Comment by blacklion

Unfortunately, it doesn't help.

Almost any digital camera RAW format is TIFF inside. And you can see how much kludges good metadata library needs to read all of them: offsets from the IFD, offsets from beginning of file with or without header, offsets from fields in IFD, etc, etc, etc. You take TIFF, you change header to make your format, and then you cannot implement this TIFF properly!

Even DNG (which is tiff inside) is mangled by camera firmware authors!