SAR Image Despeckling in the Undecimated Contourlet Domain: A Comparison of Lmmse and Map Approaches

In this paper, we propose an extension of two despeckling algorithms, proposed to denoise SAR images and based on the undecimated separable wavelet transform, to work with the nonsubsampled contourlet transform (NSCT). The NSCT is a powerful and versatile nonseparable transform that allows a multiresolution and directional representation to be achieved. The SAR signal is modeled as affected by a multiplicative noise. The noise-free NSCT coefficients are estimated from the observed ones according to either the maximum-a-posteriori (MAP) or the linear minimum mean square error (LMMSE) criterion. The results show that the proposed de-speckling algorithms highly benefit from the fact of working into a multiresolution and multidirectional domain.