. Are used to calculate correlation parameters α and β used for prediction.
The correlation use predicted image generation unit 63 performs a process of generating a predicted image Pred _C using the correlation parameters α and β calculated by the correlation calculation unit 62 and the inter-screen reference pixel Rec ′ _L.

FIG. 23 is a block diagram showing a color moving picture decoding apparatus according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
When the coding mode that has been variable-length decoded by the variable-length decoding unit 41 is the correlation-use prediction mode, the correlation use prediction unit 71 uses the Generate predicted image by performing intra-frame predictive decoding when format is 4: 0: 0 format, or refer to decoded image of first color component included in other decoded pictures A process for generating a predicted image is performed by performing inter-frame predictive decoding using the image.
Also, for the second color component and the third color component corresponding to other color components (U component and V component) of the YUV signal, the first color component included in the same decoded picture is decoded. A process for generating a predicted image is performed by performing inter-frame predictive decoding using the image as a reference image.
The correlation usage prediction unit 71 constitutes a predicted image generation unit.

In FIG. 23, the variable length decoding unit 41, the changeover switch 42, the correlation use prediction unit 71, the motion compensation unit 44, the inverse quantization / inverse transformation unit 45, the addition unit 46, and the intra prediction, which are components of the color moving image decoding apparatus. Each of the memory 47, the loop filter unit 48, and the motion compensation prediction frame memory 49 is configured by dedicated hardware (for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or a memory). However, the color moving image decoding apparatus may be configured by a computer or the like.
When the color moving image decoding apparatus is configured by a computer, the intra prediction memory 47 and the motion compensated prediction frame memory 49 are configured on the computer memory, and the variable length decoding unit 41, the changeover switch 42, and the correlation use prediction unit 71. All or part of the program describing the processing contents of the motion compensation unit 44, inverse quantization / inverse transformation unit 45, addition unit 46 and loop filter unit 48 is stored in the memory of the computer, and the CPU of the computer May execute a program stored in the memory.

FIG. 24 is a block diagram showing the correlation use prediction unit 71 of the color moving image decoding apparatus according to Embodiment 2 of the present invention.
In FIG. 24, the correlation calculation unit 72 includes an inter-screen reference pixel Rec ′ _L (in FIG. 22A) that is a pixel value adjacent to the upper end and the left end of the block at the same position as the prediction target block in the reference image. , And the reference pixel Rec _C (in FIG. 22B), which is a decoded pixel value of the processing target signal adjacent to the upper end and the left end of the prediction target block. Are used to calculate correlation parameters α and β used for prediction.
The correlation use predicted image generation unit 73 performs a process of generating a predicted image Pred _C using the correlation parameters α and β calculated by the correlation calculation unit 72 and the inter-screen reference pixel Rec ′ _L.

  In the first embodiment, the color moving image encoding apparatus encodes the luminance signal and the color difference signal at the same time. However, the color moving image encoding apparatus has an input signal in the 4: 4: 4 format. In this case, it is assumed that each component is in the YUV4: 0: 0 format, and only the first color component corresponding to the luminance component (Y component) of the YUV signal is first encoded to localize the first color component. The decoded image is stored in the motion compensated prediction frame memory 12, and then the other color components (U component) are used by using the locally decoded image of the first color component stored in the motion compensated prediction frame memory 12 as a reference image. And the V component) may be encoded by assuming that the image is in the YUV4: 0: 0 format.

Whether the variable length coding unit 13 performs predictive coding between the color components of the YUV 4: 4: 4 format as described above, or performs predictive coding between pictures as in the first embodiment. Is encoded with a variable length and multiplexed into a bit stream.
When the prediction configuration flag indicates that encoding is performed with a configuration in which predictive encoding is performed between the color components of the 4: 4: 4 format, the three YUV4: 0: 0 images generated as described above are collected. Thus, an access unit delimiter, which is information for recognizing one picture (access unit) as an access unit for display or the like, is multiplexed at the head of the picture.

FIG. 21 is an explanatory diagram showing a locally decoded image used as a reference image.
In the next picture, as shown in FIG. 21, for the first color component corresponding to the Y component, the locally decoded image of the first color component of the previous picture stored in the motion compensated prediction frame memory 12 is used as the reference image. And encoded as YUV4: 0: 0 format.
Other color components corresponding to the U component and the V component are encoded using the locally decoded image of the first color component of the picture as a reference image, similarly to the previous picture.

Here, in the motion compensation prediction process between color components, since the motion vector is zero and the reference image is specified, the variable length coding of the motion vector and the reference image is not performed.
In prediction between color components, in addition to motion compensation prediction from a reference image, for example, a correlation use signal prediction may be selected using a reference image.

式（１），（２）において、Ｉは処理対象となる予測ブロックの１辺の画素数の２倍の値である。 Next, the operation will be described.
First, the processing contents of the color moving image encoding apparatus will be described.
However, except that a correlation usage prediction unit 61 is provided instead of the intra prediction unit 4, the processing is the same as in the first embodiment, and only the processing contents of the correlation usage prediction unit 61 will be described here.
When the coding mode determined by the coding control unit 1 is the correlation use prediction mode, the correlation calculation unit 62 of the correlation use prediction unit 61 is the same as the prediction target block in the reference image, as shown in FIG. An inter-screen reference pixel Rec ′ _L (pixels hatched in FIG. 22A) which is a pixel value adjacent to the upper end and left end of the block at the position, and the upper end and left end of the prediction target block Using the in-screen reference pixel Rec _C (pixels hatched in FIG. 22B) that is the decoded pixel value of the adjacent processing target signal, the following equation (1) and As shown in Expression (2), a process of calculating correlation parameters α and β used for prediction is performed.

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

When the correlation calculation unit 62 calculates the correlation parameters α and β, the correlation use prediction image generation unit 63 of the correlation use prediction unit 61 uses the correlation parameters α and β and the inter-screen reference pixel Rec ′ _L as follows: As shown in (3), a predicted image Pred _C is generated.

Thereby, in the prediction process between color components, since a prediction image with a small residual can be produced | generated, encoding efficiency can be improved.
In addition, a 4: 4: 4 format image can be compressed with high efficiency only by the luminance component encoding circuit.

Next, processing contents of the color moving image decoding apparatus will be described.
If the variable length decoding unit 41 indicates that the prediction configuration flag is decoded from the encoded data and the prediction configuration flag indicates that the prediction encoding is performed between the color components of the 4: 4: 4 format, the access unit By decoding the delimiter, three YUV4: 0: 0 format images are recognized as one picture (access unit) that is an access unit for display or the like.
Then, the first color component is decoded as the YUV4: 0: 0 format, the decoded image of the first color component is stored in the motion compensation prediction frame memory 49, and the first color component stored in the motion compensation prediction frame memory 49 is stored. A decoded image of one color component is used as a reference image, and images of other color difference components (for example, U component and V component) are regarded as being in the YUV4: 0: 0 format and decoded.

  In the next picture, for the first color component, the decoded image of the first color component of the previous picture stored in the motion compensated prediction frame memory 49 is used as a reference image, and the YUV4: 0: 0 format is used. Decoding is performed on the other color components (U component and V component) using the decoded image of the first color component of the picture as a reference image, similarly to the previous picture.

