registry team mailing list archive

[Jim Nelson <jim@xxxxxxxxx>]

> 2) When GNOME takes a screenshot, it does not add any EXIF data at all. 
...
> Should I fill a bug for gnome-screenshot ?

EXIF is not required for image files.  If it's not present the
orientation is assumed to be Top Left, which means no rotation.  So, no,
I don't think gnome-screenshot is at fault here.

However, now that I look a little closer I do see one potential issue
... we're using the EXIF Orientation field to rotate PNG files.  This is
important with lossy formats, like JPEG, but not as much a win with
lossless formats, like PNG.  More significantly, EXIF is closely
associated with JPEG and digital photography, but not nearly as
widespread in the computer graphics (i.e. PNG) world.  The problem with
GIMP and EoG may simply be that they're not reading the EXIF data from
the PNG.  (In fact, libexif doesn't even support reading EXIF from PNG,
one reason we switched to Exiv2).

We should be more cognizant of this in Shotwell.  When we export a non-
JPEG file, we shouldn't rely on the Orientation field to rotate it.
I've ticketed this: http://trac.yorba.org/ticket/2585

If those other apps are not respecting the Orientation field in a JPEG
file, I do consider that to be a problem.  Most modern cameras generate
the field rather than rotate the image prior to encoding.

** Bug watch added: trac.yorba.org/ #2585
   http://trac.yorba.org/ticket/2585

-- 
Rotation in Shotwell is incompatible with some other applications
https://bugs.launchpad.net/bugs/644168
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Administrators, which is the registrant for Shotwell.