Good old UNIX
They say that one never forgets how to walk - with my 12year outdated unix experiences it like the same. But I'm very happy with some project like "DarwinPorts" that enabled me to get the netPNM libraries running on my computer.
So, now I started playing with all those routines there are now placed on my computer; over 300 new commands to work with graphics. My first attempt was not bad at all, only need to figure out how to work with the transparencies of the puzzle pieces, but I'll manage.
The puzzle is going to become more realistic too, the pieces will be 'rotatable' in steps of 15 degrees. uhm yes.... 24 variants of every single piece, 4800 pieces already - some batch processing might be nescecary. But in day life, one does not know how a piece needs to be place, rotate it a quarter turn, another? Unless there is a clear pattern one can see how it needs to be place. Four rectangular versions would be enough, but I think I will love the animation effect and need the intermediate images too.
Back too playing around with the unix scripts for manipulating the files. That transparency will work (I have read it somewhere) and positioning at the right place will be worked on too, also re-slicing the file again is something to do, I can't have 1MByte files sizes to transmit on the web; small chunks and some kind of inteligent caching or some kind of streaming will have to solve the problem.