Some Parallel Thinning Algorithms for Digital Pictures
Renato Stefanelli, Azriel Rosenfeld · Journal of the ACM · 1971
If a picture contains elongated objects of different thicknesses, one can make measurements on it which are thickness-invariant by first transforming it so that each object is thinned down to a "medial line" of constant thickness.Several algorithms are described which perform such a thinning transformation when applied to the picture in parallel.It is proved that these algorithms do not change the connectivity properties of the picture.