2013.12.30 12:20 "[Tiff] Situation of EXIF handling", by Jürgen_Buchmüller
I have read about the non-support for EXIF blobs in libtiff and the first steps to create an EXIF directory and to set single EXIF tags since 4.0.2.
Now it seems as if the TIFFTAG_EXIFIFD is meant to point to a TIFF directory, not to e.g. the EXIF blob inside a JPEG where the EXIF data would be stored inside one or more APP1 markers.
I searched the source and didn't see anything in tif_jpeg.c relating to EXIF, probably because JPEG in TIFF is not supposed to contain any APP1 markers anyway.
For our project my goal was to use libexif to do all the parsing and construction of EXIF blobs. It works fine with JPEG and the APP1 marker(s) so far. Do I have any chance (read: interface) to extract and insert libexif blobs from and into a TIFF myself? Would that make any sense if no specification exists how EXIF blobs should be allowed or supported?
Or is the only way to implement support for all (most) EXIF tags by adding custom TIFFFields for the EXIF tags missing in the libtiff exifFields table?