Methods and apparatuses for coding and decoding depth map

• US 10,666,977 B2
• Filed: 10/09/2015
• Issued: 05/26/2020
• Est. Priority Date: 04/12/2013
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Zheng, Xiaozhen
• Primary Examiner(s): Jebari, Mohammed
• Application Number:
  US14/880,094
• Publication Number:
  US 20160037185A1
• Time in Patent Office: 1,691 Days
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/597 specially adapted for multi-view video sequence encoding
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

Embodiments of the present invention provide methods and devices for coding and decoding a depth map, including: determining to perform simplified depth coding (SDC) decoding according to a flag of an SDC mode; determining a size of an image block and a maximum prediction size; determining an intra-frame prediction mode; in a case in which the size of the image block is greater than the maximum prediction size, splitting the image block to obtain N split image blocks; and performing the SDC decoding on the N split image blocks by using the intra-frame prediction mode. In this way, processing efficiency of coding and decoding a depth map can be improved.

Claims

1. A method for simplified depth decoding, the method comprising:

obtaining a flag of simplified depth coding (SDC), wherein a value of the flag indicates that SDC decoding is used for an image block;

determining a size of the image block and a maximum prediction size, wherein the image block is a transform block, wherein the size of the image block is a size of the transform block, and wherein the maximum prediction size is a maximum transform size;

determining an intra prediction mode of the image block;

comparing the size of the image block with the maximum prediction size;

splitting the image block to obtain N split image blocks when the size of the image block is greater than the maximum prediction size, wherein a size of each of the N split image blocks is the same as the maximum prediction size and the N split image blocks are all transform blocks;

obtaining a residual by means of decoding when performing the SDC decoding on an i^th split image block of the N split image blocks;

obtaining prediction data of the i^th split image block using the intra prediction mode that is used when the SDC is performed on the image block;

determining an average value of the prediction data of the i^th split image block based on a plurality of pixel values in the prediction data of the i^th split image block and a number of pixels in the i^th split image block; and

determining a reconstruction value of the i^th split image block according to the average value of the prediction data of the i^th split image block and the residual, so as to complete performing the SDC decoding on the i^th split image block.

2. The method according to claim 1, wherein the intra prediction mode used when the SDC is performed on the image block is a depth modeling mode (DMM) or a planar mode or a direct current mode.

3. The method according to claim 1, wherein splitting the image block to obtain the N split image blocks comprises:

splitting the image block to obtain split image blocks according to the size of the image block and the maximum prediction size, wherein when a size of the split image blocks is the same as the maximum prediction size, the N split image blocks are obtained, and wherein when a size of the split image blocks is greater than the maximum prediction size, the split image blocks are further split until the size of the split image blocks is the same as the maximum prediction size, and the N split image blocks are obtained.

4. The method according to claim 1, wherein determining the average value of the prediction data of the i^th split image block based on the plurality of pixel values in the prediction data of the i^th split image block and the number of pixels in the i^th split image block comprises determining the average value of the prediction data of the i^th split image block of the N split image blocks by using the following formula:

PV_i=Σ

PPix_i[x,y]/sumOfPPix,

wherein PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, PPix_i[x,y] is a pixel value in prediction data whose coordinates are [x,y] in the i^th split image block, and sumOfPPix is the number of pixels in the i^th split image block.

5. The method according to claim 1, wherein determining the reconstruction value of the i^th split image block according to the average value of the prediction data of the i^th split image block and the residual, so as to complete performing the SDC decoding on the i^th split image block comprises determining the reconstruction value of the i^th split image block of the N split image blocks by using the following formula:

R_i=PV_i+S_i,

wherein R_i is a reconstruction value of the i^th split image block among the N split image blocks, PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, and S_i is a residual of the i^th split image block among the N split image blocks.

6. A method for simplified depth coding (SDC), the method comprising:

determining a size of an image block and a maximum prediction size, wherein the image block is a transform block, wherein the size of the image block is a size of the transform block, and wherein the maximum prediction size is a maximum transform size;

determining an intra prediction mode;

comparing the size of the image block with the maximum prediction size;

splitting the image block to obtain N split image blocks when the size of the image block is greater than the maximum prediction size, wherein a size of the N split image blocks is the same as the maximum prediction size, and wherein the N split image blocks are all transform blocks; and

determining prediction data of the i^th split image block of the N split image blocks by using the intra prediction mode;

determining an average value of the prediction data of the i^th split image block based on a plurality of pixel values in the prediction data of the i^th split image block and a number of pixels in the i^th split image block;

determining an average value of raw data of the i^th split image block of the N split image blocks;

determining a residual of the i^th split image block according to the average value of the prediction data of the i^th split image block and the average value of the raw data of the i^th split image block; and

coding the residual of the i^th split image block, so as to complete performing SDC on the i^th split image block.

