SIGNALING BIT DEPTH VALUES FOR 3D COLOR PREDICTION FOR COLOR GAMUT SCALABILITY

• US 20150304628A1
• Filed: 04/16/2015
• Published: 10/22/2015
• Est. Priority Date: 04/17/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Li, Xiang, Chen, Jianle, Karczewicz, Marta
• Granted Patent: US 10,448,029 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 13/161 Encoding, multiplexing or demultiplexing different image signal components for multi-view video sequence encoding H04N19/597
• 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 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/36 Scalability techniques involving formatting the layers as a function of picture distortion after decoding, e.g. signal-to-noise [SNR] scalability
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/597 specially adapted for multi-view video sequence encoding

Abstract

Techniques are described for performing constrained three-dimensional (3D) color prediction for color gamut scalability in video coding. Color prediction techniques for color gamut scalability may be used by video coders to generate inter-layer reference pictures when a color gamut for a reference layer of video data is different than a color gamut for an enhancement layer of the video data, or when a bit depth of the reference layer is different than a bit depth of the enhancement layer. According to the techniques, a video coder may perform 3D color prediction with constrained bit depths of input and output color components of the 3D lookup table. According to further techniques, in the case of multiple layers, a video coder may perform 3D color prediction with constrained application to reference pictures in only one or more identified reference layers.

Claims

1. A method of decoding video data, the method comprising:

determining input bit depths of a three-dimensional (3D) lookup table for color gamut scalability to be equal to bit depths of color components of a reference layer picture in a reference layer of the video data;

applying the 3D lookup table to the color components of the reference layer picture to convert the color components from a first color gamut for the reference layer of the video data to a second color gamut for an enhancement layer of the video data;

generating an inter-layer reference picture for an enhancement layer picture in the enhancement layer of the video data based on the converted color components; and

decoding video blocks of the enhancement layer picture based on the inter-layer reference picture generated using the 3D lookup table.

2. The method of claim 1, wherein determining the input bit depths of the 3D lookup table comprises:

receiving a first syntax element indicating a first bit depth for an input luma component of the 3D lookup table, the first bit depth being constrained to be equal to a bit depth of a luma component of the reference layer picture; and

receiving a second syntax element indicating a second bit depth for input chroma components of the 3D lookup table, the second bit depth being constrained to be equal to a bit depth of chroma components of the reference layer picture.

3. The method of claim 1, wherein determining the input bit depths of the 3D lookup table comprises:

deriving a first bit depth for an input luma component of the 3D lookup table to be equal to a bit depth of a luma component of the reference layer picture; and

deriving a second bit depth for input chroma components of the 3D lookup table to be equal to a bit depth of chroma components of the reference layer picture.

4. The method of claim 1, further comprising determining output bit depths of the 3D lookup table to be within a range that is greater than or equal to the bit depths of the color components of the reference layer picture and less than or equal to bit depths of color components of the enhancement layer picture.

5. The method of claim 4, wherein determining the output bit depths of the 3D lookup table comprises:

receiving a first syntax element indicating a first bit depth for an output luma component of the 3D lookup table, the first bit depth being constrained to be greater than or equal to a bit depth of a luma component of the reference layer picture and less than or equal to a bit depth of a luma component of the enhancement layer picture; and

receiving a second syntax element indicating a second bit depth for output chroma components of the 3D lookup table, the second bit depth being constrained to be greater than or equal to a bit depth of chroma components of the reference layer picture and less than or equal to a bit depth of chroma components of the enhancement layer picture.

6. The method of claim 4, wherein determining the output bit depths of the 3D lookup table comprises:

deriving a first bit depth for an output luma component of the 3D lookup table to be greater than or equal to a bit depth of a luma component of the reference layer picture and less than or equal to a bit depth of a luma component of the enhancement layer picture; and

deriving a second syntax element indicating a second bit depth for output chroma components of the 3D lookup table to be greater than or equal to a bit depth of chroma components of the reference layer picture and less than or equal to a bit depth of chroma components of the enhancement layer picture.

7. The method of claim 1, further comprising determining output bit depths of the 3D lookup table to be equal to bit depths of color components of the enhancement layer picture.

