An Enhanced Weighted Median Filter for Noise Reduction in SAR Interferograms

In this paper, we describe a new filtering method based on the weighted median filter and the Lopez and Fabregas noise reduction algorithm operating in the wavelet domain. It is developed for the reduction of the impulse phase noise in synthetic aperture radar interferograms (InSAR). Our contribution to the classic weighted median filter consists of using the InSAR coherence map to generate the weights. While the developed approach prioritizes the high-coherence areas to compute the median filter outputs, the computation of the weights depends on the coherence values within the used window. The developed algorithm is then tested on a simulated data set as well as a set of Radarsat-2 raw data and ERS-2 SLC images acquired over the region of Mahdia and Ben Guerden respectively in Tunisia. The results validation is considered through computing the unwrapped phase of the filtered interferogram by using the SNAPHU algorithm.