7. The method according to claim 6, wherein the intra prediction mode is a depth modeling mode (DMM) or a planar mode or a direct current mode.

8. The method according to claim 6, wherein splitting the image block to obtain N split image blocks comprises splitting the image block to obtain split image blocks according to the size of the image block and the maximum prediction size, wherein when a size of the split image blocks is the same as the maximum prediction size, the N split image blocks are obtained, and when a size of the split image blocks is greater than the maximum prediction size, the method comprises continuing to split the split image blocks until the size of the split image blocks is the same as the maximum prediction size, and the N split image blocks are obtained.

9. The method according to claim 6, wherein determining the average value of the prediction data of the i^th split image block based on the plurality of pixel values in the prediction data of the i^th split image block and the number of pixels in the i^th split image block, comprises determining the average value of the prediction data of the i^th split image block of the N split image blocks by using the following formula:

PV_i=Σ

PPix_i[x,y]/sumOfPPix,

wherein PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, PPix_i[x,y] is a pixel value in prediction data whose coordinates are [x,y] in the i^th split image block, and sumOfPPix is the number of pixels in the i^th split image block.

10. The method according to claim 6, wherein determining the average value of raw data of the i^th split image block of the N split image blocks comprises determining the average value of the raw data of the i^th split image block of the N split image blocks by using the following formula:

BV_i=Σ

BPix_i[x,y]/sumOfBPix,

wherein BV_i is an average value of raw data of the i^th split image block among the N split image blocks, BPix_i[x,y] is a pixel value in raw data whose coordinates are [x,y] in the i^th split image block, and sumOfBPix is the number of pixels in the i^th split image block.

11. The method according to claim 6, wherein determining the residual of the i^th split image block according to the average value of the prediction data of the i^th split image block and the average value of the raw data of the i^th split image block comprises determining the residual of the i^th split image block of the N split image blocks by using the following formula:

S_i=PV_i−

BV_i,

wherein S_i is a residual of the i^th split image block among the N split image blocks, PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, and BV_i is an average value of raw data of the i^th split image block among the N split image blocks.

12. The method according to claim 6, wherein the method further comprises performing SDC on the image block by using the intra prediction mode when the size of the image block is less than or equal to the maximum prediction size.

13. A method for simplified depth decoding, the method comprising:

determining a size of an image block and a maximum prediction size;

when the size of the image block is greater than the maximum prediction size, determining that a signaling bit has N bits, and determining, according to the signaling bits, a first intra prediction mode that is used when simplified depth coding (SDC) is performed on the image block, wherein the first intra prediction mode is one mode among a first set of modes; and

when the size of the image block is less than or equal to the maximum prediction size, determining that signaling bits have M bits, and determining, according to the signaling bits, a second intra prediction mode that is used when the SDC is performed on the image block, wherein the second intra prediction mode is one mode among a second set of modes, wherein a depth modeling mode (DMM) is included in the second set of modes but not included in the first set of modes, and wherein a value of M is greater than that of N.

14. The method according to claim 13, wherein the second intra prediction mode is a direct current mode, a planar mode, or the DMM.

15. A simplified depth coding method, the method comprising:

determining a size of an image block and a maximum prediction size;

selecting a first intra prediction mode;

when the size of the image block is greater than the maximum prediction size and when simplified depth coding (SDC) is performed on the image block, determining that N bits are used as a signaling bit that identifies the first intra prediction mode, wherein the first intra prediction mode is one mode among a first set of modes; and

when the size of the image block is less than or equal to the maximum prediction size and when the SDC is performed on the image block, determining that M bits are used as signaling bits that identify a second intra prediction mode, wherein the second intra prediction mode is one mode among a second set of modes, wherein a depth modeling mode (DMM) is included in the second set of modes but not included in the first set of modes, and wherein a value of M is greater than that of N.

16. The method according to claim 15, wherein the second intra prediction mode is a direct current mode or a planar mode or the DMM.

17. A decoding apparatus for simplified depth decoding, the decoding apparatus comprising:

a memory storing instructions; and

a processor configured to execute the instructions such that when executed, the instructions cause the processor to be configured to;

determine, according to a flag of simplified depth coding (SDC), to use SDC decoding, determine a size of an image block and a maximum prediction size, wherein the image block is a transform block, the size of the image block is a size of the transform block, and the maximum prediction size is a maximum transform size;

determine an intra prediction mode that is used when SDC is performed on the image block, compare the size of the image block with the maximum prediction size;

split the image block to obtain N split image blocks when the size of the image block is greater than the maximum prediction size, wherein a size of the N split image blocks is the same as the maximum prediction size and the N split image blocks are all transform blocks;

obtain a residual by means of decoding when performing the SDC decoding on an i^th split image block of the N split image blocks;

obtain prediction data of the i^th split image block by using the intra prediction mode that is used when the SDC is performed on the image block;

determine an average value of the prediction data of the i^th split image block based on a plurality of pixel values in the prediction data of the i^th split image block and a number of pixels in the i^th split image block; and

determine a reconstruction value of the i^th split image block according to the average value of the prediction data of the i^th split image block and the residual, so as to complete performing the SDC decoding on the i^th split image block.

