Constrained Wavelet Packets for Tree-Structured Video Coding Algorithms

We propose a wavelet packet (WP) algorithm with a constrained Rate-Distortion optimization which makes it suited to subsequent tree-structured coding such as with the Set Partitioning in Hierarchical Trees (SPIHT) algorithm. Traditional WP optimization techniques neglect information about the structure of the lossy part of the compression scheme. Such information, though, can help guide the optimization procedure so as to result in viable and beneficial WP structures. The simple wavelet transform (i.e., octave-band) lends itself to simple tree-shaped spatial relations which can then be used to define zero-trees. But input images have different frequency distributions and an adaptive transform such as WP is bound to be more efficient on an image-by-image basis.