2005.12.12 22:19 "[Tiff] Writing EXIF data?", by Paul J. Lucas

2005.12.13 21:24 "Re: [Tiff] Writing EXIF data?", by

I stand corrected. I took a look at my code for parsing the EXIF IFD.

The offsets saved in the tiff file are offsets from the start of the TIFF file. However I rewrite the entire exif IFD in memory with relative offsets (saved as a blob) so as to be consistent with the blob that is contained in JPEG files. This allows using the same lower level libs for parsing the exif data.

Lou Sakey
KNET 27-67676

"Joris" <joris.at.lebbeke@skynet.be>
Sent by: tiff-bounces@lists.maptools.org
12/13/2005 03:27 PM

        To:     <lou.sakey@kodak.com>
        cc:     tiff@lists.maptools.org

        Subject:        Re: [Tiff] Writing EXIF data?

It has been my experience that all the offsets inside the EXIF IFD are infact relative to its start.

An EXIF IFD is an IFD. Take a look at the TIFF specification, part I, section 2, and/or the TIFF FAQ, question 3, http://www.awaresystems.be/imaging/tiff/faq.html#q3.

TIFF never contains offsets other then offsets from the start of the TIFF file. That's one of the most primary rules in TIFF. EXIF does not break this. MakerNote does break some of these rules, and that's one of the reasons normal TIFF handling does get into trouble with MakerNote data.