CQF FILTER BANKS MATCHED TO SIGNAL STATISTICS

The Karhunen-Loeve transformation (KLT) is the best one among all orthogonal transformations of a given size from the point of view of the coding gain. When bits have been optimally allocated to transform coefficients, the distortion is only a function of the product of the transform coefficient variances. The KLT minimizes this product under the constraint of a given sum of these variances. It is optimum from both points of view of coding pin maximization and zonal sampling. The same objective can be pursued with subband systems. The analysis filter bank can be chosen so as to minimize the product of subband variances. That question will be dealt with in the case of a 2-band system. It will be shown that CQF filters banks fulfilling the criterion of minimum product of subband variances are also optimum from the two points of view mentioned for the KTL.