ON USING DIRECTIONAL INFORMATION FOR PARAMETER SPACE DECOMPOSITION INELLIPSE DETECTION

In this paper we use the parameteric polar representation to extend th e application of edge directional information from circle to ellipse e xtraction. As a result we obtain a mapping which decomposes the parame ter space required for ellipse extraction into two independent sub-spa ces and one final histogram accumulator. The mapping includes the tang ent of the angle of the first and second directional derivatives. Thes e tangents are computed by considering edge direction at two border po ints. We show that the use of gradient information for parameter space decomposition avoids the intensive point labelling imposed by geometr ic constraints used by other approaches.