Optimum dithering for scalar quantization of image subband

A joint optimization method for design of filter banks and related dithered quantizers by using time-domain formulation of filter banks is provided. Mathematical analysis and experiments show that in image subband coding by appreciate choice of synthesis filter bank and dithering, it would be possible to replace signal-dependent artifacts with signal- independent white noise. This process improves the perceptual quality of reconstructed image, especially at low bit-rates and makes it more practical for a noise-removal algorithm to remove the output noise. Experiment results illustrate the effectiveness of dithering for lower frequency bands and modification of synthesis filter bank for higher frequency bands.