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为了有效抑制SAR强度图像中的相干斑噪声,提出一种改进Sigma滤波并结合GammaMAP滤波的空域相干斑抑制方法。首先利用阈值判断法判断并保留强点目标,然后结合SAR图像分布模型和MMSE准则判断Sigma区间,其中可以根据图像局部统计特性自适应调整窗口尺寸,最后选择Sigma区间内像素进行Gamma MAP滤波。实验结果表明:对于星载和机载SAR图像,在相干斑噪声抑制和边缘纹理细节信息保持方面,该方法较其他常用的空域相干斑抑制方法具有明显的优越性,能极大地提高SAR图像判读和目标识别能力。
In order to effectively suppress the speckle noises in the SAR intensity image, a modified method of spatial filtering with GammaMAP filtering is proposed. Firstly, the threshold judgment method is used to judge and retain the strong point target. Then the Sigma interval is judged according to the SAR image distribution model and the MMSE criterion. The window size can be adaptively adjusted according to the local statistical characteristics of the image. Finally, the pixels in the Sigma interval are selected for Gamma MAP filtering. The experimental results show that this method has obvious advantages over other commonly used methods of space-domain speckle suppression in the suppression of speckle noise and preserving details of edge texture for spaceborne and airborne SAR images, which can greatly improve the SAR image interpretation And target recognition ability.