METHODS AND APPARATUSES FOR CODING AND DECODING DEPTH MAP

• US 20150312592A1
• Filed: 07/09/2015
• Published: 10/29/2015
• Est. Priority Date: 01/10/2013
• 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
• Granted Patent: US 10,034,021 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/597 specially adapted for multi-view video sequence encoding

Abstract

Embodiments of the present invention provide methods and apparatuses for coding and decoding a depth map. The coding method includes: obtaining prediction data corresponding to a current image block of the depth map, obtaining a predicted pixel value from the prediction data according to a preset step, and calculating a first average value of the prediction data according to the predicted pixel value, where the preset step is a positive integer except 1; obtaining a residual of the current image block according to the first average value of the prediction data and a pixel value of a pixel of the current image block; and coding the residual of the current image block. In this way, coding and decoding efficiency can be improved.

Claims

1. A method for coding a depth map, comprising:

obtaining prediction data of a current image block of the depth map, obtaining a predicted pixel value from the prediction data according to a preset step, and calculating a first average value of the prediction data according to the predicted pixel value, wherein the preset step is a positive integer except 1;

obtaining a residual of the current image block according to the first average value of the prediction data and a pixel value of a pixel of the current image block; and

coding the residual of the current image block.

2. The method according to claim 1, wherein the obtaining a residual of the current image block according to the first average value of the prediction data and a pixel value of a pixel of the current image block comprises:

performing a difference operation between the pixel value of the pixel of the current image block and the first average value of the prediction data of the current image block to obtain the residual of the current image block;

or

obtaining data of the current image block of the depth map, obtaining a predicted pixel value from the data of the current image block according to the preset step, calculating a second average value of the data of the current image block according to the predicted pixel value of the data of the current image block, and performing a difference operation between the second average value of the data of the current image block and the first average value of reference data of the current image block to obtain the residual of the current image block.

3. The method according to claim 1, wherein the obtaining a predicted pixel value from the prediction data according to a preset step comprises:

using, according to a size of the current image block, an equal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or

using, according to a size of the current image block, an unequal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or

determining the preset step according to a size of the current image block, and obtaining the predicted pixel value according to the preset step.

4. The method according to claim 1, further comprising:

coding a value of the preset step.

5. The method according to claim 1, wherein the preset step is used to identify an interval between position coordinates of the prediction data.

6. The method according to claim 1, wherein the coding the residual of the current image block comprises:

mapping the residual to a mapping value of the residual, wherein the number of bits that represent the mapping value of the residual is less than the number of bits that represent the residual; and

coding the mapping value of the residual.

7. The method according to claim 1, wherein before the obtaining a predicted pixel value from the prediction data according to a preset step, the method further comprises:

determining, according to an intra-frame prediction mode of the current image block, whether the intra-frame prediction mode belongs to a preset intra-frame prediction mode set; and

if yes, determining to obtain the predicted pixel value from the prediction data according to the preset step.

8. The method according to claim 7, wherein the intra-frame prediction mode set comprises at least one of the following intra-frame prediction modes:

a direct current DC mode;

a Planar mode;

an explicit Wedgelet mode; and

an intra-predicted Wedgelet partitioning mode.

9. A method for decoding a depth map, comprising:

obtaining prediction data of a current image block of the depth map, obtaining a predicted pixel value from the prediction data according to a preset step, and calculating a first average value of the prediction data according to the predicted pixel value, wherein the preset step is a positive integer except 1;

obtaining a residual of the current image block; and

obtaining a pixel value of a pixel of the current image block according to the first average value of the prediction data and the residual of the current image block.

10. The method according to claim 9, wherein the obtaining a pixel value of a pixel of the current image block according to the first average value of the prediction data and the residual of the current image block comprises:

adding the first average value of the prediction data of the current image block and the residual of the current image block to obtain the pixel value of the pixel of the current image block;

or

adding the first average value of the prediction data of the current image block and the residual to obtain an average pixel value of the current image block, and using the average pixel value of the current image block as the pixel value of the pixel of the current image block.

11. The method according to claim 9, wherein the obtaining a predicted pixel value from the prediction data according to a preset step comprises:

using, according to a size of the current image block, an equal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or

using, according to a size of the current image block, an unequal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or

determining the preset step according to a size of the current image block, and obtaining the predicted pixel value according to the preset step.

12. The method according to claim 9, further comprising:

parsing a bitstream to obtain a value that identifies the step.

13. The method according to claim 9, wherein the preset step is used to identify an interval between position coordinates of the prediction data.

14. The method according to claim 9, wherein the obtaining a residual of the current image block comprises:

performing decoding processing on a coding result of the current image block to obtain a mapping value of the residual of the current image block; and

mapping the mapping value of the residual to the residual, and using the residual as the residual of the current image block, wherein the number of bits that represent the mapping value of the residual is less than the number of bits that represent the residual.

