[Gimp-developer] 2.6 roadmap: metadata and jpeg plug-inenhancements

[William Skaggs]

From: Karl Günter Wünsch <kgw at mineralien-verkauf.de>

>EXIF in an edited image has little resemblance with the original anyway, so I 
>would suggest stripping that except for the IPTC tags. I would also be happy 
>if the IPTC tags were settable in the GIMP, instead of having to resort to 
>other programs.

No!  EXIF in an edited image is still highly relevant, but it should not merely
be copied from the original, as GIMP used to do.  The EXIF specification gives 
precise instructions about how the EXIF data should be altered when an image is 
edited and saved, and to the best of my knowledge -- I just looked at the code 
again -- GIMP now follows the specification pretty closely, and has done so for 
almost three years.  The file "exif-handling.txt" in devel-docs summarizes
my understanding of what the specification requires us to do.  You can look at 
the function jpeg_setup_exif_for_save() in plug-ins/jpeg/jpeg-exif.c to see what 
GIMP currently does to the EXIF.  As an example,  the specification says that the 
orientation should *always* be set to "top-left"  when an image is saved after
editing, regardless of what it was when loaded.  People may argue about whether 
that is always the best thing to do, but it is what the specification requires, 
so it is what GIMP does.  To the best of my knowledge, it does this regardless 
of what decision the user makes about rotating when loading.

  -- Bill
 

 
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