An algorithm to extract convex hull on &thetas;-ρ Hough transform space

It is theoretically shown that the envelope of the distribution of the Hough curves in θ-ρ parameter space corresponds to the convex hull of the pattern in x-y space. Using on this property of the Hough transform, the procedures defined on the Hough transform are constructed so as extract the envelope, calculate the x and y coordinates of the convex hull elements, and decide their connection order