I'm working on a project involving puzzles made out of user-supplied images. I have been very hard-pressed to find a library that will serve my purposes. I would like to write the program in either Python or C++. I have been considering using Qt (or PyQt) to do it, so if you know of a library that will work with Qt it would be nice, though at this point anything would be nice.
You can't expect to find a library for any specific task. In this case, you need image-processing library, which is able to:

draw image region with transparent background. You have piece configuration, use it as a mask to cut out edges.
save drawn image to some format.

Qt graphics is totally able to do all that.
Anyone know of a C++ or Python library that will divide an image into pieces of arbitrary shape?