Standard Image Compression for Data Link Transmission

Synthetic Aperture Radar (SAR) is a high-resolution, wide-area, active imaging technique usable in day-night, all-weather conditions. SAR-equipped airborne platforms, including the U-2 fleet, the Joint Surveillance Target Attack Radar System (JSTARS) E-8and unmanned aerial vehicles (UAVs), and spaceborne platforms (satellites and the Shuttle), are rapidly proliferating the volume of data that must be piped over constrained bandwidth wireless links. The problem is exacerbated by an increasing commercialdemand for these scarce spectrum resources and the DoD's desire to maximize the intelligence benefit of the SAR imagery. Tactical needs impose strict time constraints on imagery transmission delays. The push is on to preserve the image phase componentallowing processing such as Interferometric SAR and facilitating Measurement and Signal Intelligence (MASINT) exploitation. A solution is to reduce the transmitted data volume using compression techniques. Popular standards-based compression forelectro-optical imagery is ill-suited for the high dynamic range, speckled, and complex-valued SAR imagery. SRC therefore proposes to develop an innovative compression technique based on the wavelet packet transform that will dynamically adapt to the SARdata source statistical distribution. Our emphasis will be on researching suitable cost metrics and search algorithms yielding compression results that support automated exploitation and human interpretability.Compression of SAR image data using lossyBlock Adaptive Quantization (BAQ) or lossless techniques does not provide the degree of reduction needed to transmit over commonly available wireless link bandwidths (e.g., T-1 = 1.544 Megabits per second). Our compression technology will overcome thiswireless bottleneck with suitable compression ratios, providing benefit to a variety of SAR applications including oil spill monitoring, sea ice monitoring, agricultural classification and assessment, natural resource location, oceanography, topographicalmapping, search and rescue operations, treaty verification, and non-proliferation monitoring.