That is, the correlation calculation unit 72 of the correlation use prediction unit 71, when the encoding mode variable length decoded by the variable length decoding unit 41 is the correlation use prediction mode, similarly to the correlation calculation unit 62 of FIG. In-screen reference pixel Rec ′ _L (pixels hatched in FIG. 22A) which is a pixel value adjacent to the upper end and the left end of the block at the same position as the prediction target block in FIG. Using in-screen reference pixels Rec _C (pixels hatched in FIG. 22B) which are decoded pixel values of the processing target signal adjacent to the upper end and the left end of the prediction target block As shown in the above formulas (1) and (2), the processing for calculating the correlation parameters α and β used for prediction is performed.

When the correlation calculation unit 72 calculates the correlation parameters α and β, the correlation use prediction image generation unit 73 of the correlation use prediction unit 71 calculates the correlation parameters α and β as well as the correlation use prediction image generation unit 63 of FIG. Using the inter-screen reference pixel Rec ′ _L , a predicted image Pred _C is generated as shown in the above equation (3).

Here, when performing prediction between color components, the variable-length decoding unit 41 has variable-length prediction scheme information indicating whether to apply a motion compensation prediction mode or a correlation use prediction mode as a prediction mode for each block. Decrypt.
When the prediction method information indicates that the motion compensation prediction mode is applied as the prediction mode, the motion compensation prediction is performed using the first color component as a reference image and a block in an area identified with a motion vector of zero as a prediction value. Process. Therefore, in the motion compensation prediction mode between color components, variable length decoding of the motion vector and the reference image is not performed.
When the prediction method information indicates that the correlation use prediction mode is to be applied as the prediction mode, a prediction image is generated by performing the above-described correlation use prediction process.
That is, the color moving image decoding apparatus according to the second embodiment includes a motion compensation prediction mode and a correlation use prediction mode as prediction modes. Other processes are the same as those of the color moving image decoding apparatus according to the first embodiment.
As a result, in the color moving image decoding apparatus according to the second embodiment, the encoded data compressed as described above can be suitably decoded only by the luminance component decoding circuit, so that the circuit scale can be kept small. Can do.

In the second embodiment, the color moving image encoding apparatus in which the correlation use prediction unit 61 is mounted instead of the intra prediction unit 4 is shown. However, as shown in FIG. 25, instead of the intra prediction unit 4. Alternatively, the correlation use adaptive prediction unit 81 may be implemented.
FIG. 26 is a block diagram showing a correlation use adaptive prediction unit 81 of the color moving picture coding apparatus according to Embodiment 2 of the present invention.
In FIG. 26, when the coding mode determined by the coding control unit 1 is the intra prediction mode, the changeover switch 82 outputs the intra-screen reference pixel to the intra prediction unit 83, and the coding mode is the correlation use prediction mode. If it is, the process of outputting the in-screen reference pixel to the correlation use prediction unit 84 is performed.

When the encoding mode determined by the encoding control unit 1 is the intra prediction mode, the intra prediction unit 83 performs a process of generating an intra prediction image by performing the same intra prediction process as that of the intra prediction unit 4 in FIG. carry out.
When the encoding mode determined by the encoding control unit 1 is the correlation use prediction mode, the correlation use prediction unit 84 performs the same correlation use prediction process as the correlation use prediction unit 61 in FIG. Perform the process to generate.
Therefore, when the correlation use adaptive prediction unit 81 is implemented instead of the intra prediction unit 4, if the encoding mode determined by the encoding control unit 1 is the intra prediction mode, intra prediction is performed according to the method of the first embodiment. If an image is generated and the coding mode determined by the coding control unit 1 is the correlation use prediction mode, an intra prediction image is generated by the method of the second embodiment.
In this case, the variable length coding unit 13 performs variable length coding on prediction scheme information indicating which prediction mode is applied for each block.

In the second embodiment, the color moving image decoding device in which the correlation use prediction unit 71 is mounted instead of the intra prediction unit 43 is shown, but as shown in FIG. 27, instead of the intra prediction unit 43, The correlation use adaptive prediction unit 91 may be implemented.
FIG. 28 is a block diagram showing the correlation use adaptive prediction unit 91 of the color moving image decoding apparatus according to Embodiment 2 of the present invention.
In FIG. 28, when the encoding mode that has been variable length decoded by the variable length decoding unit 41 is the intra prediction mode, the changeover switch 92 outputs the intra-screen reference pixel to the intra prediction unit 93, and the encoding mode is correlated. In the case of the prediction mode, a process of outputting the in-screen reference pixels to the correlation use prediction unit 94 is performed.

When the encoding mode variable-length decoded by the variable-length decoding unit 41 is the intra-prediction mode, the intra-prediction unit 93 performs an intra-prediction process similar to the intra-prediction unit 43 in FIG. 4 and generates an intra-prediction image. Perform the process.
When the encoding mode variable length decoded by the variable length decoding unit 41 is the correlation use prediction mode, the correlation use prediction unit 94 performs the same correlation use prediction process as the correlation use prediction unit 71 of FIG. A process for generating an image is performed.
Therefore, when the correlation use adaptive prediction unit 91 is installed instead of the intra prediction unit 43, if the encoding mode variable length decoded by the variable length decoding unit 41 is the intra prediction mode, the method of the first embodiment is used. If the intra-predicted image is generated and the coding mode that has been variable-length decoded by the variable-length decoding unit 41 is the correlation use prediction mode, the intra-predicted image is generated by the method of the second embodiment.
In the second embodiment, an image in the 4: 4: 4 format has been described as an example. Naturally, if the size of each color component is the same, a plurality of color components such as a multi-channel image and a hyperspectral image are included. Similar processing can be performed for the image format possessed.

Embodiment 3 FIG.
In the third embodiment, encoding and decoding processing different from the encoding and decoding processing described in the second embodiment will be described.
FIG. 19 is a block diagram showing a color moving image encoding apparatus according to the third embodiment. Since this is the same as the configuration diagram showing the color moving image encoding apparatus described in the second embodiment, the explanation is omitted. Omitted.
FIG. 20 is the same as the configuration diagram showing the correlation usage prediction unit 61 described in the second embodiment, but in the third embodiment, the correlation calculation unit 62 of the correlation usage prediction unit 61 is an encoding control unit. When the coding mode determined by 1 is the correlation use prediction mode in the intra coding mode, whether the correlation parameters α and β used for prediction are calculated using the encoded pixel values (correlation parameters α and β Mode in which multiplexing to bitstream is not necessary), whether correlation parameters α and β used for prediction are calculated using pixel values in the encoding target block (mode in which correlation parameters α and β need to be multiplexed to bitstream) ), Any one of the processes is performed.
The correlation use predicted image generation unit 63 performs a process of generating a predicted image Pred _C using the correlation parameters α and β calculated by the correlation calculation unit 62 and the inter-screen reference pixel Rec ′ _L.

FIG. 23 is a block diagram showing a color moving image decoding apparatus according to the third embodiment, but since it is the same as the block diagram showing the color moving image decoding apparatus described in the second embodiment, the description thereof is omitted. .
FIG. 24 is the same as the configuration diagram showing the correlation usage prediction unit 71 described in the second embodiment, but in the third embodiment, the correlation calculation unit 72 of the correlation usage prediction unit 71 is a variable length decoding unit. When the decoded decoding mode is a mode in which the correlation parameters α and β used for prediction in the correlation use prediction mode in the intra coding mode are calculated using the decoded pixel values (to the bit stream of the correlation parameters α and β) The correlation parameters α and β used for prediction are calculated using the decoded pixel values, and the calculated correlation parameters α and β are output to the correlation-use predicted image generation unit 73. When the coding mode decoded by the variable length decoding unit is a mode in which the correlation parameters α and β used for prediction in the correlation use prediction mode in the intra coding mode are multiplexed in the bitstream (correlation parameters α and β The mode in which multiplexing to the bit stream is necessary), and correlation parameters α and β decoded by the variable length decoding unit are output to the correlation use predicted image generation unit 73.
The correlation use predicted image generation unit 73 performs a process of generating a predicted image Pred _C using the correlation parameters α and β output from the correlation calculation unit 72 and the inter-screen reference pixel Rec ′ _L.

