Concavity Point Detection by Iterative Arrays

Points of concavity constitute an important feature of every digital picture. A 1-1 correspondence exists between them and any significant negative inflection of the digitized contour. Each point of concavity may be seen as a point marking the superposition region of two convex contours. A sufficient condition is given in order that a simple arc of the contour be concave and a parallel process is shown by means of which one point of concavity is detected in correspondence to every concave arc. An iterative array of the type of CLIP 3 has been used to implement the process and a description of the behavior of the machine is given. A detailed program is included.