Midpoint Filtering for Noise Reduction

Opencv写的空间滤波包括最大最小中值滤波等等，借鉴数字图像处理matlab版page117 的函数，几何平均，算术平均，调和平均，反调和平局，中值，中点等-Opencv write spatial filtering, including maximum and minimum median filtering, etc., drawing on digital image processing matlab version page117 function, geometric mean,