Edge detection and characterization of digitized images

We present a method for determining which of a large set of pixels are inside or on the boundary of a polygon. The method works much quicker than the standard method used for points in general and also provides an ordering of the boundary pixels. Once the edge pixels have been chosen and ordered, we move on to the characterization of the edge. We present a method for characterizing the edge slope of digitized images, which is-to a desired tolerance-invariant to rotation. We demonstrate that this characterization is good enough for subsequent use in edge identification and matching algorithms. This allows us to continue, e.g., to juxtaposing corresponding pieces of a jigsaw puzzle, or "sewing" back together, ripped pieces of material, paper or glass.