JP6792996B2 - Encoding device, decoding device and program - Google Patents

Description

The present invention relates to a coding device, a decoding device and a program.

In the moving image (video) coding method represented by H.265 / HEVC (High Efficiency Video Coding), there are two types of inter-prediction using temporal correlation between frames and intra-prediction using spatial correlation within frames. It is configured to output a stream obtained by performing orthogonal conversion processing, loop filtering processing, and entropy coding processing after performing prediction while switching between types of prediction to generate a residual signal.

In intra-prediction in HEVC, a total of 35 types of intra-prediction modes such as Planar prediction, DC prediction, and direction prediction are prepared, and adjacent decoded reference pixels are set according to the intra-prediction mode determined by the encoder. It is configured to use to make intra-prediction and generate a prediction image. Hereinafter, unless otherwise specified, the description of "reference pixel" shall indicate a decoded reference pixel.

In HEVC, it is divided into a coding tree unit (CTU :: Coding Tree Unit), which is the largest unit block that encodes the original image of the frame unit that constitutes the moving image, and the coding processing is performed in raster order from the upper left. I will go. The CTU can be further divided into blocks called coding units (CUs) in a hierarchical manner, and the CTUs are divided according to the determination of the coding apparatus.

The coding device determines, for example, to perform coding processing in large block units in a flat area and in small block units in a region having a complicated texture, according to the pattern of the block to be coded. To do. In this way, by performing the coding process with a variable block size in the coding device, it is possible to reduce the amount of information required for transmission of flag information and orthogonal conversion coefficients required for each block.

However, when the texture area is present in a small part of the flat area and the block division is performed adaptively to the pattern, it is necessary to repeatedly perform the quadtree division. Block division is also performed for a flat area that does not need to be divided into blocks, which causes a problem that the amount of information required for transmitting flag information increases and the coding efficiency decreases.

For example, as shown in FIG. 10A, even if a part of the texture X exists inside the block, the quadtree division is repeated hierarchically, so that the flat area A on the right side inside the block is also a quadtree. It is necessary to divide, and the amount of information increases.

In order to solve such a problem, in Non-Patent Document 1, in addition to the hierarchical quadtree division of CU defined by HEVC, the binary tree division performed horizontally or vertically can be applied, and more pictures can be obtained. It is possible to divide according to.

For example, as shown in FIG. 10B, by applying the binary tree division, the block size in the flat region A becomes larger than that of the quadtree division, which is necessary for transmission of flag information, orthogonal conversion coefficient, and the like. It is possible to reduce the amount of information.

By the way, in the intra-prediction, as described above, the intra-prediction is applied according to the intra-prediction mode determined by the encoding device out of a total of 35 types of intra-prediction modes to generate a prediction image, and the applied intra-prediction mode is set. By transmitting such information to the decoding device side, the decoding device side generates a similar predicted image for decoding.

In HEVC, in order to reduce the amount of information required for transmission of the intra-prediction mode of the coded CU having the same texture as the adjacent CU, the intra-prediction mode applied to the surrounding CU is used as the intra-prediction mode candidate for MPM (Most). The Probe Mode) is generated and used to predict the intra prediction mode of the CU to be encoded.

In coding processing such as HEVC in which only quadtree division is applied, block division that is not originally necessary may occur as shown in FIG. 10, and it is increased by redundant block division by using MPM. It is possible to efficiently reduce the flag information that is stored.

Specifically, the MPM generates a list in a predetermined order based on an intra prediction mode to which a CU adjacent to the coded target CU is applied or a predetermined intra prediction mode.

Using the list of MPMs, flag information indicating whether or not the intra prediction mode applied by the encoded CU exists in the list of MPMs, and if such an intra prediction mode exists in the list of MPMs, It transmits an index indicating which intra-prediction mode to apply in the list of MPMs, and if such an intra-prediction mode does not exist in the list of MPMs, transmits the applied intra-prediction mode number to the decoding device side. ..

In addition to the MPM generation method defined by HEVC, there are MPM generation methods proposed in Non-Patent Document 2 and Non-Patent Document 3.

