By means of this relation, any binary point (x,y) in image space X-Y is mapped into a sinusoidal in the accumulator space ρ-θ , which is discretized in cells of coordinates (ρ,θ) . The main feature of the HT is that the N sinusoidals corresponding to a set of N collinear points (xi,yi) meet at a point (ρo,θo) in accumulator space, the values of ρo and θo characterizing the original straight line in the image. Every sinusoidal passing by (ρ,θ) contributes with 1 to a counting stored in that location. The counting stored in every cell of the accumulator corresponds to the number of points that are contained in a straight line characterized by (ρ,θ) in eq. (1).