Near-lossless compression of coherent image data

Near-lossless compression, yielding a strictly bounded reconstruction error, is extended to preserve the radiometric resolution of data produced by coherent imaging systems. A noncausal DPCM, based on the rational Laplacian pyramid (RLP), recently introduced by the authors for despeckling, is adjusted to this purpose. The baseband icon of the RLP is DPCM encoded, the intermediate layers are uniformly quantized, and the bottom layer is logarithmically quantized. As a consequence, the relative error, i.e., pixel ratio of original to decoded image, can be strictly bounded by the quantization step size of the bottom layer of the RLP.