Lossy image compression using palettization of locally mixed colors
AssigneeGoogle Inc.
InventorsJyrki Alakuijala, Alexander Rhatushnyak
Life of this patent
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Abstract
An apparatus includes a processor that is configured to select a palette entry in the palette for coding a value of a pixel of the image block; obtain respective palette indexes of neighboring pixels of the pixel; select, using the respective palette indexes, an entropy code for coding an index of the palette entry; and code the palette entry using the entropy code. A method includes obtaining respective palette indexes of neighboring pixels of a pixel of the image block; selecting an entropy code using the respective palette indexes; decoding, from a encoded bitstream, an index of a palette entry; and setting a value of the pixel using the palette entry.
Claims20
An apparatus for coding an image block using a palette, comprising:
- a processor configured to:
- select a palette entry in the palette for coding a value of a pixel of the image block;
- obtain respective palette indexes of neighboring pixels of the pixel, wherein the neighboring pixels comprise a top neighbor and a left neighbor of the pixel of the image block;
- select, using the respective palette indexes, an entropy code for coding an index of the palette entry;
- and
- code the index of the palette entry using the entropy code.
A method for decoding an image block using a palette, comprising:
- obtaining respective palette indexes of neighboring pixels of a pixel of the image block;
- selecting an entropy code using the respective palette indexes;
- decoding, from an encoded bitstream and based on the entropy code, an index of a palette entry;
- and
- setting a value of the pixel using the palette entry.
An apparatus for decoding an image block, comprising:
- a processor configured to:
- select a fixed palette including fixed palette entries;
- select a mixed palette including mixed palette entries,
- each mixed palette entry respectively indicates, with respect to a to-be-decoded pixel, a recipe for combining color values of pixels of a pixel neighborhood of the to-be-decoded pixel, wherein the pixel neighborhood indicates, for the to-be-decoded pixel, locations of pixels proximal to the to-be-decoded pixel whose color values are to be combined to decode the to-be-decoded pixel;
- and
- decode first pixels of the image block using the mixed palette.
Dependencies are inferred from the claim text.