2005.12.13 18:13 "Re: [Tiff] Writing EXIF data?", by Paul J. Lucas
Since EXIF data is an IFD, and some tag values may be longer the 4 bytes, there's offsets there.
Thus, how to build that 'blob' depends on where you're going to write it.
No it doesnt since all the offsets inside the EXIF IFD are relative to its start. It's the same as for a JPEG file. EXIF data is in a JPEG's APP1 segment. The APP1 segment is self-contained. All offsets are relative to its beginning.
I hope you were aware.