2009.10.28 15:18 "[Tiff] extending tags in "a"ppend mode?", by Juergen Buchmueller

2009.12.06 15:02 "Re: [Tiff] Adding tags to a broken(?) TIFF", by Juergen Buchmueller

FYI: I solved the problem by creating a new TIFF on the fly.

It seems that libtiff doesn't handle extending a directory without overwriting data at all. If a directory size increases, libtiff would have to relocate the entire directory entry with all existing tags to e.g. the end of the file. It doesn't do that now, but writes the new tag to the file right after the end of the current directory, thereby destroying whatever is there.

That's just my observation without looking into libtiff's source.

Juergen