Robust Polarimetric SAR Despeckling Based on Nonlocal Means and Distributed Lee Filter

This paper presents a nonlocal Lee (NL-Lee) filter for polarimetric synthetic aperture radar despeckling. In the proposed NL-Lee filter, a kind of hybrid patch similarity measure is constructed by combining together the structure similarity introduced by the nonlocal means (NLM) filter and the homogeneity similarity introduced by the Lee filter, which works in a distributive way. This combination leads to two important advantages for the proposed nonlocal filter. One is the improved robustness to the NLM parameters such as patch size and search neighborhood size, since the patch regularity assumption can be enhanced by the introduced hybrid patch similarity; the other one is the better performance tradeoff between speckle removal and detail preservation, because of the good balance between structure similarity and homogeneity similarity obtained by the framework of the proposed NL-Lee filter. Experimental results are given to demonstrate its competitive denoising performance.