“…These operators are only suitable for detecting limited types of edges and are highly susceptible to noise often resulting in fragmented edges. More recent edge detection techniques are based on optimal filtering (Canny, 1987;Dickey and Shanmugam, 1977;Lee and Wasilkowski, 1991;Sarkar and Boyer, 1990;Shen and Castan, 1992), random field models (Cressie, 1991;Hansen and Elliot, 1982;Huang and Tseng, 1988), surface fitting (Haralick, 1984;Nalwa and Binford, 1986;Sinha and Schunk, 1992), heuristic state-space search (Ashkar and Modestino, 1978;Martelli, 1976;Montanari, 1971), anisotropic diffusion (Perona and Malik, 1990;Saint-Marc et al, 1991), residual analysis and global cost minimization using hill-climbing search (Tan et al, 1989), simulated annealing (Tan et al, 1991), mean field annealing (Acton and Bovik, 1992) and the genetic algorithm (Bhandarkar et al, 1994).…”