Next, the operation of the encoding process will be described.
First, the processing contents of the color moving image encoding apparatus will be described. However, the configuration of the color moving image encoding device and the configuration of the correlation use prediction unit 61 are the same as those in the second embodiment.
The correlation calculation unit 62 of the correlation usage prediction unit 61 of the third embodiment uses the correlation parameter α used for prediction when the coding mode determined by the coding control unit 1 is the correlation usage prediction mode in the intra coding mode. , Β is calculated using decoded pixel values (a mode in which the correlation parameters α, β are not required to be multiplexed to the bit stream), or the correlation parameters α, β used for prediction are used as the pixel values in the encoding target block Either calculation is performed (a mode in which the correlation parameters α and β need to be multiplexed on the bit stream), or any one of the processes is performed.
In the case of the mode in which the correlation parameters α and β are calculated using the decoded pixel values (the mode in which the correlation parameters α and β are not required to be multiplexed into the bit stream), as shown in FIG. Inter-screen reference pixel Rec ′ _L (pixels hatched in FIG. 22A) that is a pixel value adjacent to the top and left ends of the block at the same position as the prediction target block, and the prediction target Using the in-screen reference pixel Rec _C (pixels hatched in FIG. 22B) that is the decoded pixel value of the processing target signal adjacent to the upper end and the left end of the block As in Embodiment 2, as shown in Equation (1) and Equation (2), processing for calculating correlation parameters α and β used for prediction is performed.
In Expressions (1) and (2), I is a value twice the number of pixels on one side of the prediction block to be processed.
In a mode in which the correlation parameters α and β are calculated using the pixel values in the encoding target block (a mode in which the correlation parameters α and β need to be multiplexed on the bit stream), the pixels in the decoded reference block Rec ′ _L (pixels that are shaded in FIG. 29A) and pixels Rec _C in the encoding target block (pixels that are shaded in FIG. 29B) As shown in the above formulas (1) and (2), a process of calculating correlation parameters α and β used for prediction is performed.
In the mode in which the correlation parameters α and β used for prediction are calculated using the pixel values in the encoding target block, it is necessary to multiplex the correlation parameters α and β used on the decoding side into the bit stream. The parameters α and β are output to the variable length coding unit.
In the case of a mode in which the correlation parameters α and β used for prediction are calculated using decoded pixel values (a mode in which the correlation parameters α and β are not required to be multiplexed on the bit stream), the decoding side encodes Since the correlation parameters α and β can be calculated by performing the same processing as in step 1, it is not necessary to multiplex the correlation parameters α and β into the bit stream.
Select either the mode for calculating the correlation parameters α and β used for prediction using the decoded pixel values or the mode for calculating the correlation parameters α and β used for prediction using the pixel values in the encoding target block. This is determined by the encoding control unit 1.
When the correlation calculation unit 62 calculates the correlation parameters α and β, the correlation use predicted image generation unit 63 of the correlation use prediction unit 61 uses the correlation parameters α and β and the inter-screen reference pixel Rec ′ _L to execute the above-described implementation. Similar to the second embodiment, a predicted image Pred _C is generated as shown in Expression (3).

  Thereby, in the prediction process between color components, since a prediction image with a small residual can be produced | generated, encoding efficiency can be improved.

  In the mode in which the correlation parameters α and β are calculated using the pixel values in the encoding target block, it is necessary to multiplex the correlation parameters α and β into the bitstream, which is related to the correlation parameters α and β. In order to suppress the code amount, the block size to which a mode (a mode in which the correlation parameters α and β need to be multiplexed on the bitstream) calculated using the pixel value in the encoding target block is larger than a predetermined size. You may restrict in some cases. That is, the block size to which the mode (mode in which the correlation parameters α and β need to be multiplexed on the bit stream) calculated by the encoding control unit 1 using the pixel values in the encoding target block is applicable is larger than the predetermined size. When the block size is larger than the predetermined size, it is necessary to multiplex the correlation parameters α and β into the bit stream. However, when the block size is smaller than the predetermined size, the correlation parameters α and β Multiplexing to the bit stream is not necessary. In other words, if the block size is large, even if the correlation parameters α and β are multiplexed on the bit stream, the ratio of overhead to the data amount can be reduced, so that the code amount can be suppressed.

Further, as another embodiment of a method for calculating correlation parameters α and β using pixel values in a block to be encoded (mode in which correlation parameters α and β need to be multiplexed to a bit stream), Clustering is performed by a predetermined method using the pixels Rec ′ _L in the reference block (pixels shaded in FIG. 29A), and the pixels Rec ′ _L in the reference block are assigned a predetermined number of classes. Classify into: FIG. 30 shows an example in which the pixels in the reference block are classified into, for example, four classes. The pixel Rec _C in the encoding target block is classified into the same class as the pixel at the same position in the reference block. Using the pixels belonging to the same class as the reference block and the encoding target block, the processing for calculating the correlation parameters α and β used for prediction is performed for each class as shown in the above formulas (1) and (2). To do. The correlation parameters α and β calculated for each class are output to the variable length coding unit for multiplexing in the bit stream. Note that since clustering is performed using decoded pixels, information relating to clustering such as which class each pixel is classified does not need to be bitstream multiplexed. In addition, in order to suppress the amount of code related to the correlation parameters α and β, a block to which a mode (a mode in which the correlation parameters α and β need to be multiplexed on the bit stream) calculated using pixel values in the encoding target block can be applied. You may restrict | limit when size is larger than predetermined size. That is, the block size to which the mode (mode in which the correlation parameters α and β need to be multiplexed on the bit stream) calculated by the encoding control unit 1 using the pixel values in the encoding target block is applicable is larger than the predetermined size. When the block size is larger than the predetermined size, it is necessary to multiplex the correlation parameters α and β into the bit stream. However, when the block size is smaller than the predetermined size, the correlation parameters α and β Multiplexing to the bit stream is not necessary. In other words, if the block size is large, even if the correlation parameters α and β are multiplexed on the bit stream, the ratio of overhead to the data amount can be reduced, so that the code amount can be suppressed.
Since the operation of the encoding process other than the above operation is the same as that of the second embodiment, description thereof is omitted.

Next, the operation of the decoding process will be described.
Since the operation of the variable length decoding unit 41 is the same as that of the first embodiment, description thereof is omitted.
Next, when the encoding mode of the partition P _i ⁿ belonging to the encoding block B ⁿ output from the variable length decoding unit 41 is the intra encoding mode, the changeover switch 42 is output from the variable length decoding unit 41 When the intra prediction parameter is output to the intra prediction unit 43 and 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.
The intra prediction unit 43 receives the intra prediction parameter from the variable length decoding unit 41 (Step of Fig. 5 ST45), like the intra prediction unit 4 in FIG. 1, on the basis of the intra prediction parameters, each partition P _i ⁿ Intra prediction image (P _i ⁿ ) is generated by performing intra prediction processing for (step ST46 in FIG. 5).
That is, the intra prediction unit 43 receives the intra prediction parameter from the variable length decoding unit 41, similarly to the intra prediction unit 4 in FIG. 1, for example, the index value of the intra prediction mode for the partition P _i ⁿ is 2 (average value If the 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.

