Combined scalability processing for multi-layer video coding
A video coding system may perform inter-layer processing by simultaneously performing inverse tone mapping and color gamut conversion scalability processes on a base layer of a video signal. The video coding system may then perform upsampling on the processed base layer. The processed base layer may be used to code an enhancement layer. Bit depth may be considered for color gamut conversion modules. Luma and/or chroma bit depths may be aligned with respective larger or smaller bit depth values of luma and/or chroma.
1. A method of decoding a video signal, the method comprising:
receiving the video signal;
reconstructing a picture from the video signal;
performing bit depth alignment on a luma component of the picture and a chroma component of the picture such that the luma and chroma components have a same aligned bit depth; and
performing color mapping on the bit depth-aligned luma and chroma components of the picture.
2. The method of claim 1 , wherein performing bit depth alignment further comprises:
aligning a first bit depth of the luma component to a second bit depth of the chroma component.
3. The method of claim 1 , wherein performing bit depth alignment further comprises:
aligning a first bit depth of the chroma component to a second bit depth of the luma component.
4. The method of claim 1 , wherein performing bit depth alignment further comprises:
determining a maximum color component bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
aligning the first bit depth of the luma component and the second bit depth of the chroma component to the maximum color component bit depth.
5. The method of claim 4 , wherein the maximum color component bit depth is the greater of the first bit depth of the luma component and the second bit depth of the chroma component.
6. The method of claim 1 , wherein performing bit depth alignment further comprises:
determining a minimum color component bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
aligning the first bit depth of the luma component and the second bit depth of the chroma component to the minimum color component bit depth.
7. The method of claim 6 , wherein the minimum color component bit depth is the less of the first bit depth of the luma component and the second bit depth of the chroma component.
8. The method of claim 1 , wherein the video signal comprises a base layer (BL) and an enhancement layer (EL), the picture is a BL picture from the BL, and performing color mapping on the bit depth-aligned luma and chroma components of the BL picture further comprises:
applying a cross color component model to the bit depth-aligned luma and chroma components to generate an inter-layer reference picture, wherein the inter-layer reference picture is used to predict at least one EL picture from the EL of the video signal.
9. The method of claim 1 , wherein performing bit depth alignment further comprises:
determining a luma delta bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
shifting a luma sample value for the luma component by the determined luma delta bit depth.
10. The method of claim 1 , wherein performing bit depth alignment further comprises:
determining a bit depth difference between a first bit depth of the luma component and a second bit depth of the chroma component; and
scaling a sample value for color component with a lower bit depth to match the bit depth of the color component with a higher bit depth.
11. A video decoding device comprising:
a processor configured to:
receive video signal;
reconstruct a picture from the video signal;
perform bit depth alignment on a luma component of the picture and a chroma component of the picture such that the luma and chroma components have a same aligned bit depth; and
perform color mapping on the bit depth-aligned luma and chroma components of the picture.
12. The video decoding device of claim 11 , wherein the processor is configured to perform bit depth alignment by:
aligning a first bit depth of the luma component to a second bit depth of the chroma component.
13. The video decoding device of claim 11 , wherein the processor is configured to perform bit depth alignment by:
aligning a first bit depth of the chroma component to a second bit depth of the luma component.
14. The video decoding device of claim 11 , wherein the processor is configured to perform bit depth alignment by:
determining a maximum color component bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
aligning the first bit depth of the luma component and the second bit depth of the chroma component to the maximum color component bit depth.
15. The video decoding device of claim 14 , wherein the maximum color component bit depth is the greater of the first bit depth of the luma component and the second bit depth of the chroma component.
16. The video decoding device of claim 11 , wherein the processor is configured to perform bit depth alignment by:
determining a minimum color component bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
aligning the first bit depth of the luma component and the second bit depth of the chroma component to the minimum color component bit depth.
17. The video decoding device of claim 16 , wherein the minimum color component bit depth is the less of the first bit depth of the luma component and the second bit depth of the chroma component.
18. The video decoding device of claim 11 , wherein video signal comprises a base layer (BL) and an enhancement layer (EL), the picture is BL picture from the BL, and the processor is configured to perform color mapping on the bit depth-aligned luma and chroma components of the BL picture by:
applying a cross color component model to the bit depth-aligned luma and chroma components to generate an inter-layer reference picture, wherein the inter-layer reference picture is used to predict at least one EL picture from the EL of the video signal.
19. The video decoding device of claim 11 , wherein the processor is configured to perform bit depth alignment by:
determining a luma delta bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
shifting a luma sample value for the luma component by the determined luma delta bit depth.
20. The video decoding device of claim 11 , wherein the processor is configured to perform bit depth alignment by:
determining a bit depth difference between a first bit depth of the luma component and a second bit depth of the chroma component; and
scaling a sample value for a color component with a lower bit depth to match the bit depth of the color component with a higher bit depth.
21. A method of encoding a video signal, the method comprising:
receiving a picture from the video signal;
performing bit depth alignment on a luma component of the picture and a chroma component of the picture such that the luma and chroma components have a same aligned bit depth;
performing color mapping on the bit depth-aligned luma and chroma components of the picture; and
encoding the picture from the video signal.
22. The method of claim 21 , further comprising:
aligning a first bit depth of the luma component to a second bit depth of the chroma component.
23. The method of claim 21 , further comprising:
aligning a first bit depth of the chroma component to a second bit depth of the luma component.
24. A video encoding device comprising:
a processor configured to:
receive a picture from a video signal;
perform bit depth alignment on a luma component of the picture and a chroma component of the picture such that the luma and chroma components have a same aligned bit depth;
perform color mapping on the bit depth-aligned luma and chroma components of the picture; and
encode the picture from the video signal.
25. The video encoding device of claim 24 , wherein the processor is further configured to:
determine a maximum color component bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
align the first bit depth of the luma component and the second bit depth of the chroma component to the maximum color component bit depth.
26. The video encoding device of claim 24 , wherein the processor is further configured to:
determine a minimum color component bit depth based on a first bit depth of the luma component and a second bit depth of the chroma component; and
align the first bit depth of the luma component and the second bit depth of the chroma component to the minimum color component bit depth.