15. The method according to claim 9, wherein before the obtaining a predicted pixel value from the prediction data according to a preset step, the method further comprises:

determining, according to an intra-frame prediction mode of the current image block, whether the intra-frame prediction mode belongs to a preset intra-frame prediction mode set; and

if yes, determining to obtain the predicted pixel value from the prediction data according to the preset step.

16. The method according to claim 15, wherein the intra-frame prediction mode set comprises at least one of the following intra-frame prediction modes:

a direct current DC mode;

a planar Planar mode;

an explicit Wedgelet mode; and

an intra-predicted Wedgelet partitioning mode.

17. An apparatus for coding a depth map, comprising:

a first processing module, configured to obtain prediction data of a current image block of the depth map, obtain a predicted pixel value from the prediction data according to a preset step, and calculate a first average value of the prediction data according to the predicted pixel value, wherein the preset step is a positive integer except 1;

a second processing module, configured to obtain a residual of the current image block according to the first average value of the prediction data and a pixel value of a pixel of the current image block; and

a coding module, configured to code the residual of the current image block.

18. The apparatus according to claim 17, wherein the second processing module is specifically configured to perform a difference operation between the pixel value of the pixel of the current image block and the first average value of the prediction data of the current image block to obtain the residual of the current image block;

or obtain data of the current image block of the depth map, obtain the predicted pixel value from the data of the current image block according to the preset step, calculate a second average value of the data of the current image block according to the predicted pixel value of the data of the current image block, and perform a difference operation between the second average value of the data of the current image block and the first average value of the prediction data of the current image block to obtain the residual of the current image block.

19. The apparatus according to claim 17, wherein the first processing module is specifically configured to use, according to a size of the current image block, an equal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or use, according to a size of the current image block, an unequal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or determine the preset step according to a size of the current image block, and obtain the predicted pixel value according to the preset step.

20. The apparatus according to claim 17, wherein the coding module is further configured to code a value of the preset step.

21. The apparatus according to claim 17, wherein the preset step is used to identify an interval between position coordinates of the prediction data.

22. The apparatus according to claim 17, wherein the coding module is specifically configured to map the residual to a mapping value of the residual, wherein the number of bits that represent the mapping value of the residual is less than the number of bits that represent the residual, and code the mapping value of the residual.

23. The apparatus according to claim 17, wherein the first processing module is further configured to determine, according to an intra-frame prediction mode of the current image block, whether the intra-frame prediction mode belongs to a preset intra-frame prediction mode set;

and if yes, determine to obtain the predicted pixel value from the prediction data according to the preset step.

24. The apparatus according to claim 23, wherein the intra-frame prediction mode set comprises at least one of the following intra-frame prediction modes:

a direct current DC mode;

a planar Planar mode;

an explicit Wedgelet mode; and

an intra-predicted Wedgelet partitioning mode.

25. An apparatus for decoding a depth map, comprising:

a processing module, configured to obtain prediction data of a current image block of the depth map, obtain a predicted pixel value from the prediction data according to a preset step, and calculate a first average value of the prediction data according to the predicted pixel value, wherein the preset step is a positive integer except 1;

a decoding module, configured to obtain a residual of the current image block, and obtain a pixel value of a pixel of the current image block according to the first average value of the prediction data and the residual of the current image block.

26. The apparatus according to claim 25, wherein the decoding module is specifically configured to add the first average value of the prediction data of the current image block and the residual of the current image block to obtain the pixel value of the pixel of the current image block;

or add the first average value of the prediction data of the current image block and the residual to obtain an average pixel value of the current image block, and use the average pixel value of the current image block as the pixel value of the pixel of the current image block.

27. The apparatus according to claim 25, wherein the processing module is specifically configured to use, according to a size of the current image block, an equal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or use, according to a size of the current image block, an unequal step in a horizontal direction and a vertical direction to obtain the predicted pixel value;

or determine the preset step according to a size of the current image block, and obtain the predicted pixel value according to the preset step.

28. The apparatus according to claim 25, wherein the decoding module is further configured to parse a bitstream to obtain a value that identifies the step.

29. The apparatus according to claim 25, wherein the preset step is used to identify an interval between position coordinates of the prediction data.

30. The apparatus according to claim 25, wherein the decoding module is specifically configured to perform decoding processing on a coding result of the current image block to obtain a mapping value of the residual of the current image block;

and map the mapping value of the residual to the residual, and use the residual as the residual of the current image block, wherein the number of bits that represent the mapping value of the residual is less than the number of bits that represent the residual.

31. The apparatus according to claim 25, wherein the processing module is further configured to determine, according to an intra-frame prediction mode of the current image block, whether the intra-frame prediction mode belongs to a preset intra-frame prediction mode set;

and if yes, determine to obtain the predicted pixel value from the prediction data according to the preset step.

32. The apparatus according to claim 31, wherein the intra-frame prediction mode set comprises at least one of the following intra-frame prediction modes:

a direct current DC mode;

a planar Planar mode;

an explicit Wedgelet mode; and

an intra-predicted Wedgelet partitioning mode.