In the case where the index value of the intra prediction mode is other than 2 (average value prediction) and the directionality prediction mode, the intra-partition P _i ⁿ is based on the prediction direction vector v _p = (dx, dy) indicated by the index value. The predicted value of the pixel is generated.
Hereinafter, a case where the intra prediction parameter is the correlation use prediction mode will be described.
The correlation calculation unit 72 of the correlation use prediction unit 71 is a mode in which the correlation parameters α and β used for prediction are calculated using decoded pixel values (there is no need to multiplex the correlation parameters α and β into the bitstream). Mode), as shown in FIG. 22, the inter-screen reference pixel Rec ′ _L , which is a pixel value adjacent to the upper end and the left end of the block at the same position as the prediction target block in the reference image (FIG. 22A). In FIG. 22, pixels that are shaded (hatched)) and in-screen reference pixels Rec _C (FIG. 22 (FIG. 22 (FIG. 22 ()) that are decoded pixel values of the processing target signal adjacent to the upper and left ends of the prediction target block). In b), a process of calculating correlation parameters α and β used for prediction as shown in the above formulas (1) and (2) using the shaded pixels). carry out.
In Expressions (1) and (2), I is a value twice the number of pixels on one side of the prediction block to be processed.
In the case of the mode in which the correlation parameters α and β used for prediction are decoded from the bitstream, the correlation parameters α and β decoded by the variable length decoding unit 41 are output to the correlation use predicted image generation unit 73.

When the correlation calculation unit 72 calculates the correlation parameters α and β, the correlation use prediction image generation unit 73 of the correlation use prediction unit 71 calculates the correlation parameters α and β as in the correlation use prediction image generation unit 63 of FIG. Using the inter-screen reference pixel Rec ′ _L , a predicted image Pred _C is generated as shown in the above equation (3).

Further, as another embodiment in the mode in which the correlation parameters α and β are decoded from the bit stream, the pixel Rec ′ _L in the decoded reference block (the pixel which is shaded in FIG. 29A) ) To classify the pixels Rec ′ _L in the reference block into a predetermined number of classes. FIG. 30 shows an example in which the pixels in the reference block are classified into four classes. The pixel Rec _C in the decoding target block is classified into the same class as the pixel at the same position in the reference block. Using the pixels belonging to the same class as the reference block and the encoding target block, the prediction image Pred _C is generated as shown in the above equation (3) using the correlation parameters α and β that are variable-length decoded for each class. To do.

Note that when the encoding apparatus is in a mode in which the correlation parameters α and β used for prediction are calculated using the pixel values in the decoding target block (a mode in which the correlation parameters α and β need to be multiplexed on the bit stream). When the applicable block size is limited to a case where the block size is larger than the predetermined size, the correlation parameters α and β used for the prediction are used only when the block size of the decoding target block is larger than the predetermined size. (Correlation parameters α and β are not required to be multiplexed into the bit stream), or whether the correlation parameters α and β used for prediction are decoded from the bit stream (correlation parameters α and β into the bit stream) Mode information indicating a mode that requires multiplexing) is decoded, and the above processing is performed according to the decoded mode. A mode in which the correlation parameters α and β used for prediction are calculated using the decoded pixel values when the block size of the decoding target block is equal to or smaller than a predetermined size (there is no need to multiplex the correlation parameters α and β into the bit stream) Mode) is always applied.
Thereby, in the color moving image encoding device and the color moving image decoding device according to the third embodiment, a prediction image with a small residual can be generated in the prediction process between color components as described above. Encoding efficiency can be increased. The characteristic part of the third embodiment is a predicted image generation unit. If this predicted image generation unit is provided, the above-described effects of the color moving image encoding device and the color moving image decoding device of the third embodiment are obtained. Can be obtained.

  Note that the operation of the decoding process other than the above operation is the same as that of the second embodiment, and thus the description thereof is omitted.

Embodiment 4 FIG.
In the fourth embodiment, encoding and decoding processes different from the encoding and decoding processes described in the second and third embodiments will be described.
In the following description, unless otherwise specified, it is assumed that the input video signal is a YUV 4: 4: 4 signal, and the first, second, and third color components are Y, U, and V components, respectively. As will be described, it is assumed that the input video signal is an RGB signal, and the first, second, and third color components may be any combination of three components. Further, the input video signal may be a signal including more color components than the three primary colors, and for the fourth and subsequent color components, it is possible to apply the same processing procedure as the second and third color components. it can.

FIG. 31 is a block diagram showing a color moving image encoding apparatus according to the fourth embodiment. In the figure, the same reference numerals as those in FIG.
When the encoding mode determined by the encoding control unit 1 is the inter prediction mode, the inter prediction unit 101 is different from the encoded first color component corresponding to the luminance component (Y component) of the YUV signal. A process for generating a predicted image is performed by performing inter-frame predictive coding using a locally decoded image of a first color component having a POC (Picture Order Count) as a reference image.
In addition, for the second color component and the third color component corresponding to the U component and the V component of the YUV signal, the local decoded image of the different color component having the same POC that has been encoded is used as a reference image. Predictive encoding is performed to generate a prediction image, or a different POC that has been encoded, and a locally decoded image having the same color component as the color component to be encoded is used as a reference image to generate an interframe prediction code. The process which produces | generates an estimated image is implemented by implementing.
The inter prediction unit 101 constitutes a predicted image generation unit.

FIG. 32 is a block diagram showing the inter prediction unit 101 of the color moving image coding apparatus according to Embodiment 4 of the present invention.
In FIG. 32, the motion compensated prediction unit 5 is stored in the motion compensated prediction frame memory 12, and uses a locally decoded image having the same color component as the encoding target color component and a different POC as a reference image, and performs interframe predictive coding. The process which produces | generates an estimated image is implemented by implementing.
The correlation use prediction unit 61 is stored in the motion compensation prediction frame memory 12, and performs interframe prediction encoding using a locally decoded image having a color component different from the color component to be encoded and having the same POC as a reference image. Thus, a process for generating a predicted image is performed.

