Vector set partitioning with classified successive refinement VQ for embedded wavelet image and video coding
The set partitioning in hierarchical trees (SPIHT) approach for still image compression proposed by Said and Pearlman (see IEEE Transactions on Circuits and Systems for Video Technology, vol.6, no.3, 1996) is one of the most efficient embedded gray image compression schemes to date. The algorithm relies on a very efficient scanning cum bit-allocation scheme for quantizing the coefficients obtained by a wavelet decomposition of an image. We adopt this scheme to scan vectors of wavelet coefficients, and use successive refinement VQ techniques with staggered bit-allocation to quantize several wavelet coefficients at once. The new scheme is named VSPIHT (vector SPIHT). We present some coding results comparing VSPIHT to the scalar counterpart in the mean-squared-error sense. The method readily generalizes to color images and video where the vector-based approach makes more sense. We present the coding results on intra frames of QCIF sequences as compared against H.263.