Improving the JPEG-LS compression of images with locally sparse histograms

In this paper, we propose a preprocessing tech- nique that is capable of improving the compression of images that have locally sparse intensity histograms. In this case, (global) off-line histogram packing may be unsuitable. How- ever, by reducing the size of the symbol-set used by the packing procedure, we are able to attain globally better results, being some of them quite dramatic.