8. A method of encoding video data, the method comprising:

determining input bit depths of a three-dimensional (3D) lookup table for color gamut scalability to be equal to bit depths of color components of a reference layer picture in a reference layer of the video data;

applying the 3D lookup table to the color components of the reference layer picture to convert the color components from a first color gamut for the reference layer of the video data to a second color gamut for an enhancement layer of the video data;

generating an inter-layer reference picture for an enhancement layer picture in the enhancement layer of the video data based on the convened color components; and

encoding video blocks in the enhancement layer picture based on the inter-layer reference picture generated using the 3D lookup table.

9. The method of claim 8, further comprising:

signaling a first syntax element indicating a first bit depth for an input luma component of the 3D lookup table, the first bit depth being constrained to be equal to a bit depth of a luma component of the reference layer picture; and

signaling a second syntax element indicating a second bit depth for input chroma components of the 3D lookup table, the second bit depth being constrained to be equal to a bit depth of chroma components of the reference layer picture.

10. The method of claim 8, further comprising determining output bit depths of the 3D lookup table to be within a range that is greater than or equal to the bit depths of the color components of the reference layer picture and less than or equal to bit depths of color components of the enhancement layer picture.

11. The method of claim 10, further comprising:

signaling a first syntax element indicating a first bit depth for an output luma component of the 3D lookup table, the first bit depth being constrained to be greater than or equal to a bit depth of a luma component of the reference layer picture and less than or equal to a bit depth of a luma component of the enhancement layer picture; and

signaling a second syntax element indicating a second bit depth for output chroma components of the 3D lookup table, the second bit depth being constrained to be greater than or equal to a bit depth of chroma components of the reference layer picture and less than or equal to a bit depth of chroma components of the enhancement layer picture.

12. The method of claim 8, further comprising determining output bit depths of the 3D lookup table to be equal to bit depths of color components of the enhancement layer picture.

13. A video decoding device comprising:

a memory configured to store video data; and

one or more processors in communication with the memory and configured to;

determine input bit depths of a three-dimensional (3D) lookup table for color gamut scalability to be equal to bit depths of color components of a reference layer picture in a reference layer of the video data;

apply the 3D lookup table to the color components of the reference layer picture to convert the color components from a first color gamut for the reference layer of the video data to a second color gamut for an enhancement layer of the video data;

generate an inter-layer reference picture for an enhancement layer picture in the enhancement layer of the video data based on the converted color components; and

decode video blocks of the enhancement layer picture based on the inter-layer reference picture generated using the 3D lookup table.

14. The device of claim 13, wherein, to determine the input bit depths of the 3D lookup table, the one or more processors are configured to:

receive a first syntax element indicating a first bit depth for an input luma component of the 3D lookup table, the first bit depth being constrained to be equal to a bit depth of a luma component of the reference layer picture; and

receive a second syntax element indicating a second bit depth for input chroma components of the 3D lookup table, the second bit depth being constrained to be equal to a bit depth of chroma components of the reference layer picture.

15. The device of claim 13, wherein, to determine the input bit depths of the 3D lookup table, the one or more processors are configured to:

derive a first bit depth for an input luma component of the 3D lookup table to be equal to a bit depth of a luma component of the reference layer picture; and

derive a second bit depth for input chroma components of the 3D lookup table to be equal to a bit depth of chroma components of the reference layer picture.

16. The device of claim 13, wherein the one or more processors are configured to determine output bit depths of the 3D lookup table to be within a range that is greater than or equal to the bit depths of the color components of the reference layer picture and less than or equal to bit depths of color components of the enhancement layer picture.

17. The device of claim 16, wherein, to determine the output bit depths of the 3D lookup table, the one or more processors are configured to:

receive a first syntax element indicating a first bit depth for an output luma component of the 3D lookup table, the first bit depth being constrained to be greater than or equal to a bit depth of a luma component of the reference layer picture and less than or equal to a bit depth of a luma component of the enhancement layer picture; and

receive a second syntax element indicating a second bit depth for output chroma components of the 3D lookup table, the second bit depth being constrained to be greater than or equal to a bit depth of chroma components of the reference layer picture and less than or equal to a bit depth of chroma components of the enhancement layer picture.

