SAR Image Despeckling Based On Nonlocal Means Filter

Synthetic Aperture Radar (SAR) is a kind of microwave band coherent radar system. But its inherent imaging mode makes the SAR image inevitably produce a coherent speckle noise (speckle), which seriously influences the quality of the image. It brings difficulties to Target recognition and feature extraction. Therefore, the reduction of speckle became the key step in processing SAR image before the image processing and image analysis. It is widely accepted that speckle of SAR image is multiplicative noise. For removing such noise, firstly, the image of the multiplicative noise is transformed into additive noise. This paper attempts to focus on the use of multiresolution Non-Local means to the additive noise of image. Then the exponentiation is used to the processed image, and can gained suppress speckle of image. Specifically, this paper contains three aspects as follows:Firstly, according to existing SAR image despeckling of disadvantage, speckle denoising with multiresolution bilateral filtering is introduced. First, we use wavelet decomposition to the logarithmic conversion image, when the image is decomposed into high and low frequencies. Then the two parts can make use of seting thresholds and bilateral filtering methods.Secondly, based on Non-Local means of SAR images is introduced.we use the non-local mean filtering method for the image of additive noise.Thirdly, inspired by multiresolution bilateral filtering, a multiresolution Non-Local means is proposed and applied to the despeckling of the SAR image.The data analysis and the simulation experiments of the paper in each section show: the speckle denoising algorithms of SAR image and retaining the edge have certain advantages.