Speckle Noise Filtering in SAR Images by MAP Approach
Nelson D. A. Mascarenhas, L.F. Costa, F.N.S. Medeiros · 1999
. The main purpose of this work is to study and implement the Maximum a Posteriori (MAP) filter to suppress speckle in SAR images. This type of noise is due to the coherent nature of the radiation used in Synthetic Aperture Radar and the interference between the waves reflected from the imaged area. This paper is based on the multiplicative model and considers several different densities to describe the "a priori" knowledge. 1 Introduction SAR imaged areas are corrupted by speckle noise, which degrades images formed by laser beams, radar (SAR), ultrasound etc. Speckle is caused by the interference between waves reflected from microscopic scattering through the terrain, in the particular case of SAR images. This kind of noise can be modeled in terms of a random walk in the complex plane and, in the case of a large number of scatters within the resolution cell (fully developed speckle), the real and imaginary parts of the resulting complex field are Gaussian random variables . It h...