Perceptually adaptive rate-distortion optimization for variable block size motion alignment in 3D wavelet coding

A novel content adaptive rate-distortion optimization scheme has been proposed. The scheme can effectively distinguish texture regions, edge regions and flat regions using a directional field technique. Since the human visual system (HVS) perceives distortions more easily near edges and in flat regions, distortion reduction is more important in those regions than the bits it consumes to code the motion information. Adaptive rate-distortion optimization is carried out by adjusting the Lagrangian multiplier so that small values are assigned to edge and flat regions and large values to the random texture region. The proposed scheme has been tested in the scalable video coding (SVC) reference codec by Microsoft Research Asia (MSRA) (Xu, J. et al., ISO/EEC JTC/WG11 M10569, S05, 2004). Experimental results show that the accuracy of motion alignment in visually important regions is greatly improved in the temporal transform step of 3D wavelet coding and the scheme effectively preserves details in the most perceptually prominent regions for all bitstream layers, with no loss in PSNR.