J. An, Y-W Chen, K. Zhang, H. Hung, Y-W Hung, S. Lei, "Block partitioning structure for next generation video coding", MPEG dock. m37524 and ITU-T SG16 Doc. COM16-C966, October 2015 JVET-C0055, "Probability based intra most probable mods list derivation" JVET-B1001, "Algorithm Description of Joint Exploration Test Model 2"

However, as in Non-Patent Document 1, when the binary tree division can be applied, the optimum block division for the pattern can be selected, so that the same intra prediction mode as the surrounding CU can be selected. It may be of low sex.

For example, as shown in FIGS. 11 (a) and 11 (b), in a texture region having a specific directionality, when block division is not performed as in FIG. 11 (a), a coding target is used. While the information related to the intra prediction mode and the orthogonal conversion coefficient of the CU is transmitted, when the bifurcation is performed in the vertical direction as shown in FIG. 11B, the intra prediction mode and the orthogonal conversion coefficient of each CU are transmitted. Since it is necessary to transmit the information related to the above and the amount of information to be transmitted increases, it is unlikely that the divided shape as shown in FIG. 11B is selected on the encoding device side.

In other words, when such a binary tree split shape is selected, it is highly likely that the left and right CUs have different intra prediction modes.

However, in Non-Patent Document 1, since the list of MPMs is determined without considering the tendency of selecting the intra-prediction mode in the binary tree division as described above, the efficiency of intra-prediction by the MPM in the intra-prediction mode is lowered. There is a problem of doing.

For the sake of simplification of the following description, two blocks having the same width and height generated by performing the binary tree division as shown in FIG. 11B (same before the final division). (Two blocks that existed in the block) are referred to as the same layer block.

In FIG. 12, CU1 and CU2 are referred to as the same layer CU, CU4 and CU5 are referred to as the same layer CU, and CU6 and CU7 are referred to as the same layer CU. However, in CU3, CU3 and CU4 or CU3 and CU5 are not called the same layer CU because the CU adjacent to the lower side is further divided into two trees and the block sizes are different. Further, even if the width and height are the same, such as CU2 and CU8 or CU5 and CU7, CUs that did not exist in the same CU before the final division are also called the same layer CU. Absent.

Therefore, the present invention has been made to solve the above-mentioned problems, and by not adding the intra prediction mode of the same layer CU of the coded target CU to the MPM list, it is possible to prevent a decrease in the efficiency of the intra prediction. It is an object of the present invention to provide an encoding device, a decoding device and a program capable of providing the same.

The first feature of the present invention is a coding device configured to divide an original image of a frame unit constituting a moving image into blocks and encode them, and is a candidate for an intra prediction mode of a block to be encoded. It is provided with a generation unit configured to generate the above and a coding unit configured to encode the intra prediction mode of the coded target block based on the intra prediction mode candidate. , The generator is a block having the same width and height as the coded block and existing in the same block as the coded block before being finally divided. The gist is that the intra prediction mode of the hierarchical block is configured not to be added to the intra prediction mode candidates.

The second feature of the present invention is a decoding device configured to divide the original image of each frame constituting the moving image into blocks and decode them, and generate an intra prediction mode candidate for the block to be encoded. It includes a generation unit configured to generate a prediction image based on the intra prediction mode of the coded target block extracted based on the intra prediction mode candidate, and an intra prediction unit configured to generate a prediction image. The block has the same width and height as the coded block, and was present in the same block as the coded block before the final division. The gist is that the intra-prediction mode of the same layer block is not added to the intra-prediction mode candidate.

A third feature of the present invention is a program for causing a computer to function as the coding device described in the first feature described above.

A fourth feature of the present invention is a program for making a computer function as a decoding device according to the second feature described above.

According to the present invention, there is provided a coding device, a decoding device and a program capable of preventing a decrease in the efficiency of intra prediction by not adding the intra prediction mode of the same layer CU of the coded target CU to the list of MPMs. be able to.

