Fast rate-distortion estimation and optimization for wavelet video coding

The motion compensated- and difference- residual frames of a typical video sequence displays strong energy localization in the spatial domain. SPIHT expends many bits describing the location of the areas of energy concentration, and at low rates, these bits, which do not contribute to a PSNR increase, are wasteful. The scheme to be described avoids this wastage by performing local rate-distortion estimation and spatial bit assignment to achieve global PSNR optimality. The key to the algorithm is an extremely fast and accurate R-D estimation scheme, which permits this algorithm to operate in real-time.