I. Introduction
Edge is the place which has more or less mutations in image gray level or structure information, is the end of one area and another area to start [1]. Not only edge can convey a large number of information of the image edge and draw the basic contour of the object, so edge detection is very important to computer vision system, and has very important role in image segmentation, pattern recognition, computer vision and so on. Edge detection is an important part in the image processing, and is first-term work of all based on boundary segmentation method, such as 3-D reconstruction and image segmentation and so on. The field of image processing active research problem is edge detection, especially color image edge detection is a problem of deserve to research.