FIG. 1 is a diagram showing an example of a functional block of the coding apparatus 1 according to the first embodiment. FIG. 2 is a diagram showing an example of a method of generating a flag indicating the divided shape of the coded target CU by the block dividing unit 11 in the coding device 1 according to the first embodiment. FIG. 3 is a diagram showing an example of an MPM generation method by the MPM generation unit 12 of the coding apparatus 1 according to the first embodiment. FIG. 4 is a flowchart showing an example of the operation of the coding device 1 according to the first embodiment. FIG. 5 is a diagram showing an example of a functional block of the decoding device 3 according to the first embodiment. FIG. 6 is a flowchart showing an example of the operation of the decoding device 3 according to the first embodiment. FIG. 7 is a diagram showing an example of an MPM generation method by the MPM generation unit 12 of the coding apparatus 1 according to the second embodiment. FIG. 8 is a diagram for explaining an example of a method of generating MPM by the MPM generation unit 12 of the coding apparatus 1 according to the third embodiment. FIG. 9 is a diagram for explaining an example of a method of generating MPM by the MPM generation unit 12 of the coding apparatus 1 according to the third embodiment. FIG. 10 is a diagram for explaining modification 1. FIG. 11 is a diagram for explaining the prior art. FIG. 12 is a diagram for explaining the prior art.

(First Embodiment)
Hereinafter, the coding device 1 and the decoding device 3 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

Here, the coding device 1 and the decoding device 3 according to the present embodiment are configured to correspond to the intra prediction in the moving image coding method such as HEVC. The coding device 1 and the decoding device 3 according to the present embodiment are configured to be compatible with any moving image coding method as long as it is a moving image coding method that performs intra prediction.

The coding device 1 according to the present embodiment is configured to divide the original image of each frame constituting the moving image into coding target blocks and encode the original image. Hereinafter, in the present embodiment, a case where the frame-based original image constituting the moving image is divided into two quadtrees and encoded by the coding target CU will be described as an example, but the frame-based original image constituting the moving image will be described. It is also applicable to the case where the image is divided into quadtrees and encoded by the CU to be encoded.

As shown in FIG. 1, the coding apparatus 1 according to the present embodiment includes a block dividing unit 11, an MPM generating unit 12, an intra prediction unit 13, an orthogonal conversion / quantization unit 14, and an entropy coding unit 15. The inverse quantization / inverse conversion unit 16 and the memory 17 are provided.

The block division unit 11 divides a quadtree or a binary tree for each CU to be encoded, and sets a flag indicating the division shape of the CU to be encoded to the MPM generation unit 12, the intra prediction unit 13, and entropy encoding. It is configured to output to unit 15.

As an example of such division, the block division unit 11 may predefine the applicable block size and the maximum number of layers of the quadtree division, and the applicable block size and the maximum number of layers of the binary tree division.

Further, the block division unit 11 may be configured to first perform quadtree division and then perform binary tree division from an arbitrary layer in order to reduce processing in the coding device 1.

FIGS. 2 (a) to 2 (c) show an example of a method of generating a flag indicating the division shape of the case where the quadtree division is first performed and then the binary tree division is performed. Specifically, by performing the quadtree division shown in FIG. 2 (b) and then the binary tree division shown in FIG. 2 (c), the divided shape shown in FIG. 2 (a) can be realized. it can.

For example, as shown in FIG. 2B, in the flag indicating whether or not to perform the quadtree division, "0" indicates that the quadtree division is not performed for the corresponding CU, and "1". ”Indicates that the quadtree division is performed for the corresponding CU.

Further, as shown in FIG. 2C, for the CU that does not perform the quadtree division, a flag indicating whether or not to further divide the quadtree is generated. In such a flag, "0" indicates that the binary tree is not divided for the corresponding CU, "1" indicates that the binary tree is divided horizontally for the corresponding CU, and "2". ”Indicates that the binary tree is divided vertically with respect to the corresponding CU.

It should be noted that such flags may be configured to be collectively transmitted in units of CTUs, or may be configured to be transmitted together with an orthogonal conversion coefficient for each CU.

The MPM generation unit (generation unit) 12 encodes based on the division shape of the coding target CU divided by the block division unit 11 and the block division shape of the CU adjacent to the coding target CU stored in the memory 17. It is configured to generate a list of MPMs containing intra-prediction mode candidates for the target CU.

In HEVC, the MPM generation unit 12 is configured to generate a list of MPMs composed of three intra-prediction modes based on the intra-prediction modes of CUs adjacent to the left and upper sides of the CU to be encoded (). Specifically, refer to the H.265 standard ().