18. The decoding apparatus according to claim 17, wherein the instructions further cause the processor to be configured to:

split the image block to obtain split image blocks according to the size of the image block and the maximum prediction size, wherein when a size of the split image blocks is the same as the maximum prediction size, the N split image blocks are obtained; and

when a size of the split image blocks is greater than the maximum prediction size, continue to split the split image blocks until the size of the split image blocks is the same as the maximum prediction size, and the N split image blocks are obtained.

19. The decoding apparatus according to claim 17, wherein the instructions further cause the processor to be configured to:

determine the average value of the prediction data of the i^th split image block of the N split image blocks by using the following formula;

PV_i=Σ

PPix_i[x,y]/sumOfPPix,

wherein PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, PPix_i[x,y] is a pixel value in prediction data whose coordinates are [x,y] in the i^th split image block, and sumOfPPix is the number of pixels in the i^th split image block.

20. The decoding apparatus according to claim 17, wherein the instructions further cause the processor to be configured to determine the reconstruction value of the i^th split image block of the N split image blocks by using the following formula:

R_i=PV_i+S_i,

wherein R_i is a reconstruction value of the i^th split image block among the N split image blocks, PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, and S_i is a residual of the i^th split image block among the N split image blocks.

21. A coding apparatus for simplified depth coding (SDC), the coding apparatus comprising:

a memory storing instructions; and

a processor configured to execute the instructions such that when executed, the instructions cause the processor to be configured to;

determine a size of an image block and a maximum prediction size, wherein the image block is a transform block, the size of the image block is a size of the transform block, and the maximum prediction size is a maximum transform size;

determine an intra prediction mode;

compare the size of the image block with the maximum prediction size;

split the image block to obtain N split image blocks when the size of the image block is greater than the maximum prediction size, wherein a size of the N split image blocks is the same as the maximum prediction size, and wherein the N split image blocks are all transform blocks;

determine prediction data of an i^th split image block of the N split image blocks by using the intra prediction mode;

determine an average value of the prediction data of the i^th split image block based on a plurality of pixel values in the prediction data of the i^th split image block and a number of pixels in the i^th split image block;

determine an average value of raw data of the i^th split image block of the N split image blocks;

determine a residual of the i^th split image block according to the average value of the prediction data of the i^th split image block and the average value of the raw data of the i^th split image block; and

code the residual of the i^th split image block, so as to complete performing SDC on the i^th split image block.

22. The coding apparatus according to claim 21, wherein the instructions further cause the processor to be configured to:

split the image block to obtain split image blocks according to the size of the image block and the maximum prediction size, wherein when a size of the split image blocks is the same as the maximum prediction size, the N split image blocks are obtained; and

when a size of the split image blocks is greater than the maximum prediction size, continue to split the split image blocks until the size of the split image blocks is the same as the maximum prediction size, and the N split image blocks are obtained.

23. The coding apparatus according to claim 21, wherein the instructions further cause the processor to be configured to:

determine the average value of the prediction data of the i^th split image block of the N split image blocks by using the following formula;

PV_i=Σ

PPix_i[x,y]/sumOfPPix,

wherein PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, PPix_i[x,y] is a pixel value in prediction data whose coordinates are [x,y] in the i^th split image block, and sumOfPPix is the number of pixels in the i^th split image block.

24. The coding apparatus according to claim 21, wherein the instructions further cause the processor to be configured to determine the average value of the raw data of the i^th split image block of the N split image blocks by using the following formula:

BV_i=Σ

BPix_i[x,y]/sumOfBPix,

wherein BV_i is an average value of raw data of the i^th split image block among the N split image blocks, BPix_i[x,y] is a pixel value in raw data whose coordinates are [x,y] n the i^th split image block, and sumOfBPix is the number of pixels in the i^th split image block.

25. The coding apparatus according to claim 21, wherein the instructions further cause the processor to be configured to determine the residual of the i^th split image block of the N split image blocks by using the following formula:

S_i=PV_i−

BV_i,

wherein S_i is a residual of the i^th split block among the N split image blocks, PV_i is an average value of prediction data of the i^th split image block among the N split image blocks, and BV_i is an average value of raw data of the i^th split image block among the N split image blocks.

26. The coding apparatus according to claim 21, wherein the instructions further cause the processor to be configured to perform SDC on the image block according to the intra prediction mode when the size of the image block is less than or equal to the maximum prediction size.