The inter prediction parameters output from the inter prediction unit 101 are entropy encoded by the variable length encoding unit 13 and multiplexed into a bitstream.
32 is the same as the configuration diagram showing the correlation usage prediction unit 61 described in Embodiments 2 and 3 above, and thus the description thereof is omitted.
FIG. 38 is a block diagram showing a color moving image decoding apparatus according to the fourth embodiment. In the figure, the same reference numerals as those in FIG.
When the encoding mode decoded by the variable length decoding unit 41 is the inter prediction mode, the inter prediction unit 111 is different in that the first color component corresponding to the luminance component (Y component) of the YUV signal has been decoded. Using the decoded image of the first color component having POC as a reference image, a process for generating a predicted image is performed by performing interframe predictive coding.
Further, for the second color component and the third color component corresponding to the U component and the V component of the YUV signal, inter-frame prediction is performed using a decoded image of a different color component having the same POC that has been decoded as a reference image. By generating a predicted image by performing encoding, or by performing inter-frame prediction using a decoded image having a different POC that has been decoded and having the same color component as the decoding target color component as a reference image A process for generating a predicted image is performed.
FIG. 39 is a block diagram showing the inter prediction unit 111 of the color moving image decoding apparatus according to Embodiment 4 of the present invention.
In FIG. 39, the motion compensation unit 44 is stored in the motion compensation prediction frame memory 49, and performs inter-frame prediction using a decoded image having the same color component as the decoding target color component and a different POC as a reference image. A process for generating a predicted image is performed.
The correlation use prediction unit 71 is stored in the motion compensated prediction frame memory 49 and performs prediction between frames using a decoded image having a color component different from the color component to be decoded and having the same POC as a reference image. The process to generate is performed.
FIG. 33 is an explanatory diagram showing a locally decoded image used as a reference image. In the fourth embodiment, first, intra-frame prediction coding is performed using a picture (hereinafter referred to as a first color component picture) composed only of a first color component corresponding to a luminance component (Y component) of a YUV signal as an I picture. Then, the locally decoded image of the first color component is stored in the motion compensated prediction frame memory 12. In the next first color component picture, as shown in FIG. 33, the locally decoded image of the previous first color component picture stored in the motion compensated prediction frame memory 12 is used as a reference image (temporal direction prediction reference image). Encode as 4: 0: 0 format.
For a picture composed of only the third color component corresponding to the V component (hereinafter referred to as third color component picture), the code stored in the motion compensated prediction frame memory is the same as the motion compensated prediction of the first color component. A predicted image is generated by using a locally decoded image of the same color component picture (third color component picture) as the conversion target as a reference image (temporal direction prediction reference image), or the same POC stored in the motion compensated prediction frame memory Is used as a reference image (inter-color component prediction reference image) to generate a predicted image.
For a picture composed of only the second color component corresponding to the U component (hereinafter referred to as the second color component picture), the code stored in the motion compensated prediction frame memory is the same as the motion compensated prediction of the first color component. A prediction image is generated by using a locally decoded image of the same color component picture (second color component picture) as the conversion target as a reference image (temporal direction prediction reference image), or the same POC stored in the motion compensated prediction frame memory Is used as a reference image (inter-color component prediction reference image) to generate a prediction image.
In addition, the process which produces | generates a prediction image using a time direction prediction reference image is performed in the motion compensation prediction part 5, and the process which produces | generates a prediction image using the prediction reference image between color components is performed in the correlation utilization prediction part 61. FIG.

Next, the operation will be described.
First, the processing contents of the color moving image encoding apparatus will be described.
However, except that the inter prediction unit 101 is provided instead of the motion compensation prediction unit 5 and the motion compensation prediction unit 5 and the correlation use prediction unit 61 are provided in the inter prediction unit 101, the same as in the first embodiment. It is the same. The correlation usage prediction unit 61 in the second embodiment uses a block in the same position as the prediction target block in the reference image as a reference block, but the correlation usage prediction unit 61 in the fourth embodiment uses the block in the reference image. The difference is that a block at an arbitrary position is used as a reference block. That is, similarly to the motion compensation prediction unit 5 that generates a prediction image using a locally decoded image of the same color component picture as the encoding target stored in the motion compensation prediction frame memory 12 as a reference image (temporal direction prediction reference image), A motion vector (included in the inter prediction parameter) indicating the position of the reference block is encoded by the variable length encoding unit 13. Similar to the correlation use prediction unit 61 in the second embodiment, a block in the reference image at the same position as the prediction target block is set as a reference block, that is, the motion vector is fixed to zero, and the variable length code of the motion vector is set. (The mode in which neither the motion vector nor the reference image index is variable-length encoded) may be used.

なおＮの値および内挿フィルタ係数を色成分ごとに異なる値に設定するようにしてもよい。
相関利用予測部６１においても動き補償予測部５と同様に、動きベクトルは1/4画素精度まで表現でき、小数画素位置の画素値は、隣接する整数画素から補間して生成する。内挿補間画素を生成する際のＮの値および内装フィルタ係数を動き補償予測部と同様に色成分によって切り替えるようにしてもよいし、参照画像(色成分間予測参照画像)の色成分によって切り替えるようにしてもよい。
Ｎの値を増やすことにより、演算量の増大または１つの小数画素を生成するために必要な参照画素数が増えるため、メモリバンド幅の増大になるが、より正確に画素を予測することができるため、動き補償予測効率や相関利用予測効率が高まる。逆にＮの値を減らすことにより、演算量およびメモリバンド幅を抑えることができる。従って各色成分の持つ特徴に応じてＮの値および内装フィルタ係数を切り替えることで、回路規模を抑えて符号化効率を高めることができる。
別の実施の形態として、相関利用予測部６１においては、小数画素の精度を切り替えて、例えば1/2画素精度まで、あるいは整数画素のみにする、逆に1/8画素精度まで利用できるようにするなどしてもよい。 In the motion compensation prediction unit, the motion vector can be expressed up to 1/4 pixel accuracy. As shown in FIG. 37, when the reference pixel indicated by the motion vector is in the decimal pixel position, the adjacent N pixel (N ≧ 2). Then, an interpolated pixel is generated as a predicted value. As shown in FIG. 37, the pixel value (y ₃₀ ) at the decimal pixel position pointed to by the motion vector is obtained by the following equation with reference to eight adjacent integer pixel values. In the following formula (4), a _i is an interpolation filter coefficient.

Note that the value of N and the interpolation filter coefficient may be set to different values for each color component.
Similarly to the motion compensation prediction unit 5 in the correlation use prediction unit 61, the motion vector can be expressed up to 1/4 pixel precision, and the pixel value at the decimal pixel position is generated by interpolation from adjacent integer pixels. The value of N and the interior filter coefficient when generating the interpolation pixel may be switched according to the color component as in the motion compensation prediction unit, or may be switched according to the color component of the reference image (inter-color component prediction reference image). You may do it.
Increasing the value of N increases the amount of computation or the number of reference pixels required to generate one decimal pixel, which increases the memory bandwidth, but allows more accurate prediction of pixels. Therefore, motion compensation prediction efficiency and correlation utilization prediction efficiency are increased. Conversely, by reducing the value of N, the amount of computation and the memory bandwidth can be suppressed. Therefore, by switching the value of N and the interior filter coefficient according to the characteristics of each color component, it is possible to suppress the circuit scale and increase the encoding efficiency.
As another embodiment, the correlation use predicting unit 61 switches the precision of decimal pixels so that it can be used, for example, to 1/2 pixel precision, or to only integer pixels, and conversely to 1/8 pixel precision. You may do it.

Since the correlation use prediction unit 61 as described above can generate a prediction image with a small residual in the prediction process between color components, it is possible to improve the coding efficiency while keeping the circuit scale small.
In addition, a 4: 4: 4 format image can be compressed with high efficiency only by the luminance component encoding circuit.

Hereinafter, the processing content of the variable length encoding part 13 is demonstrated concretely.
As shown in FIG. 3, the variable length encoding unit 13 includes a transform coefficient variable length encoding unit 21 that performs variable length encoding on orthogonal transform coefficients that are compressed data output from the transform / quantization unit 7, and an input signal. A coding parameter variable length coding unit 22 that performs variable length coding on coding parameters such as a format difference, a coding mode, a prediction differential coding parameter including a transform block division flag, an intra prediction parameter / inter prediction parameter, and a block division information. The encoded data of the compressed data variable-length encoded by the transform coefficient variable-length encoding unit 21, the encoding parameter variable-length encoded by the encoding parameter variable-length encoding unit 22, and Are multiplexed to generate a bitstream.

