| 摘要 |
A current image pixel block is processed (coded) using palette coding mode, using a current palette to build a predictor indexes block to predict the current block, the current palette entries associating indexes with pixel values. An input palette is generated from the block pixels and post-processed to produce the current palette by setting (substituting) the input palette entry value to a value according to a criterion on the entry. Also, a palette used to encode a pixel block is determined by incrementing an element counter or adding a new element according to closeness of a pixel to existing elements. If incrementing, the associated element is modified according to all associated pixels, e.g. calculating mean, median or mode. Further, a coding mode, including a palette mode, is selected from a plurality based on rate-distortion criterion. The palette is iteratively built from current block pixel values based on a threshold of distance between pixels and existing palette elements. The selection iteratively determines a rate-distortion criterion for each palette coding mode, each having different threshold values to build their palettes and which are successively tested to establish the best criterion. The methods relate to HEVC RExt defining Palette Coding Mode for screen contents coding. |
