Canny 的目标是找到一个最优的边缘检测算法，最优边缘检测的含义是：

好的检测- 算法能够尽可能多地标识出图像中的实际边缘。

好的定位- 标识出的边缘要尽可能与实际图像中的实际边缘尽可能接近。

最小响应- 图像中的边缘只能标识一次，并且可能存在的图像噪声不应标识为边缘。-Canny goal is to find an optimal edge detection algorithm, the optimal edge detection means:

Good test- algorithm can identify as many as possible of the actual edge image.

Good Location- identifies the edge as much as possible with the actual edge of the actual image as close as possible.

Minimum response- edges in the image can only be identified once, and there may be noise in the image should not be identified as edges.