Homomorphic wavelet-based statistical despeckling of SAR images

S. Solbo, T. Eltoft
2004 IEEE Transactions on Geoscience and Remote Sensing  
In this paper, we introduce the homomorphic 0-WMAP (wavelet maximum a posteriori) filter, a wavelet-based statistical speckle filter equivalent to the well known 0-MAP filter. We perform a logarithmic transformation in order to make the speckle contribution additive and statistically independent of the radar cross section. Further, we propose to use the normal inverse Gaussian (NIG) distribution as a statistical model for the wavelet coefficients of both the reflectance image and the noise
more » ... and the noise image. We show that the NIG distribution is an excellent statistical model for the wavelet coefficients of synthetic aperture radar images, and we present a method for estimating the parameters. We compare the homomorphic 0-WMAP filter with the 0-MAP filter and and the recently introduced 0-WMAP filter, which are both based on the same statistical assumptions. The homomorphic 0-WMAP filter is shown to have better performance with regard to smoothing homogeneous regions. It may in some cases introduce a small bias, but in our studies it is always less than that introduced by the 0-MAP filter. Further, the speckle removed by the homomorphic 0-WMAP filter has statistics closer to the theoretical model than the speckle contribution removed with the other filters. Index Terms-Homomorphic filtering, normal inverse Gaussian (NIG), synthetic aperture radar (SAR), speckle, speckle filtering, wavelet.
doi:10.1109/tgrs.2003.821885 fatcat:z43wbcu6ifb23gbp6i7kfkwnni