Lossless compression of color-quantized images using block-based palette reordering

Abstract

It is well-known that the lossless compression of color-indexed images can be improved if a suitable reordering of the palette is performed before encoding the images. In this paper, we show that, if this reordering is made in a block basis, then further compression gains can be attained. Moreover, we show that the use of block-based palette reordering can outperform a previously proposed block packing procedure. Experimental results using a JPEG-LS encoder are presented, showing how different reordering methods behave. © Springer-Verlag 2004.