Dinei Florencio and Patrice Simard
Many image coders map the input image to a transform domain, and encode coefficients in that domain. Usually, encoders use previously transmitted samples to help estimate the probabilities for the next sample to be encoded. This backward probability estimation provides a better PDF estimation, without need to send any side information. In this paper we propose a new method of encoding that goes one step further: besides past samples, it also uses information about the current sample in computing the PDF for the current sample. Yet, no side information is transmitted. The initial PDF estimate is based on a Tarp filter, but probabilities are then progressively refined for nonzero samples. Results are superior to JPEG2000, and to bit-plane Tarp.