An extension of multi-look polarimetric whitening filter for speckle reduction in polarimetric SAR images

With the availability of fully polarimetric SAR data, there is the possibility to reduce the image speckle polarimetricly. Novak et al. has proposed a polarimetric whitening filter (PWF) that processes the single-look polarimetric SAR data to generate an intensity image with minimum speckle. And the PWF has been extended to the multi-look case to form a multi-look PWF (MPWF). The drawback of the PWF and MPWF is that they do not preserve the polarimetric information. In this paper the authors present an extended MPWF (EMPWF). Based on a polarimetric multiplicative speckle model, the EMPWF combines the texture estimation produced by the original MPWF and the adaptively estimated polarimetric covariance to generate a filtered covariance matrix. It can now preserve the polarimetric information while removing the speckle, and is thus a fully polarimetric speckle filter. Experimental results with NASA/JPL L-band 4-look polarimetric SAR data demonstrate the effectiveness of the EMPWF.