L2 versus L∞ criterion in biomedical image compression (mammograms)

Image compression using L^∞-norm and confidence interval criteria was shown to have some advantages with respect to flexibility and accuracy. The improvements are due to a local control of the distortion, which allows some local knowledge on the original signal to be exploited. The coding scheme is flexible and can perform a large variety of coding qualities, including lossless compression. This quality is fixed a priori according to the use of the reconstructed image. This paper studies the advantages of the L^∞-norm coding technique applied to medical imaging (mammography), compared to classical L² norm techniques. The coding scheme is recalled and used to achieve different levels of compression: going progressively and accurately from lossless to near-lossless then lossy compression. Results of experiments conducted on several mammograms are presented. When compared to the classical m.s.e based schemes, this approach is shown to give more flexibility and higher quality of the reconstructed mammograms (especially, microcalcifications)