Corner feature is widely used in pattern recognition for it is invariant to scale

shift and rotation. This paper introduces three algorithms to extract corner feature

named splitting merging algorithm

the extended Hough transform algorithm and the extended corner algorithm. Among them the splitting merging algorithm is the easiest one to implement but is the most sensitive to noise. The extended Hough algorithm is much strong to noise and the last algorithm is much more suitable to describe the characteristics of practical contours. Result of computer simulation for recognizing four occluded objects by using these algorithms is given.