A process of encoding the inter prediction parameter of the encoding parameter variable length encoding unit 22 will be described.
Inter prediction parameters output from the inter prediction unit 101 include a merge mode instruction flag, merge mode motion vector instruction information, prediction direction instruction information, reference image identification information, and prediction vector in units of prediction blocks (hereinafter referred to as PU). Parameters necessary for inter prediction such as instruction information and differential motion vector information are included.
The merge mode is a mode in which inter prediction parameters relating to a prediction block to be encoded (hereinafter, current PU) are substituted with inter prediction parameters of spatially adjacent surrounding PUs or PUs of reference images. Note that a reference image for referring to an inter prediction parameter is referred to as an inter prediction parameter reference image in order to distinguish it from a reference image for generating a prediction image. When the merge mode is selected (when the merge mode instruction flag is a value indicating that the current PU is in the merge mode), the spatially adjacent PUs in the surrounding or the inter prediction parameter reference image PU interface A merge candidate list is generated from the prediction parameters, an optimal inter prediction parameter is selected from the list as an inter prediction parameter to be substituted for the current PU, and its index (merge mode motion vector instruction information) is encoded. The upper limit of the number of inter prediction parameter candidates registered in the merge candidate list is determined for each picture or slice.

Next, a method for generating a merge candidate list will be described.
FIG. 34 shows pixel positions of spatially adjacent PUs among PUs registered in the merge candidate list. The inter prediction parameters of PUs at six pixel positions shown in FIG. 34 are registered in the merge candidate list. Note that among the adjacent PUs shown in FIG. 34, in the case of a PU that has not been encoded or a PU that has been encoded in the intra encoding mode, or in the case of an inter prediction parameter that is the same as a registered candidate, it is not registered as a candidate.
Next, PUs in the same spatial position as the current PU on the inter prediction parameter reference image are registered in the merge candidate list. Selectable inter prediction parameter reference images differ depending on the color components. In the case of the first color component, an inter prediction parameter reference image (temporal neighborhood reference image) is selected from the reference images (temporal direction prediction reference image) of the first color component as shown in FIG. Merge mode using only temporal direction prediction). A PU in the same spatial position as the current PU on the temporal neighborhood reference image is set as a merge candidate PU. When the inter prediction parameter of the merge candidate PU on the temporal neighborhood reference image is applied as the inter prediction parameter of the current PU, the motion vector of the merge candidate PU is the distance between the temporal neighborhood reference image and the reference image of the merge candidate PU ( The motion vector (mv _col ) of the merge candidate PU is scaled based on the POC difference value (td) and the distance between the current picture and the reference image of the current PU (POC difference value) (tb). The vector (mv _{merge_cand} ) is applied as the motion vector of the current PU (scaling with merge mode using only temporal prediction).

Next, the procedure for determining the merge candidate PU on the inter prediction parameter reference image in the case of a color component other than the first color component (for example, the second or third color component) will be described with reference to FIG.
In the case of the second or third color component that is a color component other than the first color component, whether the temporal vicinity reference image is used as the inter prediction parameter reference image as in the first color component (only temporal direction prediction) The inter prediction parameter reference image (inter-color component reference image) is selected from the reference images used for inter-color component prediction (merge mode using temporal direction prediction and inter-color component prediction). The PU of the first color component that is in the same spatial position as the current PU of the second or third color component that is a color component other than the first color component on the inter-color component reference image is set as a merge candidate PU. When the inter prediction parameter of the merge candidate PU on the inter-color component reference image is applied as the inter prediction parameter of the current PU, the motion vector of the merge candidate PU is the same as that of the inter-color component reference image and the reference image of the merge candidate PU. Based on the distance (POC difference value) (tf) and the distance between the current picture and the current PU reference image (POC difference value) (tb), the merge candidate PU motion vector (mv _col ) is scaled and scaled The motion vector (mv _{merge_cand} ) is applied as the motion vector of the current PU (with scaling in the merge mode using temporal direction prediction and inter-color component prediction). When tf and tb are equal, scaling is not necessary, and mv _col is applied as it is as mv _{merge_cand} (no scaling in merge mode using temporal direction prediction and inter-color component prediction). A reference image having the same POC as the reference image of the merge candidate PU may be selected as a reference image of the current PU from the temporal direction prediction reference images of the current PU so that scaling processing is not always necessary (time Always in the merge mode with direction prediction and inter-color component prediction without scaling).
Used when the merge mode is not selected (when the merge mode instruction flag is a value indicating that the PU is not in the merge mode) (a mode in which inter prediction is performed without using the merge mode). Inter prediction parameters (prediction direction instruction information, motion vector information, reference image identification information of the PU) are directly encoded. In motion vector coding, a motion vector candidate list is generated from motion vectors of spatially adjacent surrounding PUs or PUs of reference images, and an optimal prediction value candidate is selected from the list, and its index (prediction) (Vector instruction information) and a difference value (difference motion vector information) between the selected predicted value and the motion vector are encoded. The method for generating the motion vector candidate list is the same as the method for generating the merge candidate list.
Note that the inter prediction parameter reference image used for generating the merge candidate list or motion vector candidate list can be selected on a picture-by-picture basis, and the inter prediction parameter reference image instruction information is encoded with a picture or slice header.

Next, the operation of the transform coefficient variable length coding unit 21 will be described. Each transform block of the color component picture to be coded is arithmetically coded by the arithmetic coding process applied to the luminance component transform block of the transform coefficient variable length coding unit 21 of the first embodiment, and the block coded data Is output as
In addition, when the occurrence probability used for arithmetic coding of the transform coefficient parameter constituting the transform block such as significant_coeff_flag differs for each color component, a different context index value (context information) may be assigned for each color component. (Mode for switching context information for each color component).

Next, processing contents of the color moving image decoding apparatus will be described.
However, the second embodiment is the same as the first embodiment except that an inter prediction unit 111 is provided instead of the motion compensation unit 44, and the motion compensation unit 44 and the correlation use prediction unit 71 are provided in the inter prediction unit 111. .
If the variable length decoding unit 41 indicates that the prediction configuration flag is decoded from the encoded data and the prediction configuration flag indicates that the prediction encoding is performed between the color components of the 4: 4: 4 format, the access unit By decoding the delimiter, three YUV4: 0: 0 format images are recognized as one access unit that is a unit of access for display and the like.
Then, a picture (first color component picture) that is included in one access unit and includes only the first color component is decoded as a YUV4: 0: 0 format, and the decoded image of the first color component picture is motion compensated prediction. Using the decoded image of the first color component picture stored in the frame memory 49 and stored in the motion compensated prediction frame memory 49 as a reference image, color difference components other than the first color component (for example, U component and V component) ) Is assumed to be in the YUV4: 0: 0 format and is decoded.

The next first color component picture is decoded as a YUV4: 0: 0 format using the decoded image of the previous first color component picture stored in the motion compensated prediction frame memory 49 as a reference image. For the color components other than the color components (for example, the U component and the V component), the same color component picture as the decoding target stored in the motion compensated prediction frame memory 49 is decoded as in the motion compensated prediction of the first color component. A predicted image is generated using the image as a reference image (temporal direction prediction reference image), or a decoded image of the first color component having the same POC stored in the motion compensated prediction frame memory 49 is used as a reference image (color component) Inter-predicted reference image) to generate a predicted image. In addition, the process which produces | generates a prediction image using a time direction prediction reference image is performed in the motion compensation part 44, and the process which produces | generates a prediction image using the prediction reference image between color components is performed in the correlation utilization prediction part 71. FIG.
The contents of variable-length decoding processing for each color component picture when the prediction configuration flag indicates that the encoding is performed between the color components in the 4: 4: 4 format will be specifically described.