For example, the MPM generation unit 12 stores the intra prediction mode of the CU adjacent to the left side of the coded target CU in the 0th list of the MPM, and stores the intra prediction mode of the CU adjacent to the upper side of the coded target CU in the MPM list. It may be configured to store the Planar mode first and the Planar mode second in the list of MPMs. That is, the MPM makes it possible to reuse the intra prediction mode of the CU adjacent to the coded CU.

Here, among the CU blocks in which the binary tree is divided surrounded by the squares A to C in FIG. 2C, the CUs having the same division hierarchy and both flags being "0" are the same hierarchy CU ( Same level block). The CU with the flag f1 / f2 in FIG. 2C corresponds to the CU1 / CU2 in FIG. 2A, and the CU with the flag f3 / f4 in FIG. 2C corresponds to the CU1 / CU2 in FIG. 2A. , The CU corresponding to CU3 / CU4 in FIG. 2A and the flag f5 / f6 in FIG. 2C corresponds to CU5 / CU6 in FIG. 2A.

In the region having uniform characteristics as described above, the amount of flag generation information is reduced by performing the coding process with the block size as large as possible. Further, as shown in FIGS. 2A to 2C, as the number of division layers increases, the amount of information generated by the flag indicating the division shape increases. That is, if the two CUs generated by the binary tree division are not further divided, the characteristics such as the texture in these two CUs are likely to be different.

Therefore, the MPM generation unit 12 is configured not to add the intra prediction mode of the same layer CU of the coded block CU to the list of MPMs.

For example, the MPM generation unit 12 applies to the same layer CU when the coded object CU is a block divided into binary trees and the CU adjacent to the upper side or the left side of the coded object CU is the same layer CU. It is configured not to add the above intra prediction mode to the list of MPMs.

Further, for example, in FIG. 3, CU # T which is the CU to be encoded and CU # A adjacent to the left side of CU # T are the same layer CU, so that the MPM generation unit 12 predicts the intra of CU # A. Mode 15 is not added to the list of MPMs, but intra-prediction mode 8, intra-prediction mode 0 (Planar) and intra-prediction mode 1 (DC) of CU # B adjacent to the upper side of CU # T are added to the list of MPMs. It is configured as follows.

The above-mentioned MPM generation method is an example of applying the present invention to the MPM generation method based on the MPM generation method in HEVC. For example, the same applies to the MPM generation methods of Non-Patent Documents 2 and 3. Applicable.

The intra prediction unit 13 acquires the decoded reference pixels adjacent to the upper side and the left side of the coded target CU from the memory 17 according to the intra prediction mode determined by the coding device 1, and predetermines each of the intra prediction modes. It is configured to generate a prediction image by performing prediction processing.

The orthogonal conversion / quantization unit 14 performs orthogonal conversion processing and quantization processing on the difference between the predicted image and the original image generated by the intra prediction unit 13 so as to obtain a quantized orthogonal conversion coefficient. It is configured.

The entropy coding unit (coding unit) 15 is configured to perform entropy coding processing on the quantized orthogonal conversion coefficient and the intra prediction mode of the coded CU.

Here, the entropy coding unit 15 is configured to encode the intra prediction mode by a predetermined method using the list of MPMs generated by the MPM generation unit 12.

Specifically, the entropy coding unit 15 encodes the intra prediction mode number when the intra prediction mode of the coded target CU is included in the MPM list generated by the MPM generation unit 12. It is configured in.

On the other hand, the entropy coding unit 15 is configured to encode the intra prediction mode number when the intra prediction mode of the coded target CU is not included in the list of MPMs.

The inverse quantization unit / inverse orthogonal conversion unit 16 again performs inverse quantization processing and inverse orthogonal conversion processing on the quantized conversion coefficient generated by the orthogonal conversion / quantization unit 14 to generate a residual signal. It is configured to generate.

The memory 17 is configured to hold the decoded image of the CU to be encoded so as to be available as a reference image. Here, the decoded image is configured to be generated by adding the prediction image generated by the intra prediction unit 13 to the residual signal generated by the inverse quantization unit / inverse orthogonal conversion unit 16. There is.

Further, the memory 17 is configured to hold the divided shape and the intra prediction mode of the adjacent CU adjacent to the coded target CU.

