Efficient wedgelet pattern decision for depth modeling modes in three-dimensional high-efficiency video coding

The three-dimensional (3-D) video extension of high-efficiency video coding is an emerging coding standard for multiple-view-plus-depth that allows view synthesis for multiple displays with depth information. In order to avoid mixing between the foreground and background, the depth discontinuities defined at the object boundary should be retained. To solve this issue, a depth intramode, i.e., the depth-modeling mode (DMM), is introduced in 3-D-high-efficiency video coding as an edge predictor. The test model HTM 8.1 includes DMM1 and DMM3. However, the mode-decision strategy of DMM increases the complexity drastically. Therefore, we propose a fast DMM1 decision algorithm that estimates sharp edges by a subregional search method. The optimal wedgelet pattern of DMM1 is then searched only in the most probable region. Additionally, another fast method is raised to skip DMM3 when mismatch occurs between the depth prediction unit (PU) and its colocated texture PU. Simulation results show that the proposed algorithm has slightly better performance in terms of complexity reduction compared with the wedgelet-pattern-reducing algorithm from the literature while better maintaining the coding performance. In addition, the proposed algorithm has a performance similar to that of an existing DMM-skipping algorithm. Moreover, it could be integrated with that category of algorithms for additional time savings.