说明：  matlab实现对SAR图像进行Lee、Frost、Kuan滤波，并且计算峰值信噪比、等效视数等评价指标，只需要改图像名就可以运行
(MATLAB realizes Lee, frost and Kuan filtering for SAR image, and calculates the evaluation indexes such as peak signal-to-noise ratio and equivalent number of views, which can be run only by changing the image name)