Method for encoding and method for decoding a color transform and corresponding devices

1. A non-transitory processor-readable storage medium comprising instructions that cause a processor to perform:

decoding first parameters representative of video signal characteristics of decoded pictures color mapped by at least one color transform, the first parameters comprising at least one syntax element of a plurality of syntax elements, each syntax element of the plurality of syntax elements (i) describing the decoded pictures color mapped by the at least one color transform and (ii) having the same semantics as a corresponding video usability information (VUI) syntax element; and

decoding second parameters representative of the at least one color transform.

2. The storage medium according to claim 1 , wherein the first parameters comprise at least one of the following syntax elements:

a video signal range indicating a black level and range of the color components;

color primaries;

a transfer characteristic; and

matrix coefficients for deriving luma and chroma signals from RGB primaries.

3. The storage medium according to claim 1 , wherein the first parameters further comprise a fifth syntax element for identifying a purpose of a color mapping model.

4. The storage medium according to claim 1 , wherein the first and second parameters are encoded in a Supplemental Enhancement Information message.

5. The storage medium according to claim 4 , wherein the first parameters further comprise a sixth syntax element indicating that the color mapping information Supplemental Enhancement Information message cancels persistence of any previous color mapping information Supplemental Enhancement Information message in output order in the case where the sixth syntax element equals to 1 and indicating that color mapping information follows in the case where the sixth syntax element equals to 0.

6. The storage medium according to claim 4 , wherein the first parameters further comprise a seventh syntax element specifying persistence of the color mapping information Supplemental Enhancement Information message.

7. An apparatus comprising:

a processor operably coupled with a memory and configured to perform:

transmitting first parameters representative of video signal characteristics of decoded pictures color mapped by at least one color transform, the first parameters comprising at least one syntax element of a plurality of syntax elements, each syntax element of the plurality of syntax elements (i) describing the decoded pictures color mapped by the at least one color transform and (ii) having the same semantics as a corresponding video usability information (VUI) syntax element; and

transmitting second parameters representative of the at least one color transform.

8. The apparatus according to claim 7 , wherein the first parameters comprise at least one of the following syntax elements:

a video signal range indicating a black level and range of the color components;

color primaries;

a transfer characteristic; and

matrix coefficients for deriving luma and chroma signals from RGB primaries.

9. The apparatus according to claim 7 , wherein the first parameters further comprise a fifth syntax element for identifying a purpose of a color mapping model.

10. The apparatus according to claim 7 , wherein the first and second parameters are encoded in a Supplemental Enhancement Information message.

11. The apparatus according to claim 10 , wherein the first parameters further comprise a sixth syntax element indicating that the color mapping information Supplemental Enhancement Information message cancels persistence of any previous color mapping information Supplemental Enhancement Information message in output order in the case where the sixth syntax element equals to 1 and indicating that color mapping information follows in the case where the sixth syntax element equals to 0.

12. The apparatus according to claim 10 , wherein the first parameters further comprise a seventh syntax element specifying persistence of the color mapping information Supplemental Enhancement Information message.

13. A method comprising:

transmitting first parameters representative of video signal characteristics of decoded pictures color mapped by at least one color transform, the first parameters comprising at least one syntax element of a plurality of syntax elements, each syntax element of the plurality of syntax elements (i) describing the decoded pictures color mapped by the at least one color transform and (ii) having the same semantics as a corresponding video usability information (VUI) syntax element; and

transmitting second parameters representative of the at least one color transform.

14. The method according to claim 13 , wherein the first parameters representative of video signal characteristics comprise at least one of the following syntax elements:

a video signal range indicating a black level and range of the color components;

color primaries;

a transfer characteristic; and

matrix coefficients for deriving luma and chroma signals from RGB primaries.

15. The method according to claim 13 , wherein the first parameters further comprise a fifth syntax element for identifying a purpose of a color mapping model.

16. The method according to claim 13 , wherein the first and second parameters are encoded in a Supplemental Enhancement Information message.

17. The method according to claim 16 , wherein the first parameters further comprise a sixth syntax element indicating that the color mapping information Supplemental Enhancement Information message cancels persistence of any previous color mapping information Supplemental Enhancement Information message in output order in the case where the sixth syntax element equals to 1 and indicating that color mapping information follows in the case where the sixth syntax element equals to 0.

18. The method according to claim 16 , wherein the first parameters further comprise a seventh syntax element specifying persistence of the color mapping information Supplemental Enhancement Information message.

19. The method according to claim 16 , wherein the plurality of syntax elements comprises:

a first syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the first syntax element has the same semantics as a Video Usability Information video full range flag syntax element;

a second syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the second syntax element has the same semantics as a Video Usability Information color primaries syntax element;

a third syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the third syntax element has the same semantics as a Video Usability Information transfer characteristics syntax element; and

a fourth syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the fourth syntax element has the same semantics as a Video Usability Information matrix coefficients syntax element.

20. The apparatus according to claim 7 , wherein the plurality of syntax elements comprises:

a first syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the first syntax element has the same semantics as a Video Usability Information video full range flag syntax element;

a second syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the second syntax element has the same semantics as a Video Usability Information color primaries syntax element;

a third syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the third syntax element has the same semantics as a Video Usability Information transfer characteristics syntax element; and

a fourth syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the fourth syntax element has the same semantics as a Video Usability Information matrix coefficients syntax element.

21. The non-transitory processor-readable storage medium of claim 1 , wherein the plurality of syntax elements comprises:

a first syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the first syntax element has the same semantics as a Video Usability Information video full range flag syntax element;

a second syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the second syntax element has the same semantics as a Video Usability Information color primaries syntax element;

a third syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the third syntax element has the same semantics as a Video Usability Information transfer characteristics syntax element; and

a fourth syntax element describing the decoded pictures color mapped by the at least one color transform, wherein the fourth syntax element has the same semantics as a Video Usability Information matrix coefficients syntax element.