KALMAN FILTER FOR REMOVAL OF SCALLOPING AND INTER-SCAN BANDING IN SCANSAR IMAGES

Spaceborne synthetic aperture radar (SAR) plays more and more important role in Earth observation science, especially with ScanSAR mode which provides wide-swath coverage with moderate resolution. However, scalloping and inter-scan banding (ISB) are two major artifacts, which signi cantly degrade the quality of ScanSAR images. In this paper, a novel technique for removal of scalloping and ISB in ScanSAR images is proposed. Scalloping and ISB artifacts are modeled by two-dimensional gain and o set parameters varying as function of both azimuth time and range position. The gain and o set parameters can be split into azimuth and range components. The variations of gain/o set with respect to azimuth and range positions would represent scalloping and ISB artifacts respectively. In the proposed technique, recursive and minimum mean square error (MMSE) estimates of azimuth gain/o set parameters are found out by using Kalman lter for each azimuth location in a subswath by considering corresponding range samples as observation vector. Subsequently, range gain/o set parameters causing ISB artifacts are estimated by using Kalman lter for each range positions by considering azimuth samples as observation vector. The MMSE estimates of gain/o set parameters are used to directly remove scalloping and ISB artifacts. The proposed scheme was applied on simulated as well as calibrated real ScanSAR images. The experimental results exhibited the potential of proposed technique to be used as post processing tool for enhancing ScanSAR image quality.