FIG. 4 shows a flowchart for explaining an example of the operation of the coding apparatus 1 according to the present embodiment.

As shown in FIG. 4, in step S101, the coding apparatus 1 performs quadtree division and binary tree division for each coding target CU, and generates a flag indicating the division shape of the coding target block.

In step S102, the coding apparatus 1 selects an intra prediction mode candidate for the coding target CU based on the divided shape of the coding target CU, the divided shape of the adjacent CU adjacent to the coding target CU, and the intra prediction mode. Generate a list of MPMs to include.

In step S103, the coding device 1 is configured to generate a predicted image of the coded CU.

In step S104, the coding apparatus 1 generates a quantized orthogonal conversion coefficient by performing orthogonal conversion processing and quantization processing on the difference between the predicted image and the original image of the coded target CU.

In step S105, the coding apparatus 1 performs entropy coding processing on the quantized orthogonal conversion coefficient and the intra prediction mode of the coded CU.

Further, the decoding device 3 according to the present embodiment is configured to divide the original image of each frame constituting the moving image into CUs and decode it.

As shown in FIG. 5, the decoding device 3 according to the present embodiment includes an entropy decoding unit 31, an MPM generation unit 32, an intra prediction unit 33, an inverse quantization / inverse conversion unit 34, and a decoded image generation unit 35. The memory 36 and the intra prediction mode decoding unit 37 are provided.

The entropy decoding unit 31 performs entropy decoding processing on the stream output from the coding device 1 so as to decode the quantized orthogonal conversion coefficient and the like from the stream output from the coding device 1. It is configured.

The MPM generation unit 32 is based on the division shape of the CU of the coding target block, the division shape of the adjacent CU adjacent to the coding target CU, and the intra prediction mode, similarly to the MPM generation unit 12 of the coding device 1. Therefore, it is configured to generate a list of MPMs of the CU to be encoded.

Here, the MPM generation unit 32 is configured so as not to add the intra prediction mode of the same layer CU of the coding target CU to the list of MPMs, similarly to the MPM generation unit 12 of the coding device 1.

The intra prediction mode decoding unit 37 is configured to decode the intra prediction mode of the coded CU based on the list of MPMs generated by the MPM generation unit 32.

The intra prediction unit 33 is configured to generate a prediction image based on the intra prediction mode of the coded CU and the reference image held in the memory 36.

Here, the intra prediction unit 33 is configured to generate a prediction image based on the intra prediction mode of the coded target CU decoded by the intra prediction mode decoding unit 37 based on the list of MPMs.

Specifically, when the intra prediction unit 33 includes an index in the MPM list as information indicating the intra prediction mode of the coded target CU in the stream output from the coding device 1, the intra prediction unit 33 of the MPM It is configured to generate a prediction image using the intra prediction mode corresponding to the index in the list.

The inverse quantization / inverse conversion unit 34 performs an inverse quantization process and an inverse conversion process (for example, an inverse orthogonal conversion process) on the quantized conversion coefficient output by the entropy decoding unit 31 to obtain a residual. It is configured to generate a signal.

The decoded image generation unit 35 is configured to generate a decoded image by adding the predicted image generated by the intra prediction unit 33 and the residual signal generated by the inverse quantization / inverse conversion unit 34.

The memory 36 is configured to hold the decoded image generated by the decoded image generation unit 35 so as to be available as a reference image for intra prediction.

FIG. 6 shows a flowchart for explaining an example of the operation of the decoding device 3 according to the present embodiment.

As shown in FIG. 6, in step S201, the decoding device 3 is quantized from the stream output from the coding device 1 by performing an entropy decoding process on the stream output from the coding device 1. Decode the orthogonal conversion coefficient, etc.

In step S202, the decoding device 3 generates a list of MPMs of the coded target CU based on the CU of the coded target block and the division shape and the intra prediction mode of the adjacent CU adjacent to the coded target CU.

In step S203, the decoding device 3 decodes the intra prediction mode of the coded target CU based on the list of MPMs, and generates a predicted image based on the intra prediction mode of the coded target CU and the held reference image. To do.

In step S204, the decoding device 3 generates a residual signal by performing an inverse quantization process and an inverse conversion process (for example, an inverse orthogonal conversion process) on the quantized conversion coefficient.

