A Lossless Compression Algorithm for SAR Amplitude Imagery Based on Modified Quadtree Coding of Bit Plane

A lossless compression algorithm for synthetic aperture radar (SAR) amplitude images based on modified quadtree bit-plane coding is proposed. First, a SAR amplitude image is divided into independent bit planes, and then, the probability of bit “0” is computed and compared with the predefined threshold in order to select the optimal block size for each bit plane. Finally, a modified quadtree coding method is adopted to encode each block data. Additionally, the computing method of predefined threshold is also addressed in this letter. The experimental results show that the proposed method outperforms previous methods for all SAR images of the test sets; an average 0.895-bpp decrease in bit rate was observed when compared with JPEG-LS.