该算法是通过统计图像某一边缘法向方向的灰度变化情况来进行评价。即灰度变化越剧烈， 边缘越清晰， 图像也越清晰。-The algorithm is an edge of the image through the statistical method to change the direction of the gray scale to be evaluated. The more intense the gray change, the more clear the edge of the image are more clear.