In step S205, the decoding device 3 generates a decoded image by adding the predicted image and the residual signal.

According to the coding device 1 and the decoding device 3 according to the present embodiment, the prediction efficiency of the intra prediction mode is improved by generating a list of MPMs according to the divided shapes of the CUs to be coded, and the coding efficiency is improved. Can be improved.

(Second Embodiment)
Hereinafter, with reference to FIG. 7, the coding device 1 and the decoding device 3 according to the second embodiment of the present invention are different from the coding device 1 and the decoding device 3 according to the first embodiment described above. This will be explained focusing on.

In the coding apparatus 1 according to the present embodiment, the MPM generation unit 12 is the MPM of the coding target CU even in the intra prediction mode of the adjacent CU (non-same layer CU) which is not the same layer CU of the coding target CU. If it is the same as the intra prediction mode determined not to be added to the list of the above, the intra prediction mode of the adjacent CU that is not the same layer CU is not added to the list of MPMs of the coded CU.

That is, in the coding device 1 of the first embodiment, the MPM generation unit 12 is configured so as not to add the intra prediction mode of the same layer CU of the coding target CU to the list of MPMs. Therefore, in FIG. 7, the MPM generation unit 12 applies the same intra prediction mode 15 as the same layer CU (CU # A) in the adjacent CU (CU # B) which is not the same layer CU of the coded target CU. In some cases, such intra-prediction mode 15 is configured to be added to the list of MPMs.

On the other hand, in the coding device 1 of the present embodiment, the MPM generation unit 12 saves the intra prediction mode of the same layer CU of the coded target CU as the MPM list addition prohibition mode, and is not another same layer CU. When the intra prediction mode of the adjacent CU (non-same layer CU) is the same as the MPM list addition prohibition mode, such an intra prediction mode is not added to the MPM list.

For example, in the example of FIG. 7, the MPM generation unit 12 saves the intra prediction mode 15 of the CU # A adjacent to the left side of the same layer CU of the CU # T to be encoded as the MPM list addition prohibition mode. It is configured as follows.

In such a case, in the MPM generation unit 12, the intra prediction mode 15 of the CU # B which is not the same layer CU adjacent to the upper side of the CU # T is the same as the intra prediction mode 15 stored as the MPM list addition prohibition mode. Therefore, the intra prediction mode 15 of CU # B is not added to the list of MPMs, but the intra prediction modes 0, 1, and 26 are added to the list of MPMs.

Such an example is a case where the present invention is applied based on the MPM generation method of HEVC, and any generation method if the order of storing in the MPM list is made common in the coding device 1 and the decoding device 3 in advance. May be used.

In the decoding device 3 according to the present embodiment, the MPM generation unit 32 is an intra prediction mode of an adjacent CU (non-same layer CU) that is not the same layer CU of the coded target CU, like the MPM generation unit 12. However, if it is the same as the intra prediction mode determined not to be added to the list of MPMs of the CU to be encoded, the intra prediction mode of the adjacent CU that is not the same layer CU is added to the list of MPMs of the CU to be encoded. It is configured not to add.

(Third Embodiment)
Hereinafter, with reference to FIGS. 8 and 9, the coding device 1 and the decoding device 3 according to the third embodiment of the present invention will be referred to as the coding device 1 and the decoding device 3 according to the first embodiment described above. The explanation will be given focusing on the differences between.

In the coding device 1 according to the present embodiment, the MPM generation unit 12 uses a reference pixel located on the upper side in the intra prediction process applied to the same layer CU adjacent to the upper side of the coded target CU. In some cases, it is configured to be added to the list of MPMs even in the intra prediction mode of the same layer CU.

Similarly, in the coding device 1 according to the present embodiment, the MPM generation unit 12 uses the reference pixel located on the left side in the intra prediction process applied to the same layer CU adjacent to the left side of the coded target CU. If so, it is configured to be added to the MPM list even in the intra-prediction mode of the same layer CU.

In the intra prediction process, the intra prediction unit 13 is configured to generate a prediction image using reference pixels located on the left side or the upper side of the coded target CU acquired from the memory 17.

