A modification of Deriche´s approach to edge detection

Canny (1983) presented criteria for measuring the quality of edge detectors and derived an optimal FIR-filter for step edges by optimizing them. Four years later Deriche proposed an approach to edge detection based on Canny´s design utilizing IIR-filters which can be implemented very efficiently and recursively. Using the Deriche-filter leads to a distortion of the amplitudes of the edges depending on their direction. In this paper, it is shown that these distortions are systematic errors which can be eliminated by a simple modification of the edge detection procedure. Because of its obvious `kinship´ to the Deriche-filter the Shen-filter has been included in the investigations