As shown in FIG. 6, the variable length decoding unit 41 includes a transform coefficient variable length decoding unit 51 that performs variable length decoding of orthogonal transform coefficients, which are compressed data, from encoded data multiplexed in a bit stream, and multiplexes the bit stream. Coding parameter variable length decoding unit for variable length decoding coding parameters such as input signal format information, coding mode, prediction differential coding parameter, intra prediction parameter / inter prediction parameter, block division information from coded coded data 52.
A process of decoding the inter prediction parameter of the encoding parameter variable length decoding unit 52 will be described.
Inter prediction parameters decoded by the variable length decoding unit 41 include a merge mode instruction flag, merge mode motion vector instruction information, prediction direction instruction information, reference image identification information (reference image index) in units of prediction blocks (PU). , Parameters necessary for inter prediction, such as prediction vector instruction information and differential motion vector information, are included.
First, information indicating the prediction reference destination of the inter prediction parameter used for generating the merge candidate list or the motion vector candidate list (inter prediction parameter reference image instruction information) in units of pictures or slices is variable-length decoded. The inter-prediction parameter reference image indication information is information for indicating a temporal vicinity reference image at the time of decoding the first color component picture, but the second or third color component picture which is a color component other than the first color component. At the time of decoding, it is information indicating either a temporal vicinity reference image or an inter-color component reference image.
Next, when the merge mode instruction flag variable-length decoded in units of PU indicates that the current PU is in the merge mode, the inter prediction parameter reference image specified based on the inter prediction parameter reference image instruction information Is used to generate a merge candidate list.

A method for generating a merge candidate list will be described.
FIG. 34 shows pixel positions of spatially adjacent PUs among PUs registered in the merge candidate list. The inter prediction parameters of PUs at six pixel positions shown in FIG. 34 are registered in the merge candidate list. Note that among the adjacent PUs shown in FIG. 34, the PU is not registered as a candidate in the case of a PU that has not been decoded or a PU that has been encoded in the intra encoding mode, or in the case of an inter prediction parameter that is the same as a registered candidate.
Next, PUs in the same spatial position as the current PU on the inter prediction parameter reference image are registered in the merge candidate list. As shown in FIG. 35, the inter prediction parameter reference image in the case of the first color component is a temporal neighborhood reference image (merge mode using only temporal direction prediction). A PU in the same spatial position as the current PU on the temporal neighborhood reference image is set as a merge candidate PU. When the inter prediction parameter of the merge candidate PU on the temporal neighborhood reference image is applied as the inter prediction parameter of the current PU, the motion vector of the merge candidate PU is the distance between the temporal neighborhood reference image and the reference image of the merge candidate PU ( The motion vector (mv _col ) of the merge candidate PU is scaled based on the POC difference value (td) and the distance between the current picture and the reference image of the current PU (POC difference value) (tb). The vector (mv _{merge_cand} ) is applied as the motion vector of the current PU (scaling with merge mode using only temporal prediction). A reference image having the same POC as the reference image of the merge candidate PU may be selected as a reference image of the current PU from the temporal direction prediction reference images of the current PU so that scaling processing is not always necessary (time (Merge mode with only direction prediction and always no scaling).

Next, the procedure for determining the merge candidate PU on the inter prediction parameter reference image in the case of the second or third color component that is a color component other than the first color component will be described with reference to FIG.
In the case of the second or third color component which is a color component other than the first color component, the inter prediction parameter reference image is a temporal neighborhood reference image (merge mode using only temporal direction prediction) or an inter-color component reference. One of images (merge mode using temporal direction prediction and inter-color component prediction). Even when the inter-color component reference image is used, the merge candidate PU is used as the PU of the first color component in the same space position as the current PU of the second or third color component which is a color component other than the first color component. And When the inter prediction parameter of the merge candidate PU on the inter-color component reference image is applied as the inter prediction parameter of the current PU, the motion vector of the merge candidate PU is the same as that of the inter-color component reference image and the reference image of the merge candidate PU. Based on the distance (POC difference value) (tf) and the distance between the current picture and the current PU reference image (POC difference value) (tb), the merge candidate PU motion vector (mv _col ) is scaled and scaled The motion vector (mv _{merge_cand} ) is applied as the motion vector of the current PU (with scaling in the merge mode using temporal direction prediction and inter-color component prediction). When tf and tb are equal, scaling is not necessary, and mv _col is applied as it is as mv _{merge_cand} (no scaling in merge mode using temporal direction prediction and inter-color component prediction). A reference image having the same POC as the reference image of the merge candidate PU may be selected as a reference image of the current PU from the temporal direction prediction reference images of the current PU so that scaling processing is not always necessary (time Always in the merge mode with direction prediction and inter-color component prediction without scaling).
Based on the merge mode motion vector instruction information, the merge candidate PU is selected from the generated merge candidate list, and the prediction direction instruction information to be applied to the current PU from the inter prediction parameters of the selected merge candidate PU, the motion vector, and A reference image index is derived.
If the merge mode instruction flag indicates that the current PU is not in merge mode (inter prediction mode without using merge mode), a motion vector candidate list is generated in the same manner as the merge candidate list. Based on the prediction vector instruction information subjected to variable length decoding, a motion vector prediction value of the current PU is derived from the motion vector candidate list. The motion vector of the current PU is derived based on the motion vector prediction value and the variable length decoded differential motion vector information.

Next, the operation of the transform coefficient variable length decoding unit 51 will be described. The encoded data of each transform block of the color component picture to be decoded is arithmetically decoded by the arithmetic decoding process applied to the encoded data of the luminance component transform block of the transform coefficient variable length decoding unit 51 of the first embodiment. .
Note that the occurrence probability used for arithmetic decoding of the transform coefficient parameter may be specified by referring to a different context index value (context information) for each color component for the transform coefficient parameter constituting the transform block, such as siginificant_coeff_flag. (Mode for switching context information for each color component).

  The correlation use prediction unit 71 in the third embodiment uses a block in the same position as the prediction target block in the reference image as a reference block, but the correlation use prediction unit 71 in the fourth embodiment uses variable length decoding. The difference is that the block in the reference image at the position indicated by the motion vector (included in the inter prediction parameter) decoded by the unit 41 is a reference block (the reference image index is not variable-length decoded, but the motion vector is variable-length Decoding mode). Note that the motion vector is not multiplexed in the bitstream, that is, the motion vector is not subjected to variable length decoding, and the prediction target block is always included in the reference image as in the correlation use prediction unit in the first embodiment. The block at the same position may be used as a reference block (a mode in which neither a motion vector nor a reference image index is variable-length decoded).

Here, when performing prediction between color components in the U component and the V component, which are color components other than the first color component, the variable length decoding unit 41 uses a motion compensation prediction mode or a correlation as a prediction mode for each block. The prediction method information indicating which of the usage prediction modes is applied is variable-length decoded.
When the prediction method information indicates that the motion compensation prediction mode is applied as the prediction mode, the image indicated by the reference image index from the temporal direction prediction reference images stored in the motion compensation prediction frame memory 49 is used as the reference image. The block at the position specified by the motion vector is used as a prediction image (the motion vector and the reference image index are included in the inter prediction parameter that has been variable-length decoded by the variable-length decoding unit).
When the prediction method information indicates that the correlation use prediction mode is applied as the prediction mode, a prediction image is generated by performing the above-described correlation use prediction process (the motion vector is variable length decoded by the variable length decoding unit). Included in the predicted inter prediction parameters.)

