Openings can introduce zero crossings in boundary curvature
P. F. M. Nacken · IEEE Transactions on Pattern Analysis and Machine Intelligence · 1994
Chen and Yan (1989) presented a result on zero crossings of boundary curvature under morphological openings. In this correspondence, it is shown, by means of a counter example, that this result is not correct. An analysis of the counter example shows where Chen and Yan go wrong and determines a class of images for which their theorem holds.>