canny算子可以提取到很好的物体的边缘，效果要比拉普拉斯算子及罗伯特算子的效果都要好，代码中得到的效果很好，并且将图片进行了一倍和两倍的缩小-canny operator can extract the edge of the great objects, the effect than the Laplace operator and operator Robert effect to be good, with good results obtained in the code, and