Of the intra prediction modes in HEVC, intra prediction modes 0, 1, 10 to 26 are predictions using reference pixels located on the left and upper sides of the CU to be encoded, and intra prediction modes 2 to 9 are encoded. It is a prediction that uses only the reference pixel located on the left side of the target CU, and the intra prediction modes 27 to 34 are predictions that use only the reference pixel located on the upper side of the coded target CU.

Here, attention is paid to a prediction image when the same intra prediction mode as that of an adjacent CU of the same layer is applied in the CU to be encoded.

When the reference pixels located on the upper side and the left side of the coded target CU are used in the intra prediction process, a part of the decoded image of the CU adjacent to the upper side of the coded target CU is used as the reference pixel to be coded. Since the predicted image of CU is generated, as shown in FIGS. 8 (a) to 8 (c), the predicted image (see FIG. 8 (a)) and the block generated when the block division is not performed. The predicted images (see FIGS. 8 (b) and 8 (c)) generated when the division is performed are different.

On the other hand, as shown in FIGS. 9A to 9C, when only the reference pixel located on the left side of the coding target CU is used in the intra prediction processing, it is adjacent to the upper side of the coding target CU. Since the decoded image of the same layer CU is not used to generate the predicted image of the CU to be encoded, there is no difference in the predicted image depending on the presence or absence of block division.

Therefore, in the coding apparatus 1 according to the present embodiment, as shown in FIG. 9, the MPM generation unit 12 is in the case of being horizontally divided into binary trees, and is in the same layer adjacent to the upper side of the coding target CU. When the reference pixel on the upper side of the coded target CU is not used in the intra prediction process by the intra prediction mode of the CU, the intra prediction mode of the same layer CU is not added to the list of MPMs.

On the other hand, as shown in FIG. 8C, the MPM generation unit 12 is a case where the binary tree is divided horizontally, and the intra is in the intra prediction mode of the same layer CU adjacent to the upper side of the coded CU. When the upper and left reference pixels are used in the prediction process, the intra prediction mode of the same layer CU is configured to be added to the list of MPMs.

Further, in the MPM generation unit 12, the reference pixel on the left side is used in the intra prediction process in the intra prediction mode of the same layer CU adjacent to the left side of the coded target CU when the MPM generation unit 12 is vertically divided into two trees. If not, the intra-prediction mode of the same layer CU is configured not to be added to the list of MPMs.

On the other hand, in the MPM generation unit 12, the upper and left reference pixels are in the case where the binary tree is vertically divided and in the intra prediction processing by the intra prediction mode of the same layer CU adjacent to the left side of the coded CU. When used, it is configured to add the intra-prediction mode of such a hierarchy CU to the list of MPMs.

In the decoding device 3 according to the present embodiment, the MPM generation unit 32, like the MPM generation unit 12, is placed on the upper side in the intra prediction process applied to the same layer CU adjacent to the upper side of the coded target CU. When the position reference pixel is used, it is configured to be added to the MPM list even in the intra prediction mode of the same layer CU.

Similarly, in the decoding device 3 according to the present embodiment, the MPM generation unit 32, like the MPM generation unit 12, is on the left side in the intra prediction process applied to the same layer CU adjacent to the left side of the coded target CU. When the reference pixel located in is used, it is configured to be added to the MPM list even in the intra prediction mode of the same layer CU.

(Other embodiments)
As mentioned above, the invention has been described by the embodiments described above, but the statements and drawings that form part of the disclosure in such embodiments should not be understood as limiting the invention. Such disclosure will reveal to those skilled in the art various alternative embodiments, examples and operational techniques.

Further, although not particularly mentioned in the above-described embodiment, a program for causing a computer to execute each process performed by the above-mentioned encoding device 1 and decoding device 3 may be provided. The program may also be recorded on a computer-readable medium. Computer-readable media can be used to install such programs on computers. Here, the computer-readable medium on which such a program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

Alternatively, even if a chip composed of a memory for storing a program for realizing at least a part of the functions in the encoding device 1 and the decoding device 3 described above and a processor for executing the program stored in the memory is provided. Good.

