Improving the speed of convex hull calculations

In certain applications of image analysis (e.g. automatic visual inspection) it is possible to obtain silhouettes of isolated objects. In such situations, it is possible to use the algorithm and hardware discussed in this article. A hardware mechanism is described that is able to select points from a binary image corresponding to local changes in the direction of a black/white edge. This allows the subsequent, software-based, computational work to be reduced by a substantial amount; in the examples cited, the average savings exceeded 80%. The technique can tolerate holes in the silhouette.