18. The device of claim 16, wherein, to determine the output bit depths of the 3D lookup table, the one or more processors are configured to:

derive a first bit depth for an output luma component of the 3D lookup table to be greater than or equal to a bit depth of a luma component of the reference layer picture and less than or equal to a bit depth of a luma component of the enhancement layer picture; and

derive a second syntax element indicating a second bit depth for output chroma components of the 3D lookup table to be greater than or equal to a bit depth of chroma components of the reference layer picture and less than or equal to a bit depth of chroma components of the enhancement layer picture.

19. The device of claim 13, wherein the one or more processors are configured to determine output bit depths of the 3D lookup table to be equal to bit depths of color components of the enhancement layer picture.

20. A video encoding device comprising:

a memory configured to store video data; and

one or more processors in communication with the memory and configured to;

determine input bit depths of a three-dimensional (3D) lookup table for color gamut scalability to be equal to bit depths of color components of a reference layer picture in a reference layer of the video data;

apply the 3D lookup table to the color components of the reference layer picture to convert the color components from a first color gamut for the reference layer of the video data to a second color gamut for an enhancement layer of the video data;

generate an inter-layer reference picture for an enhancement layer picture in the enhancement layer of the video data based on the converted color components; and

encode video blocks in the enhancement layer picture based on the inter-layer reference picture generated using the 3D lookup table.

21. The device of claim 20, wherein the one or more processors are configured to:

signal a first syntax element indicating a first bit depth for an input luma component of the 3D lookup table, the first bit depth being constrained to be equal to a bit depth of a luma component of the reference layer picture; and

signal a second syntax element indicating a second bit depth for input chroma components of the 3D lookup table, the second bit depth being constrained to be equal to a bit depth of chroma components of the reference layer picture.

22. The device of claim 20, wherein the one or more processors are configured to determine output bit depths of the 3D lookup table to be within a range that is greater than or equal to the bit depths of the color components of the reference layer picture and less than or equal to bit depths of color components of the enhancement layer picture.

23. The device of claim 22, wherein the one or more processors are configured to:

signal a first syntax element indicating a first bit depth for an output luma component of the 3D lookup table, the first bit depth being constrained to be greater than or equal to a bit depth of a luma component of the reference layer picture and less than or equal to a bit depth of a luma component of the enhancement layer picture; and

signal a second syntax element indicating a second bit depth for output chroma components of the 3D lookup table, the second bit depth being constrained to be greater than or equal to a bit depth of chroma components of the reference layer picture and less than or equal to a bit depth of chroma components of the enhancement layer picture.

24. The device of claim 20, wherein the one or more processors are configured to determine output bit depths of the 3D lookup table to be equal to bit depths of color components of the enhancement layer picture.

25. A video decoding device comprising:

means for determining input bit depths of a three-dimensional (3D) lookup table for color gamut scalability to be equal to bit depths of color components of a reference layer picture in a reference layer of the video data;

means for applying the 3D lookup table to the color components of the reference layer picture to convert the color components from a first color gamut for the reference layer of the video data to a second color gamut for an enhancement layer of the video data;

means for generating an inter-layer reference picture for an enhancement layer picture in the enhancement layer of the video data based on the converted color components; and

means for decoding video blocks of the enhancement layer picture based on the inter-layer reference picture generated using the 3D lookup table.

26. The device of claim 25, further comprising means for determining output bit depths of the 3D lookup table to be within a range that is greater than or equal to the bit depths of the color components of the reference layer picture and less than or equal to bit depths of color components of the enhancement layer picture.

27. A computer-readable storage medium storing instructions for decoding video data that, when executed, cause one or more processors to:

determine input bit depths of a three-dimensional (3D) lookup table for color gamut scalability to be equal to bit depths of color components of a reference layer picture in a reference layer of the video data;

apply the 3D lookup table to the color components of the reference layer picture to convert the color components from a first color gamut for the reference layer of the video data to a second color gamut for an enhancement layer of the video data;

generate an inter-layer reference picture for an enhancement layer picture in the enhancement layer of the video data based on the converted color components; and

decode video blocks of the enhancement layer picture based on the inter-layer reference picture generated using the 3D lookup table.

28. The computer-readable storage medium of claim 27, further comprising instructions that cause the one or more processor to determine output bit depths of the 3D lookup table to be within a range that is greater than or equal to the bit depths of the color components of the reference layer picture and less than or equal to bit depths of color components of the enhancement layer picture, inclusively.