Efficient Speckle Noise Filtering of SAR Images

Abstract

Any classification process using SAR images presupposes the reduction of multiplicative speckle noise, since the variations caused by speckle make it extremely difficult to distinguish between neighboring classes within the feature space. Therefore, several adaptive filter algorithms have been developed in order to distinguish between them. These algorithms aim at the preservation of edges and single scattering peaks, and smoothe homogeneous areas as much as possible. This task is rendered more difficult by the multiplicative nature of the speckle noise; the signal variation depends on the signal itself. In this paper, LEE (Lee 1980) and R-LEE (Lee 1981) filters using local statistics, local mean and variance, are applied to RADARSAT SAR images. Also, a new method of speckle filtering, EPOS (Edge Preserving Optimized Speckle) (Hagg & Sties 1994) filter based on the statistical properties of speckle noise is described and applied. And then, the results of filtering SAR images with LEE, R-LEE and EPOS filters are compared with mean and median filters.