Depth map-sequence coding algorithm based on fractal

Depth map compression is the crucial technology in three dimentional video (3DV) coding system. To obtain high compression efficiency and low encoding complexity for depth map-sequence, this paper proposes a novel coding algorithm for depth map-sequence based on fractal. This applicable scheme for depth map-sequence coding is proposed by adequately exploiting local similarity between adjacent frames in depth map-sequence and combining intra-prediction method in H. 264. In the proposed scheme, the I frame in depth map-sequence is encoded by adopting intra-prediction structure in H. 264, while the P frame is encoded by fractal compression method. Firstly, the theoretical basis of fractal coding is presented. Then, a new motion-vector-field-based adaptive hexagon search algorithm, which is applicable to fractal coding, is proposed by improving unsymmetrical multi-level hexagon search (UMHexagonS) method. Finally, the P frame prediction structure based on fractal in depth map-sequence coding is formed. Experimental results indicate that the proposed coding system can improve the overall performance of the H. 264 coding system with an average Bjøontegaard delta peak signal-to-noise ratio (BDPSNR) gain of 3.54 dB and an average Bjøontegaard delta bit rate (BDBR) reduction of 40.98%. Furthermore, the computational complexity is reduced and the entire encoding time on average is saved by 85.27%. In addition, the proposed algorithm shows certain advantages compared with other international representation methods in this field.