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A Synthesis-Quality-Oriented Depth Refinement Scheme for MPEG Free Viewpoint Television (FTV)

This paper addresses the problem of refining depth information from the received reference and depth images within the MPEG FTV framework. An analytical model is first developed to approximate the per-pixel synthesis distortion (caused by depth-image compression) as a function of depth-error variances, intensity variations, ground-truth depth and virtual camera locations. We then follow the model to detect unreliable depth pixels by inspecting intensity gradients and to refine their values with a candidate-based block disparity search. Additional side information is transmitted to make both operations robust against compression effects. Experimental results show that our scheme offers an average PSNR improvement of 1.2 dB over MPEG FTV and consistently outperforms the state-of-the-art methods. Moreover, it can remove synthesis artifacts to a great extent, producing a result that is very close in appearance to the ground-truth view image.