Hydrophobic measurement is a major way to evaluate the performance of an insulator and ensure its safety.Based on fuzzy mathematics theory

an edge-detecting algorithm is presented in this paper by combining fuzzy membership functions of GAP and relative entropy coefficient classifier.The algorithm effectively deals with the problems of completing the water drop’s missing boundary on the opposite side of the drop shadow.Experimental results indicate that

compared with the conventional edge operator

the proposed algorithm is efficient to extract edge information of droplets（or watermarks） and obtain better performance.