Ah, now I understand why the files must be named in accordance with md5sum. My tool avoids that problem by not modifying the file at all, using TMSU to tag it instead. This has corresponding tradeoffs, of course (if your file manager isn't TMSU aware, renaming or duplicating the file after you've tagged it is not a good idea. On the other hand, you can tag any file type, not just PNGs or JPGs.)

However, previously I had some files which included both a normal name and md5sum string, separated by a comma. That is an option you could consider supporting.