| 摘要 |
A method and apparatus for improved intra chroma prediction mode coding are disclosed. Intra prediction exploits the spatial correlation within a picture or within a picture region. In practice, a picture is divided into blocks and the intra mode prediction is performed on a block basis. In newer coding systems, multiple intra coding modes such as Vertical mode, Horizontal mode, DC mode and Diagonal mode, have been used to improve the coding efficiency of intra coding. Furthermore, a Luma_mode has also been used in intra prediction of chroma component to further improve the performance in the High Efficiency Video Coding (HEVC) standard being developed. However, the mode selection information for intra prediction has to be conveyed to the decoder for proper operation. Spatial features in a picture often exist in both luma and chroma components. The intra luma prediction mode and intra chroma prediction mode will have high probability to be the same. Accordingly, an embodiment according to the present invention adaptively assigns variable length codes to a set of mode symbols associated with intra chroma prediction by assigning a shortest code to the Luma_mode. Luma_mode not only can be the best luma mode of the corresponding luma block but also can be selected from several corresponding luma modes. The maximum length of chroma prediction codes is decreased by one bit when Luma_mode is equal to one of frequent modes. The coding efficiency of arithmetic coding of chroma prediction codes is further improved by selecting the context upon neighboring blocks.
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