New intra luma prediction mode in H.264/AVC using collocated weighted chroma pixel value
Ik-Hwan Cho, Jung-Ho Lee, Woong-Ho Lee, Dong-Seok Jeong · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2006
Intra prediction in H.264/AVC uses 9 modes in 4×4 luma block, 4 in 16×16 luma and 8×8 chroma blocks. Intra prediction modes utilize similarity of current macroblock with pre-encoded neighboring macroblocks and directionality of image in pixel domain. Therefore its coding efficiency in H.264/AVC is improved compared to the conventional video codecs such as MPEG-2 and MPEG-4. However coding efficiency in intra-coded frame is much lower compared to that of inter slice since the intra prediction modes use only limited neighboring macro blocks and then to obtain good matched reference block image using intra prediction may be more difficult than inter prediction. Therefore for higher coding efficiency, it is very important to get good matched prediction block in a given envirionment. In general video codec which uses general 4:2:0 YCbCr format, overall coding efficiency issue is mainly focused on luma relative to chroma components. In this paper, we propose additional intra luma prediction mode using collocated chroma pixels and weight values. The proposed method utilizes collocated chroma macroblocks as reference image for more efficient intra luma prediction.