This program allows you to compose a number of pictures together. It is capable of extracting transparency information from images.
In this documentation I tried to give as much info as possible. Moreover, you can look though source code (or change it/recompile).
After downloading
Unzip file to whatever folder you want - and you're done: you can start a program by running a file ics.exe. Documentation is in Doc folder, main file index.html.