中文说明：
这是冈萨雷斯版数字图像处理中的几个函数的实现，包括dftfilt, dftuv,hpfilter,imnoise2,improd,希望对你的学习有所帮助
English Description：
This is the Gonzalez version of digital image processing in the realization of several functions, including dftfilt, dftuv, hpfilter, imnoise2, improved, I hope to help you learn