Texture Remix (my image manipulation tool) - v1.2.0

[Peardian]

So, from the OP, I'm assuming this means that any kind of normal map can be produced by this tool, as long as it uses similar channel mapping. The question therein becomes "what kinds of channel maps do Sonic Generations use, and how do I convert them to something OpenGL-friendly, since I don't understand how either parses normal maps?"

Not quite. You can only use it to convert normal maps from things that are already normal maps with different channel mapping. I included a tutorial image in the zip that gives the basics of Normal maps and how to use the program. I haven't worked with OpenGL personally, but I'm sure that it uses the common type of normal maps.