Adaptive motion-estimation-mode selection for depth video coding

An effective representation of 3D video in future 3D-TV systems consists of monoscopic video (colour component) and associated per-pixel depth information (depth component). As depth component indicates relative distance between objects within the scene and a camera, pixel values change not only when objects move in vertical and horizontal directions but also when they move in a depth direction. Instead of predicting motion of objects in two directions as appearing in traditional video codecs, three-dimensional block matching (3D-BM) achieves more accurate motion estimation in depth video coding. However overall performance of 3D-BM exceeds that of the traditional two-dimensional block matching (2D-BM) only at high bit rate. In this paper, an adaptive 2D-3D BM selection algorithm is introduced to compromise performance of 2DBM and 3D-BM. The Lagrangian optimisation algorithm is applied to select motion estimation mode at a block level. The experiment results reveal that the proposed adaptive motion-estimation-mode selection can improve the performance of 3D-BM at low bit rate while advantages of 3D-BM are preserved at high bit rate.