1 ... Encoding device 11 ... Block dividing unit 12 ... MPM generation unit 13 ... Intra prediction unit 14 ... Orthogonal conversion / quantization unit 15 ... Entropy coding unit 16 ... Inverse quantization / inverse conversion unit 17 ... Memory 3 ... Decoding device 31 ... Entropy decoding unit 32 ... MPM generation unit 33 ... Intra prediction unit 34 ... Inverse quantization / inverse conversion unit 35 ... Decoded image generation unit 36 ... Memory

Claims (12)

A coding device configured to divide the original image of each frame constituting a moving image into blocks and encode them.
A generator configured to generate intra-prediction mode candidates for the coded block,
It is provided with a coding unit configured to encode the intra prediction mode of the coded target block based on the intra prediction mode candidate.
The generation unit has the same width and height as the coded block, and is a block that was present in the same block as the coded block when it was finally divided. An encoding device characterized in that the intra prediction mode of a block is not added to the intra prediction mode candidate. When the intra prediction mode of the non-same layer block adjacent to the coded target block instead of the same layer block is the same as the intra prediction mode determined not to be added to the intra prediction mode candidate. The coding apparatus according to claim 1, wherein the intra prediction mode of the non-same layer block is not added to the intra prediction mode candidate. When the reference pixel located on the upper side is used in the intra prediction process applied to the same layer block located on the upper side of the coded target block, the generation unit is the intra of the same layer block. The coding apparatus according to claim 1 or 2, wherein the coding apparatus is configured to be added to the intra prediction mode candidate even in the prediction mode. When the reference pixel located on the left side is used in the intra prediction process applied to the same layer block located on the left side of the coded target block, the generation unit is the intra of the same layer block. The coding apparatus according to any one of claims 1 to 3, wherein the coding apparatus is configured to be added to the intra prediction mode candidate even in the prediction mode. It is a decoding device that is configured to divide the original image of each frame that constitutes a moving image into blocks and decode it.
A generator configured to generate intra-prediction mode candidates for the coded block,
It includes an intra prediction unit configured to generate a prediction image based on the intra prediction mode of the coded block extracted based on the intra prediction mode candidate.
The generation unit has the same width and height as the coded block, and is a block that was present in the same block as the coded block when it was finally divided. A decoding device characterized in that the intra prediction mode of a block is not added to the intra prediction mode candidate. When the intra-prediction mode of the non-same-layer block adjacent to the coded target block instead of the same-layer block is the same as the intra-prediction mode determined not to be added to the intra-prediction mode candidate. The decoding device according to claim 5, wherein the intra prediction mode of the non-same layer block is not added to the intra prediction mode candidate. When the reference pixel located on the upper side is used in the intra prediction process applied to the same layer block located on the upper side of the coded target block, the generation unit is the intra of the same layer block. The decoding device according to claim 5 or 6, wherein the decoding device is configured to be added to the intra prediction mode candidate even in the prediction mode. When the reference pixel located on the left side is used in the intra prediction process applied to the same layer block located on the left side of the coded target block, the generation unit is the intra of the same layer block. The decoding device according to any one of claims 5 to 7, wherein the decoding device is configured to be added to the intra prediction mode candidate even in the prediction mode. It is configured to divide the original image of each frame that composes the moving image into blocks and encode it.
It is a coding device that is
A generator configured to generate intra-prediction mode candidates for the block to be encoded
When,
Based on the intra prediction mode candidate, the intra prediction mode of the coded block is
It is provided with a coding unit configured to encode the code.
When the generator is finally divided, it is placed in the same block as the coded block.
The intra prediction mode of the same layer block, which is a block that existed, is set to the intra prediction mode.
An encoding device characterized in that it is configured not to be added to a card candidate. It is configured to divide the original image of each frame that composes the moving image into blocks and decode it.
Decryptor
A generator configured to generate intra-prediction mode candidates for the block to be encoded
When,
The intra prediction of the coded block extracted based on the intra prediction mode candidate.
It includes an intra-prediction unit configured to generate a prediction image based on the measurement mode.
And
When the generator is finally divided, it is placed in the same block as the coded block.
The intra prediction mode of the same layer block, which is a block that existed, is set to the intra prediction mode.
A decoding device characterized in that it is configured not to be added to a card candidate. A program for causing a computer to function as the encoding device according to any one of claims 1 to 4 , and 9 . A program for operating a computer as a decoding device according to any one of claims 5 to 8 and 10 .

Images