Canny edge detection is a technique to extract useful structural information from different vision objects and dramatically reduce the amount of data to be processed. It has been widely applied in various computer vision systems
*Detection of edge with low error rate, which means that the detection should accurately catch as many edges shown in the image as possible
*The edge point detected from the operator should accurately localize on the center of the edge.
*A given edge in the image should only be marked once, and where possible, image noise should not create false edges.