I think maybe you are assuming a square print? The original effort accepts rectangular images. I note he also has improved it quite a bit since I downloaded a copy for safekeeping a while back. Cotrell's implementation does some warning checks and offers vertical centering or top and sides equal as options too. Plus he now has input for the frame overlap. I had started to hack a copy of the old one to do that, but as usual the project of the moment didn't allow time to play with the tools!
Originally Posted by Ulrich Drolshagen