说明：  坎尼(Canny)算子,这是坎尼在1986年写的一篇论文里仔细论述的。 他给出了判断边缘提取方法性能的指标。而坎尼算子也是图像处理领域里的标准方法，也可以说是默认 的方法。
(Canny (Canny) operator, which is Cannae in 1986, carefully written exposition of a thesis. He gives the edge extraction method to determine the performance indicators. The Canny operator is also the field of image processing, the standard method, it can be said is the default method.)