This was an afternoon project to determine whether crude approximations could produce reasonable results.
This is NOT complete sourcecode. It includes enough code to show the details
of how the algorithm works.
If anyone decides to make this compile separately, send a pull request.
Thanks to Brendan Duncan for contributing a pull request to fill in all of the classes and to build a simple test case. Specifically, he has contributed all of the files that do NOT begin with PvrTc
http://roartindon.blogspot.sg/2014/08/pvr-texture-compression-exploration.html