Multiresolution edge adaptive algorithm for low bit rate image coding

The problem of quantizing sub-images of a multiresolution image decomposition while preserving edges is considered. For this purpose, we propose a coding algorithm which exploits the spatial locations of coefficients within scales. This algorithm, we call edge adaptive quantization, preserves edges while smoothing elsewhere once the different significant coefficients are determined. Spatial adaptation is introduced by considering a new spatially constrained scalar quantizer based on Markov random fields. A criterion based on new spatial models is developed as well as an optimization procedure selecting the optimal quantizer in the distortion-spatial constraints sense. This algorithm is dedicated to low bit rate coding.