Adaptive vector quantization for raw SAR data

This paper proposes an adaptive vector quantization scheme designed for spaceborne raw SAR data compression. This approach is based on the fact that spaceborne raw data are Gaussian distributed, independent, and quite stationary over an interval (in both azimuth and range) which depends on SAR system parameters. The block gain adaptive vector quantization (BGAVQ) is a generalization of the block adaptive quantization (BAQ) algorithm to vectors. It operates as a set of optimum vector quantizers (designed by the LBG algorithm) with different gain settings. The adaptation is particularly efficient since, for a fixed compression ratio, the same codebook is used for any spaceborne SAR data. Results on simulated and real images, for data rate of 1.5 to 2 bit/sample, have confirmed the expected performance of the BGAVQ algorithm