In the motion compensation unit 44, the motion vector can be expressed up to 1/4 pixel accuracy. As shown in FIG. 37, when the reference pixel indicated by the motion vector is in the decimal pixel position, the adjacent N pixels (N ≧ 2) Then, an interpolated pixel is generated as a predicted value. As shown in FIG. 37, the pixel value (y ₃₀ ) at the decimal pixel position pointed to by the motion vector is obtained by the following equation with reference to eight adjacent integer pixel values. In the following formula (4), a _i is an interpolation filter coefficient.
Note that the value of N and the interpolation filter coefficient may be set to different values for each color component.
Similarly to the motion compensation unit 44, the correlation use prediction unit 71 can express the motion vector to 1/4 pixel accuracy, and the pixel value at the decimal pixel position is generated by interpolation from adjacent integer pixels. The value of N and the interior filter coefficient when generating the interpolation pixel may be switched according to the color component as in the motion compensation prediction unit, or may be switched according to the color component of the reference image (inter-color component prediction reference image). You may do it.
Increasing the value of N increases the amount of computation or the number of reference pixels required to generate one decimal pixel, which increases the memory bandwidth, but allows more accurate prediction of pixels. Therefore, motion compensation prediction efficiency and correlation utilization prediction efficiency are increased. Conversely, by reducing the value of N, the amount of computation and the memory bandwidth can be suppressed. Therefore, by switching the value of N and the interior filter coefficient according to the characteristics of each color component, it is possible to suppress the circuit scale and increase the encoding efficiency.
As another embodiment, the correlation use prediction unit 71 switches the precision of the decimal pixel so that it can be used, for example, up to 1/2 pixel precision, or only integer pixels, and conversely, can be used up to 1/8 pixel precision. You may do it.
The color moving image decoding apparatus according to the fourth embodiment includes a motion compensation prediction mode and a correlation use prediction mode as prediction modes.
As a result, in the color moving image encoding device and color moving image decoding device according to the fourth embodiment, the encoded data compressed as described above can be suitably decoded only by the luminance component decoding circuit. The coding efficiency can be increased while the circuit scale is kept small. Note that the characteristic part of the fourth embodiment is a predicted image generation unit. If this predicted image generation unit is provided, the above-described effects of the color video encoding device and color video decoding device of the fourth embodiment are obtained. Can be obtained.

  Note that the operations of the encoding process and the decoding process other than the above-described operations are the same as those in the first embodiment, and thus the description thereof is omitted.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Encoding control part (encoding control means), 2 block division part (block division means), 3 changeover switch (prediction image generation part), 4 intra prediction part (prediction image generation part), 5 motion compensation prediction part (prediction) Image generation unit), 6 subtraction unit (difference image generation unit), 7 transform / quantization unit (image compression unit), 8 inverse quantization / inverse transform unit, 9 addition unit, 10 intra prediction memory, 11 loop filter unit , 12 motion compensated prediction frame memory, 13 variable length coding unit (variable length coding means), 21 transform coefficient variable length coding unit, 22 coding parameter variable length coding unit, 41 variable length decoding unit (variable length decoding) Means), 42 changeover switch (prediction image generation unit), 43 intra prediction unit (prediction image generation unit), 44 motion compensation unit (prediction image generation unit), 45 inverse quantization / inverse conversion unit (difference image generation unit) Stage), 46 addition unit (decoded image generation means), 47 intra prediction memory, 48 loop filter unit, 49 motion compensated prediction frame memory, 51 transform coefficient variable length decoding unit, 52 encoding parameter variable length decoding unit, 61 correlation Use prediction unit (prediction image generation unit), 62 correlation calculation unit, 63 correlation use prediction image generation unit, 71 correlation use prediction unit (prediction image generation unit), 72 correlation calculation unit, 73 correlation use prediction image generation unit, 81 correlation Use adaptive prediction unit (prediction image generation unit), 82 changeover switch, 83 intra prediction unit, 84 correlation use prediction unit, 91 correlation use adaptive prediction unit (prediction image generation unit), 92 changeover switch, 93 intra prediction unit, 94 correlation Usage prediction unit, 101 inter prediction unit, 102 changeover switch, 111 inter prediction unit, 112 changeover switch.

Claims (4)

A color moving image encoding apparatus that performs conversion processing with the same conversion block size in each color component of a color moving image,
For the first color component in the color moving image, a predicted image is generated by performing intra-frame predictive encoding when the signal format is 4: 0: 0 format, or other encoded A predictive image is generated by performing inter-frame predictive coding using a locally decoded image of the first color component included in a picture as a reference image, and color components other than the first color component in the color moving image For generating a prediction image by performing inter-frame predictive encoding using a locally decoded image of the same color component as the encoding target color component included in another encoded picture as a reference image, or Pixels of the locally decoded image of the first color component included in the same encoded picture and pixels for encoding contrast of color components other than the first color component to be encoded Predicting color components other than the first color component to be encoded by performing inter-frame predictive coding using the correlation parameter representing the correlation of the first color component and the locally decoded image of the first color component A color moving image encoding apparatus comprising a predicted image generation unit for generating an image. A color moving image decoding apparatus that performs conversion processing with the same conversion block size in each color component of a color moving image,
For the first color component in the color moving image, a predicted image is generated by performing intra-frame predictive decoding when the signal format is 4: 0: 0 format, or in other decoded pictures A prediction image is generated by performing inter-frame prediction decoding using the decoded image of the first color component included as a reference image, and decoding is performed for color components other than the first color component in the color moving image. A predicted image is generated by performing inter-frame predictive decoding using a decoded image having the same color component as the decoding target color component included in another completed picture as a reference image, or included in the same decoded picture A correlation parameter representing a correlation between a decoded image pixel of the first color component and a decoding target pixel of a color component other than the first color component to be decoded; A prediction image generation unit configured to generate a prediction image of a color component other than the first color component to be decoded by performing inter-frame prediction decoding using the decoded image of the first color component; A color video decoding device characterized by the above. A color moving image encoding method for performing conversion processing with the same conversion block size in each color component of a color moving image,
For the first color component in the color moving image, a predicted image is generated by performing intra-frame predictive encoding when the signal format is 4: 0: 0 format, or other encoded A predictive image is generated by performing inter-frame predictive coding using a locally decoded image of the first color component included in a picture as a reference image, and color components other than the first color component in the color moving image For generating a prediction image by performing inter-frame predictive encoding using a locally decoded image of the same color component as the encoding target color component included in another encoded picture as a reference image, or Pixels of the locally decoded image of the first color component included in the same encoded picture and pixels for encoding contrast of color components other than the first color component to be encoded Predicting color components other than the first color component to be encoded by performing inter-frame predictive coding using the correlation parameter representing the correlation of the first color component and the locally decoded image of the first color component A color moving image encoding method comprising a predicted image generation step of generating an image. A color moving image decoding method for performing conversion processing with the same conversion block size in each color component of a color moving image,
For the first color component in the color moving image, a predicted image is generated by performing intra-frame predictive decoding when the signal format is 4: 0: 0 format, or in other decoded pictures A prediction image is generated by performing inter-frame prediction decoding using the decoded image of the first color component included as a reference image, and decoding is performed for color components other than the first color component in the color moving image. A predicted image is generated by performing inter-frame predictive decoding using a decoded image having the same color component as the decoding target color component included in another completed picture as a reference image, or included in the same decoded picture A correlation parameter representing a correlation between a decoded image pixel of the first color component and a decoding target pixel of a color component other than the first color component to be decoded; A prediction image generation step of generating a prediction image of a color component other than the first color component to be decoded by performing inter-frame prediction decoding using the decoded image of the first color component; A color video decoding method characterized by the above.

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