Planar representation for intra coding of depth maps

In this paper, an intra coding method is proposed aiming to efficiently code the smooth regions in the depth map images. One of the characteristics of typical depth map images is that they contain large gradually changing smooth areas. Traditional block based transform coding algorithms are causing blocking artifacts for this type of regions. Instead of using transform coding, the proposed method utilizes piecewise linear planar representations to code the smooth areas in the depth map picture. The piecewise linear representation for a block is obtained using the already decoded pixels neighboring the block and the block´s bottom-right sample. The experimental results show that significant compression improvement can be achieved with depth sequences containing smooth regions. By visual inspection, it is also shown that the blocking artifacts are significantly reduced.