Effective CU size decision algorithm based on depth map homogeneity for 3D-HEVC inter-coding

High efficiency video coding standard-based 3D video (3D-HEVC) is an extension of high efficiency video coding standard (HEVC) to improve the efficiency of the multiview video plus depth (MVD). In 3D-HEVC inter-coding, The quad-tree structure of coding unit (CU) partition supports different sizes from 64×64 to 8×8, namely, CU sizes. The CU partitioning process achieves the highest coding efficiency, but it brings an extremely large encoding time and a large computational complexity occurs which limits the 3D-HEVC encoder from practical applications. In this paper, an early termination of CU size is proposed for dependent views in 3D-HEVC depth map encoding. The proposed algorithm based on homogeneity classification of a depth map CU using an unsupervised classification algorithm. Based on the classification results, the proposed method determines whether a depth CU must be or not be split into smaller sizes. Experimental results show that the proposed approach can achieve a reduction of computational complexity for depth map encoding with a negligible reduction of coding performance.