Skeletonizing the distance transform on the hexagonal grid

An efficient skeletonizing algorithm is presented for the hexagonal grid. The skeleton has unit width, except at crossings and in regions of the shape having even width. Otherwise the skeleton has all the properties generally required for correct skeletons. It includes all local maxima, so complete recovery of the original shape is obtained by using the reverse distance transformation. The algorithm uses only local operations. Thus it can be performed both on sequential and parallel computers. In the sequential case described only three passes through the image are necessary, two to compute the distance transform and one for the identification of skeletal pixels