Geometric properties of the union of maximal neighborhoods

The problem of computing area and perimeter of a digital figure presented by its discrete medial axis transform (MAT) is addressed. The figure is seen as the union of the square-shaped maximal neighborhoods centered on the local maxima of the MAT. The contribution given by each maximal neighborhood to figure area and perimeter is computed while tracing the MAT. Multiple overlaps among the maximal neighborhoods are possible. However, due to the properties of the local maxima and their associated maximal neighborhoods a single tracing of the MAT is provided to be sufficient to obtain the desired result. Thus, the procedure requires O(N) time, where N is the number of MAT pixels.<>