Edge-adaptive depth map coding with lifting transform on graphs

We present a novel edge adaptive depth map coding based on lifting on graphs. The transform is localized, of low complexity, and guarantees perfect reconstruction as long as a proper predict-update split is defined. During the transform process, data in the prediction set are predicted by data in the update set; the prediction errors are then stored for encoding. In order to reduce the energy of the prediction residue, we propose to use optimized sampling on graphs to select the update set. Experiments show that the optimized sampling approach achieves better results than the conventional maximum cut based splitting in terms of transform efficiency and reconstruction quality. In addition, performance using the lifting transform is comparable to the state-of-the-art graph based depth map encoder using graph Fourier transform (GFT), which requires high complexity for signal projection.