此代码是关于高频强调滤波。利用高通滤波器削弱傅里叶变换的低频而保持高频相对不变点，这样会突出图像的边缘和细节，使得图像边缘更加清晰。但是由于高通滤波器偏离了直流分分量，从而把图像的平均值降低到了0,。一种补偿方法是给高通滤波器加上一个偏移量。通过算法达到目的。-High-Frequency Emphasis Filtering.High-pass filers zero out the DC term (the value at the center of a high-pass filter mentioned in our lecture is 0 in the frequency domain), thus reducing the average value of an image to 0. Then we introduce an approach used to compensate for this is to add an offset to a high-pass filter.