Research On SAR Image Data Compression

SAR (Synthesis Aperture Radar) generates large amounts of data which should be transmitted to ground to do further analysis, processing. The data would easily exhaust the available capacity of downlink or storage system, so there are special interests in SAR image compression. Because of limitation of hardware at early time, people only compressed raw data which exhibits little correlation. Consequently limited compression ratio could be obtained. For the progress of hardware in recent years, people begin to focus on SAR image compression. SAR images are expected to have higher compression ratio than raw data because of higher correlation in SAR images. SAR image compression is a key technique in SAR system which can help to reduce the requirement of downlink capacity as well as storage. Research work on SAR image compression plays an important role in the design of SAR system, especially space-borne SAR system. In this thesis, we firstly introduce the background of SAR image compression and the aim of this research work. Then we discuss general compression techniques, especially those that are used in our proposed algorithms. In chapter 3 we discuss the correlation in SAR images and the model of speckle. In chapter 4, two algorithms are proposed for complex SAR image compression both making use of the characteristics of SAR images. In chapter 5, we discuss modern wavelet-based image compression algorithms and propose a wavelet-based SAR image compression algorithm working under low bit-rate.