Sum-of-gradient based fast intra coding in 3D-HEVC for depth map sequence (SOG-FDIC)

As the latest video coding standard for multi-view plus depth video, 3D-HEVC yields high coding efficiency but at the cost of heavy computational complexity. To reduce the computational complexity, a fast intra coding algorithm based on sum-of-gradient criterion for depth map coding in 3D-HEVC, named SOG-FDIC, is proposed in this paper. Based on the observation that DMM modes and smaller partitioning sizes are rarely used in flat region, sum of gradient is presented to determine whether the current block belongs to the flat region so as to skip unnecessary checking of DMMs and smaller partitioning sizes. Experimental results show that the proposed algorithm can save about 21.8% coding time while keeping almost the same coding efficiency and the reconstructed video quality of depth maps and synthesized views, compared with the original 3D-HEVC. Moreover, it has been verified that the proposed method outperforms the state-of-the-art methods.