Down-/up-sampling based depth coding by utilizing interview correlation

In depth-based 3D video compression, a framework that down-samples a depth map before encoding and up-samples the depth map at the decoder has shown more high coding efficiency, where the down- and up-sampling components are key to the coding performance. In this paper, a down-/up-sampling scheme for 3D video coding is developed by making good use of interview correlation. At the encoder, to obtain a uniform distribution of sampled pixels across views, an interlaced down-sampling approach is applied among different views. Then, at the decoder, a three-step up-sampling approach is proposed accordingly. First, sampled pixels in one view are warped to the to-be-up-sampled view based on their disparity vectors. Second, in order not to introduce new values, the warped pixel is further refined or updated by one of its nearest four sampled pixels. Finally, the unknown pixels left are filled with a known pixel around it. Among all the three steps, a winner-takes-all approach is employed to select a pixel with the largest weight which is determined by considering the depth similarity, texture similarity or geometric closeness. Experimental results demonstrate that the proposed scheme can achieve better down-/up-sampling result and improved the coding efficiency, compared with the conventional algorithms, especially for a large sampling scale.