Better codebooks and faster convergence in VQ design

We approach the problem of designing the VQ codebook from a different point of view: after having evaluated a priori the effects produced by any possible single vector redistribution among clusters, we choose and apply the least distortion one. This way of looking at the problem with "new eyes", though quite immediate and simple in its formulation, provides powerful tools for devising a variety of new algorithms and procedures. The intrinsic property of the algorithm, assuring fast convergence in terms of number of iterations, has been fruitfully combined with a suitable speedup procedure leading to a drastic complexity reduction. The performance, measured within applications to image coding, prove the algorithm to be up to 50 times faster than the GLA method increasing the peak signal to noise ratio (PSNR) at knee of nearly 1 dB.