As I reported in this thread: Anyone know of a MP3Tag-like program for managing metadata of pictures? - Off-Topic - Mp3tag Community
which I now realize is a duplicate of this thread (I tried searching, really, I did!),
I find that IMatch is unrivaled at this and is developed by someone who I believe is as commited to product development as Florian. An excellent program! I am just scratching the surface on what it can do.
Edit: I can't recommend the program any longer, see details below.
After trying to learn this program for a year and dealing with issues, I cannot recommend iMatch. Maybe if you wanted to do some simple tagging but the program has many features that will get you into trouble with no warning that you may face some issues. Worst still, the developer will abandon you, if the problem is too hard to fix. He literally does not believe that if an issue exists with his program, he should resolve it. As such, how many bugs may exist in this program? Who knows but I am really disappointed in his lack of commitment to his users. Exactly the opposite can be found with Florian, but he is very rare.
Still I must agree with Crissov, that I would think that MP3Tag could be extended to support image files. I do not believe that IMatch can do the filename>Tag and other functions MP3Tag can perfom, but again, I am just scratching the surface.