Rate-Distortion Optimal Depth Maps in the Wavelet Domain for Free-Viewpoint Rendering

We consider the problem of estimating and encoding depth maps from multiple views in the context of 3D-TV with free-viewpoint rendering. We propose a novel codec based on the Rate-Distortion (RD) optimization of the depth-image-based representation (DIBR) in the wavelet domain. The rate constraint enforces the piecewise smoothness of the depth map, which improves the reliability of its estimation. We propose an efficient optimal solution for the joint estimation and coding of the depth map using dynamic programming along the tree of wavelet coefficients. It also provides an automatic bitrate allocation between images and depth maps. Experiments on real data show that the wavelet approach can improve RD performances over a state-of-the-art technique that uses quadtrees.