A novel approach for coding color quantized images

Color images are usually compressed in a luminance-chrominance coordinate space, with the compression performed independently for each coordinate. If such a compression technique is applied to an image using a limited palette, the pixels of the decoded image may take on values beyond those in the original palette. In order to display the decoded image using a limited palette, it must be quantized. In this paper, we present a new approach for the lossy compression of color images with limited palette that does not require color quantization of the decoded image. The algorithm is particularly suited for coding images using an image-dependent palette. The proposed technique restricts the pixels of the decoded image to take values only in the original palette. Thus, the decoded image can be readily displayed without having to be quantized. For comparable quality and bit rates, the proposed technique significantly reduces the decoder computational complexity.