<title>Comparision of adaptive quadrature mirror filter subband coding systems</title>

Abstract

We investigate high quality coding systems by exploiting both statistical andpsychovisual video signal properties. Source image filtering via Quadrature Mirror Filters (QMF) and quantization of the obtained subbands, seem suitable to exploit both these signal properties. All the investigated QMF filters are separable, non-recursive, and oftwo different types. The first type consists of linear phase filters which allow, after synthesis, exact cancellation of all aliasing, but the overall characteristic of the analysis-synthesis system has amplitudeonly approximately constant The secondtype is constitutedby more sophisticated filters which allow exact signal reconsiruction and, naturally, cancellation of all aliasing; however, the single filters constituting the bank can be nonlinear phase filters. These can be implemented by a lattice structure which induces, and thereby guarantees, perfectreconstruction even ifthelatticeparameters arecoarsely quantized. Uniform quantizers havebeenchosen for all subbands, with DPCM for the lowest frequency band and PCM for the higher frequency bands. Certain quantizer parameters are adapted to the type of filter used. Additional parameters are adaptively adjusted according to the statistics of the subbands. This work aims at finding a satisfactory compromise between the characteristics of the QMF filter bank and those of the coders.