中文说明：应用log算法进行图像的边缘检测，log算法是一种基于灰度值的二阶导数来进行边缘检测的，通过检测零点来进行边缘检测
English Description：
Log algorithm is used to detect the edge of image. Log algorithm is based on the second derivative of gray value to detect the edge. It detects the edge by detecting the zero point