The efficiency of perceptual coding in compressing color

images relies on the estimation of perceptual redundancy.

In this paper, a color image coder is proposed for perceptually

lossless image compression which shapes the coding

error as a part of perceptual redundancy. The perceptual

redundancy inherent in each pixel of a color image is

estimated in terms of a triple of values, one for each color

channel, as a detection threshold for distortion.