Mean-Shift-Based Speckle Filtering of Polarimetric SAR Data

The mean shift algorithm, which uses a moving window and utilizes both spatial and range information contained in an image, is widely employed in digital image filtering and segmentation. However, because of the large dynamic range of synthetic aperture radar (SAR) images, applying the conventional mean shift algorithm directly to SAR image filtering will not produce meaningful results. This paper proposes an adaptive variable asymmetric bandwidth selection approach to be used in a newly derived generalized mean shift algorithm. The proposed mean shift algorithm is very versatile and can be used for SAR and polarimetric SAR (PolSAR) image filtering directly without any preprocessing steps. Monte Carlo-simulated PolSAR data are used to demonstrate the effectiveness of the proposed algorithm in speckle filtering by comparing it with other filters. Experimental Synthetic Aperture Radar (ESAR) L-band and Radarsat-2 C-band PolSAR data are used to evaluate its ability to preserve the polarimetric information of PolSAR data. The effects of initial value estimating and multilook processing on the filtered results are discussed at the end of this paper.