33. A method for coding a depth map, comprising:

obtaining prediction data of a current image block of the depth map, performing an arithmetic operation on every N pixels among pixels in the prediction data to obtain an arithmetic value of corresponding pixel values, and calculating a first average value of the prediction data according to the arithmetic value of the corresponding pixel values;

obtaining a residual of the current image block according to the first average value of the prediction data and a pixel value of a pixel of the current image block; and

coding the residual of the current image block.

34. The method according to claim 33, wherein the performing an arithmetic operation on every N pixels among pixels in the prediction data to obtain an arithmetic value of corresponding pixel values comprises:

performing an averaging operation on the every N pixels among the pixels in the prediction data to obtain an average pixel value, and using the average pixel value as the arithmetic value of the corresponding pixel values.

35. The method according to claim 33, wherein the obtaining a residual according to the first average value of the prediction data and a pixel value of a pixel of the current image block comprises:

performing a difference operation between the pixel value of the pixel of the image block and the first average value of the prediction data of the current image block to obtain the residual of the current image block;

or

obtaining data of the current image block of the depth map, obtaining a predicted pixel value from the data of the current image block according to a preset step, calculating a second average value of the data of the image block according to the pixel value, and performing a difference operation between the second average value of the image block and the first average value of a reference image block of the current image block to obtain the residual of the current image block.

36. A method for decoding a depth map, comprising:

obtaining prediction data of a current image block of the depth map, performing an arithmetic operation on every N pixels among pixels in the prediction data to obtain an arithmetic value of corresponding pixel values, and calculating a first average value of the prediction data according to the arithmetic value of the corresponding pixel values;

obtaining a residual of the current image block; and

obtaining a pixel value of a pixel of the current image block according to the first average value of the prediction data and the residual of the current image block.

37. The method according to claim 36, wherein the performing an arithmetic operation on every N pixels among pixels in the prediction data to obtain an arithmetic value of corresponding pixel values comprises:

performing an averaging operation on the every N pixels among the pixels in the current image block and the prediction data to obtain an average pixel value, and using the average pixel value as the arithmetic value of the corresponding pixel values.

38. The method according to claim 36, wherein the obtaining a pixel value of a pixel of the current image block according to the first average value of the prediction data and the residual of the current image block comprises:

adding the first average value of the prediction data of the current image block and the residual of the current image block to obtain the pixel value of the pixel of the current image block;

or

adding the first average value of the prediction data of the current image block and the residual to obtain an average pixel value of the current image block, and using the average pixel value of the current image block as the pixel value of the pixel of the current image block.

39. An apparatus for coding a depth map, comprising:

a first processing module, configured to obtain prediction data of a current image block of the depth map, perform an arithmetic operation on every N pixels among pixels in the prediction data to obtain an arithmetic value of corresponding pixel values, and calculate a first average value of the prediction data according to the arithmetic value of the corresponding pixel values;

a second processing module, configured to obtain a residual of the current image block according to the first average value of the prediction data and a pixel value of a pixel of the current image block; and

a coding module, configured to code the residual of the current image block.

40. The apparatus according to claim 39, wherein the first processing module is specifically configured to perform an averaging operation on the every N pixels among the pixels in the prediction data to obtain an average pixel value, and use the average pixel value as the arithmetic value of the corresponding pixel values.

41. The apparatus according to claim 39, wherein the second processing module is specifically configured to perform a difference operation between the pixel value of the pixel of the image block and the first average value of the prediction data of the current image block to obtain the residual of the current image block;

or obtain data of the current image block of the depth map, obtain a predicted pixel value from the data of the current image block according to a preset step, calculate a second average value of the data of the image block according to the pixel value, and perform a difference operation between the second average value of the image block and the first average value of a reference block of the current image block to obtain the residual of the current image block.

42. An apparatus for decoding a depth map, comprising:

a processing module, configured to obtain prediction data of a current image block of the depth map, perform an arithmetic operation on every N pixels among pixels in the prediction data to obtain an arithmetic value of corresponding pixel values, and calculate a first average value of the prediction data according to the arithmetic value of the corresponding pixel values; and

a decoding module, configured to obtain a residual of the current image block, and obtain a pixel value of a pixel of the current image block according to the first average value of the prediction data and the residual of the current image block.

43. The decoding apparatus according to claim 42, wherein the processing module is specifically configured to perform an averaging operation on the every N pixels among the pixels in the current image block and the prediction data to obtain an average pixel value, and use the average pixel value as the arithmetic value of the corresponding pixel values.

44. The apparatus according to claim 42, wherein the decoding module is specifically configured to add the first average value of the prediction data of the current image block and the residual of the current image block to obtain the pixel value of the pixel of the current image block;

or add the first average value of the prediction data of the current image block and the residual to obtain an average pixel value of the current image block, and use the average pixel value of the current image block as the pixel value of the pixel of the current image block.