Palette mode for subsampling format

Patent metadata

Field	Value
Publication number	US-10097839-B2
Application number	US-201514973648-A
Country	US
Kind code	B2
Filing date	Dec 17, 2015
Priority date	Dec 19, 2014
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

Techniques are described to extend palette-mode coding techniques to cases where chroma components are at a different resolution than luma components. The entries of the palette table includes three color values and the three color values or a single one of the three color values are selected based on whether a pixel includes both a luma component and chroma components or only a luma component.

First claim

What is claimed is:

1. A method of decoding video data, the method comprising:
deriving a single palette table, for a current block of the video data, that includes entries having three color values;
determining whether a pixel in a current block of the video data includes a luma component and chroma components;
determining that only a single color value of the three color values is to be retrieved from the single palette table based on a determination that the pixel in the current block includes only the luma component and none of the chroma components; and
palette-mode decoding the pixel in the current block of the video data by retrieving the single color value from the single palette table and assigning the single color value to the luma component of the pixel.

2. The method of claim 1 , further comprising:
determining a phase alignment between luma components of the current block and chroma components of the current block,
wherein determining whether the pixel in the current block includes the luma component and the chroma components comprises determining whether the pixel in the current block includes the luma component and the chroma components based on the determined phase alignment.

3. The method of claim 1 , further comprising determining a second number of color values to retrieve from a second single palette table based on a determination of whether a pixel in a second block of the video data includes a luma component and chroma components, wherein determining the second number of color values comprises determining that three color values are to be retrieved from the second single palette table based on a determination that the pixel in the second block includes the luma component and the chroma components, and wherein palette-mode decoding the pixel in the second block comprises retrieving the three color values from the second single palette table and assigning each of the three color values to respective luma and chroma components of the pixel in the second block.

4. The method of claim 1 , wherein the single color value comprises a first identified color value of the three color values.

5. The method of claim 1 , wherein the pixel comprises a first pixel, the method further comprising:
determining that a second pixel in the current block is not to be decoded based on the single palette table;
determining whether the second pixel in the current block includes a luma component and chroma components;
determining a number of color values to parse from a bitstream based on the determination of whether the second pixel in the current block includes the luma component and the chroma components; and
decoding the second pixel in the current block based on the determined number of color values to parse from the bitstream.

6. The method of claim 5 , wherein determining the number of color values to parse from the bitstream comprises determining that three color values are to be parsed from the bitstream based on a determination that the second pixel in the current block includes the luma component and the chroma components.

7. The method of claim 5 , wherein determining the number of color values to parse from the bitstream comprises determining that only a single color value is to be parsed from the bitstream based on a determination that the second pixel in the current block includes only the luma component and none of the chroma components.

8. The method of claim 1 , further comprising:
receiving a single index identifying one entry in the single palette table,
wherein determining that only the single color value of the three color values is to be retrieved from the single palette table comprises determining a number of color values to retrieve from the identified entry in the single palette table based on the determination of whether the pixel in the current block includes the luma component and the chroma components.

9. A device for decoding video data, the device comprising:
a memory unit configured to store a palette table, for a current block of the video data, that includes entries having three color values; and
a video decoder configured to:
derive the palette table for the current block of the video data, and no other palette table for the current block, for storage in the memory unit;
determine whether a pixel in the current block of the video data includes a luma component and chroma components;
determine that only a single color value of the three color values is to be retrieved from the single palette table based on a determination that the pixel in the current block includes only the luma component and none of the chroma components; and
palette-mode decode the pixel in the current block of the video data by retrieving the single color value from the single palette table and assigning the single color value to the luma component of the pixel.

10. The device of claim 9 , wherein the video decoder is configured to:
determine a phase alignment between luma components of the current block and chroma components of the current block,
wherein to determine whether the pixel in the current block includes the luma component and the chroma components, the video decoder is configured to determine whether the pixel in the current block includes the luma component and the chroma components based on the determined phase alignment.

11. The device of claim 9 , wherein the video decoder is configured to:
determine a number of color values by determining that three color values are to be retrieved from the palette table based on a determination that the pixel in the current block includes the luma component and the chroma components; and
palette-mode decode the pixel in the current block by retrieving the three color values from the palette table and assigning each of the three color values to respective luma and chroma components of the pixel.

12. The device of claim 9 , wherein the single color value comprises a first identified color value of the three color values.

13. The device of claim 9 , wherein the pixel comprises a first pixel, and wherein the video decoder is configured to:
determine that a second pixel in the current block is not to be decoded based on the palette table;
determine whether the second pixel in the current block includes a luma component and chroma components;
determine a number of color values to parse from a bitstream based on the determination of whether the second pixel in the current block includes the luma component and the chroma components; and
decode the second pixel in the current block based on the determined number of color values to parse from the bitstream.

14. The device of claim 13 , wherein to determine the number of color values to parse from the bitstream, the video decoder is configured to determine that three color values are to be parsed from the bitstream based on a determination that the second pixel in the current block includes the luma component and the chroma components.

15. The device of claim 13 , wherein to determine the number of color values to parse from the bitstream, the video decoder is configured to determine that only a single color value is to be parsed from the bitstream based on a determination that the second pixel in the current block includes only the luma component and none of the chroma components.

16. The device of claim 9 , wherein the video decoder is configured to:
receive a single index identifying one entry in the palette table,
wherein to determine that only the single color value of the three color values is to be retrieved from the single palette table comprises determining the num

Assignees

• Qualcomm Inc

Inventors

• Joshi Rajan Laxman
• Seregin Vadim
• Pu Wei
• Sole Rojals Joel
• Karczewicz Marta
• Zou Feng

Classifications

• H04N19/182

  the unit being a pixel · CPC title

• H04N19/124

  Quantisation · CPC title

• H04N19/186 Primary

  the unit being a colour or a chrominance component · CPC title

• H04N19/45

  performing compensation of the inverse transform mismatch, e.g. Inverse Discrete Cosine Transform [IDCT] mismatch · CPC title

• H04N19/90

  using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals · CPC title