Simple, high performance lossless image compression

We present a two-part method for lossless image compression: the first is a simple transformation based on JPEG-LS and the second is the use of a general purpose file compressor such as gzip, bzip2 or rk. The transformation is invertible and uses only integer arithmetic. It achieves no compression directly; however, on some images, it can significantly reduce the entropy. The gzip, bzip2, and rk compressors, with and without the transformation, are tested against JPEG-LS on a standard data set. Overall rk (both with and without the transformation) is best. Furthermore, by combining the various algorithms, we obtain compression that is 15% better than JPEG-LS alone