Palette mode for subsampling format

Patent metadata

Field	Value
Publication number	US-2016182913-A1
Application number	US-201514973648-A
Country	US
Kind code	A1
Filing date	Dec 17, 2015
Priority date	Dec 19, 2014
Publication date	Jun 23, 2016
Grant date	—

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 a number of color values to retrieve from the single palette table based on the determination of whether the pixel in the current block includes the luma component and the chroma components; and palette-mode decoding the pixel in the current block of the video data based on the determination of the number of color values to retrieve.

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 , wherein determining the number of color values comprises determining that three color values are to be retrieved from the single palette table based on the determination that the pixel in the current block includes the luma component and the chroma components, and wherein palette-mode decoding the pixel in the current block comprises retrieving the three color values from the single palette table and assigning each of the three color values to respective luma and chroma components of the pixel.

4 . The method of claim 1 , wherein determining the number of color values comprises determining that only a single color value of the three color values is to be retrieved from the single palette table based on the determination that the pixel in the current block includes only the luma component and none of the chroma components, and wherein palette-mode decoding the pixel in the current block comprises retrieving the single color value from the single palette table and assigning the single color value to the luma component of the pixel.

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

6 . 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.

7 . The method of claim 6 , 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 the determination that the second pixel in the current block includes the luma component and the chroma components.

8 . The method of claim 6 , 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 the determination that the second pixel in the current block includes only the luma component and none of the chroma components.

9 . The method of claim 1 , further comprising:
receiving a single index identifying one entry in the single palette table, wherein determining the number of color values to retrieve comprises determining the 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.

10 . 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 a number of color values to retrieve from the palette table based on the determination of whether the pixel in the current block includes the luma component and the chroma components; and
palette-mode decode the pixel in the current block of the video data based on the determination of the number of color values to retrieve.

11 . The device of claim 10 , 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.

12 . The device of claim 10 , wherein to determine the number of color values, the video decoder is configured to determine that three color values are to be retrieved from the palette table based on the determination that the pixel in the current block includes the luma component and the chroma components, and wherein to palette-mode decode the pixel in the current block, the video decoder is configured to retrieve the three color values from the palette table and assign each of the three color values to respective luma and chroma components of the pixel.

13 . The device of claim 10 , wherein to determine the number of color values, the video decoder is configured to determine that only a single color value of the three color values is to be retrieved from the palette table based on the determination that the pixel in the current block includes only the luma component and none of the chroma components, and wherein to palette-mode decode the pixel in the current block, the video decoder is configured to retrieve the single color value from the palette table and assign the single color value to the luma component of the pixel.

14 . The device of claim 13 , wherein the single color value comprises a first identified color value of the three color values.

15 . The device of claim 10 , 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.

16 . The device of claim 15 , 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 the determination that the second pixel in the current block includes the luma component and the chroma components.

Assignees

• Qualcomm Inc

Inventors

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

Classifications

• H04N19/176 Primary

  the region being a block, e.g. a macroblock · CPC title

• H04N19/182

  the unit being a pixel · CPC title

• H04N19/61

  in combination with predictive coding · CPC title

• H04N19/59

  involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution · CPC title

• H04N19/90

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