Comment 4 for bug 644168

> 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.