Ambiguity distance: an edge evaluation measure using fuzziness of edges

Most edge detection methods have parameters (threshold values or standard deviation of Gaussian operator for smoothing) to be set, and these parameters make much influence on the outputs of the detectors. In this paper we propose an objective parameter evaluation measure. We evaluate parameters based on the edge ambiguity measures of existence, location and formation. The existence and location ambiguity measures are derived from comparing fuzzy memberships of edgeness with detected edges, and the formation ambiguity measure assesses the connectedness and the total number of edge point in an edge image with respect to the image size. The parameters which produce the least ambiguous edges of a detection method for an image are selected as significant ones. No iterative visual interaction or prior knowledge of edges are needed for these evaluation measures, The effectiveness of the measures is demonstrated by applying the ambiguity measures to synthetic and real images. (C) 2002 Elsevier Science B.V. All rights reserved.