Polarimetric Speckle Filters For SAR Data

Abstract

The usual polarimetric speckle filters ophally combine the polarization channels into a single image (Novak and Burl) or only restore the radiometric information (Lee et al.), i.e. the 3 Ihh, I, Ihv intensities in the r e c i p r d case. So the phase differences and the polarization channel correlation coefficients are not restored in the fdtered data. This implies a loss of information compared to the initial data, which contain in the reciprocal case 5 independent real parameters plus 1 absolute phase for 1 look scattering matrix format and 9 independent parameters for multi-look data. In this paper we develop a polarimetric minimum mean square error (MMSE) filter and a polarimetric maximum a posteriori (MAP) filter. For each pixel, one obtains on output of the filtering process either a complex "unspeckled" scattering matrix and 3 local correlation coefficients between the polarization channels for 1 look, or the 9 real parameters of the covariance matrix for multi-look images.