I really don't want to carry all of these description strings around in the gallery app where they would sit unused.  I don't even like the type and IFD properties being strings instead of integers.  tagHex just seems silly since that can be derived from the tag number.

At a minimum, please convert the descriptions to comments.

But consider refactoring so you have a low-level library that does everything with symbolic constants and integers.  Then create an independent library that can take the low level output of the first library and stringify it to make it human readable.  Seems like localization would be  a hard problem though.