https://blog.csdn.net/qq_28005905/article/details/97787710?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522162499445316780262534655%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=162499445316780262534655&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduend~default-2-97787710.first_rank_v2_pc_rank_v29_1&utm_term=SAD+python&spm=1018.2226.3001.4187
程序来自这里
DSR就是搜索的范围，k是用于遍历该范围的一个变量，具体可以参考：https://blog.csdn.net/opencv_fjc/article/details/95482437
