Wavelet-based image coder with entropy-constrained lattice vector quantizer (ECLVQ)

Abstract

This paper presents an algorithm that jointly optimizes a lattice vector quantizer (LVQ) and an entropy coder in a subband coding at all ranges of bit rate. Estimation formulas for both entropy and distortion of lattice quantized subband images are derived. From these estimates, we then develop dynamic algorithm optimizing the LVQ and entropy coder together for a given entropy rate. Compared to previously reported min-max approaches, or approaches using asymptotic distortion bounds, the approach reported here quickly designs a highly accurate optimal entropy-constrained LVQ. The corresponding waveletbased image coder also has better coding performance compared to other subband coders that use entropy-constrained LVQ, especially at low bit rates.