Sparse dyadic mode for depth map compression

In order to enable new video applications such as 3DTV and free-viewpoint video, new data formats including both 2D video sequences and corresponding depth map sequences have been proposed. One major characteristic making the depth maps different from video frames is that they typically consist of homogeneous areas separated by sharp edges representing depth discontinuities. Another characteristic of depth map sequences is that the edges exhibit quite similar boundary behaviors as the edges in the corresponding video frames. In this paper, we propose a novel sparse dyadic mode in the design of an efficient depth map compression algorithm through appropriately exploiting these characteristics. With sparse representations of depth blocks and effective reference of edge information from the corresponding video frames, sparse dyadic mode can achieve up to 1.5 dB gain on rendering quality as compared to depth sequences coded using MVC at the same bitrate.