Edge-preserving intra depth coding based on context-coding and H.264/AVC

Depth map coding plays a crucial role in 3D Video communication systems based on the “Multi-view Video plus Depth” representation as view synthesis performance is strongly affected by the accuracy of depth information, especially at edges in the depth map image. In this paper an efficient algorithm for edge-preserving intra depth compression based on H.264/AVC is presented. The proposed method introduces a new Intra mode specifically targeted to depth macroblocks with arbitrarily shaped edges, which are typically not efficiently represented by DCT. Edge macroblocks are partitioned into two regions each approximated by a flat surface. Edge information is encoded by means of context-coding with an adaptive template. As a novel element, the proposed method allows exploiting the edge structure of previously encoded edge macroblocks during the context-coding step to further increase compression performance. Experiments show that the proposed Intra mode can improve view synthesis performance: average Bjøntegaard bit rate savings of 25% have been reported over a standard H.264/AVC Intra coder.