Simplified search algorithm for explicit wedgelet signalization mode in 3D-HEVC

As the latest 3D video coding standard, 3D High Efficiency Video Coding (3D-HEVC) achieves efficient coding. Depth coding plays an important role in 3D-HEVC. For better prediction of edges in depth maps, new depth intra modes were proposed, such as Depth Modeling Modes (DMMs). DMM Mode 1, namely explicit wedgelet signalization mode, can improve the performance of synthesized views, but leads to unaffordable encoding computation complexity. In this paper, a simplified search algorithm for explicit wedgelet signalization mode is proposed to predigest the complex search process. First, the proposed algorithm only searches the partition patterns in a limited set based on edge detection in the coarse search stage, since the separation line in the best matching pattern should be similar to the edge in an actual depth prediction unit (PU). Then, a wide range of refinement is implemented to guarantee the coding performance. In fact, up to 24 refinements are tested to provide accurate prediction in the refinement process. Experimental results show that considerable encoding time saving is achieved with negligible performance loss. For all intra test cases, the proposed algorithm achieves an average encoding time saving of 75% for DMM Mode 1 with negligible bitrate increase on synthesized views, compared with the default coarse-refinement algorithm in HTM.