METHOD AND APPARATUS FOR ENCODING OR DECODING BLOCKS OF PIXEL

摘要

The invention concerns a method and a device for processing a current pixel block of an image using a palette prediction mode according to HEVC RExt. The mode uses a current palette to build a predictor block of indexes to predict the current pixel block. The current palette comprises entries associating entry indexes with pixel values. The method comprises predicting the current palette from entries of two or more palettes that are palettes previously used to process blocks of pixels. A palette predictor may be used that is built from the two or more palettes, preferably from the last used palette for a coding unit in the current coding entity and from the previously used palette for which a flag bitmap indicates whether or not its elements have been copied into the last used palette. Accordingly, the coding of the palette mode is improved.

主权项

1. A method for processing a current block of pixels of an image using a palette coding mode, the palette coding mode using a current palette that comprises a set of entries associating respective entry indexes with corresponding pixel values, the method comprising:
a step of predicting the current palette using a palette predictor built from entries of two or more palettes, the two or more palettes being palettes previously used to process blocks of pixels, wherein the prediction of the current palette comprises selecting an entry from a given palette of the two or more palettes as an entry of the palette predictor and selecting all the entries from another of the two or more palettes as entries of the palette predictor, said another palette being used to process the block of pixels immediately preceding the current block, wherein said selection of an entry from the given palette being is based on a 10 bitmap of flags, each flag defining whether or not a corresponding entry in the given palette is selected as an entry in the another palette, and includes selecting an entry of the given palette corresponding to a flag of the bitmap that defines no selection of the entry as the entry of the given palette to be included in the palette predictor for predicting the current palette.