Unequal loss protection: Graceful degradation of image quality over packeterasure channels through forward error correction

We present the unequal loss protection (ULP) framework in which unequal amo unts of forward error correction are applied to progressive data to provide graceful degradation of image quality as packet losses increase. We develo p a simple algorithm that can find a good assignment within the ULP framewo rk. We use the Set Partitioning in Hierarchical Trees coder in this work, b ut our algorithm can protect any progressive compression scheme. In additio n, we promote the use of a PMF of expected channel conditions so that our s ystem can work with almost any model or estimate of packet losses, We fmd t hat when optimizing for an exponential packet loss model with a mean loss r ate of 20% and using a total rate of 0.2 bits per pixel on the Lenna image, good image quality can be obtained even when 40% of transmitted packets ar e lost.