编程实现灰度图像的频域滤波算法。使用Matlab实现不延拓和延拓两个版本。对于延拓和不延拓版本，在理想低通滤波器、巴特沃斯低通滤波器和高斯低通滤波器上比较两者的区别；对于延拓版本，比较不同参数设置对上述三种滤波器滤波结果的影响。(Program to realize the filtering algorithm of gray image in frequency domain. Matlab is used to realize two versions of no extension and extension. For the extension version and the non extension version, the differences between the ideal low-pass filter, Butterworth low-pass filter and Gauss low-pass filter are compared; for the extension version, the effects of different parameter settings on the above three filter results are compared.)