Cellular automata is a new fast and effect theory tool for realizing image processing algorithm,whose emphasis is on how to determine its state transition function.For infrared image edge detection,three of state transition functions are studied and realized,which are max_min method,threshold method,and morphological gradient method.Compared with classical edge detection methods,the experimental results show that the new methods based on cellular automata not only have good detection effects,but also can be realized on real-time.