Scattering-Based SARBM3D

Abstract

Interpreting synthetic aperture radar (SAR) images may be a very challenging task, even for expert users. One of the main reasons is the multiplicative speckle noise typical of coherent acquisition systems. Therefore, despeckling can be expected to play a key role in the full exploitation of SAR imagery potential. However, even state-of-the-art despeckling algorithms neglect the physical phenomena hidden behind SAR imagery. Image acquisition depends on electromagnetic scattering, which is also at the basis of speckle noise. Taking into account scattering issues into more physical-based despeckling algorithms may only benefit the overall performance. In this paper, we propose a scattering-based (SB) version of the SAR block-matching 3D (BM3D) filter, named SB-SARBM3D. SARBM3D can be arguably considered as one of the most promising and accurate despeckling algorithms, providing a good compromise between speckle reduction and detail preservation. We modify the original algorithm so as to exploit the prior information available on the imaged scene, taken into account based on scattering concepts. The new algorithm is tested in a variety of different and complementary simulated scenarios, and its performance is assessed objectively by means of numerous synthetic parameters. Moreover, comparison with different state-of-the-art despeckling algorithms is performed on some actual SAR images, both inherent to natural and urbanized areas, for subjective evaluation. Thanks to the prior information, SB-SARBM3D outperforms the original algorithm in terms of both speckle reduction and detail preservation. Moreover, it reduces the annoying artifacts introduced sometimes by SARBM3D in homogeneous areas of the image.