There are many approaches to edge detection,such as thresholding gradient images,tracking edges,using wavelet transform.But these approaches generate broken,noised and improper edges.

• 灰度图阈值法、跟踪法、小波变换法是边缘检测的常用方法,这些方法所获得的边缘线出现断点,而且掺杂噪声,效果不很理想。