A lossless compression algorithm for color-indexed images using adaptive palette reordering

In this paper, an adaptive palette reordering method is proposed to reshape the statistical properties of the color index map of a color-indexed image with a dynamic palette. The proposed method extracts information from both the palette and the color index map to achieve the objective. It reduces the zero-order entropy of the image and removes the spatial correlation among pixels significantly. The compression performance of JPEG-LS can be significantly improved when the proposed method is used. An even better compression performance can be achieved when being compatible with JPEG-LS is not the concern.