Visual compander in wavelet-based image coding

In this paper, we propose a new wavelet-based image coding scheme which exploits jointly the statistical redundancy and the irrelevance properties of the human visual system. We first establish the visibility threshold model in the wavelet transform domain. Then, a visual compander is designed so that the output data of the compressor is visually uniform. A uniform quantizer and entropy coding are used for the output data. Experiment results show that our image coding scheme provides slightly improved visual quality without no degradation in PSNR, compared with the result of Shaprio's (1993) scheme.