对一副M*N大小的图像重复使用截频为D0的高斯低通滤波器进行滤波。假设K为滤波次数。并从理论上说明当K足够大时的滤波结果及产生原因-Right an M* N size of the image is repeated using the cutoff frequency for the D0 of a Gaussian low-pass filter for filtering. Assuming K is filtering times. And filtering results when K is large enough and theoretically causes