Bit allocation algorithm for codebook design in vector quantisation fully based on human visual system nonlinearities for suprathreshold contrasts

A fully perceptual oriented approach for codebook design in the vector quantisation of images for compression purposes is presented. The proposed algorithm not only exploits the usually considered dependence on frequency of the human eye but also makes use of the nonlinear behaviour of the visual system for suprathreshold contrasts. From experimental data of human contrast incremental thresholds of sinusoidal grids, we present a perceptually optimal information allocation function. Simulations show that by introducing perceptual contrast nonuniformities a more efficient bit allocation is attained than that for the JPEG-like contrast uniform algorithm