Abstract: In robot path planning,the robot digital roadmap recognition is very important.The image preprocessing can affect the recognition result.Image enhancement is always used in image preprocessing to provide better input for the following automated image processing,and fuzzy image enhancement is one of an effective approach that is used widely in image preprocessing. Through the research of the Pal fuzzy enhancement algorithm,it is found that there are two main bugs of the algorithm. The first one is the definition of the membership function,and the second is the selection of the transition point.In this paper,a novel improved algorithm is proposed by analyzing the deficiencies of Pal algorithm.First,the OTSU operator is used to automatically select the best threshold value,and the disadvantage of the transition point image information loss is solved.Then,the core membership function of the fuzzy enhancement algorithm is modified.Finally,the new algorithm is applied to process digital roadmap for PioneerⅢrobot.The experimental results indicate that the proposed image enhancement method can achieve better performance,and has higher processing speed than now-available fuzzy image enhancement algorithms.And it also possesses the property of high practicability and generality.