Last modified: 2013-03-25 15:22:49 UTC
Was there a recent change in EXIF orientation processing on Wikimedia Commons? Sadly mediawiki rotates files if a duplicate orientation tag (with conflicting info!) is present at image files. There was a bug in Apple's iPhoto4 and it seems we have some files from it ;) input this in google: "Warning: Duplicate Orientation tag in IFD0" → Apple products. Example: one tag is 1 and another is 8. mediawiki uses the 8 instead of ignoring this obvious crap. GIMP, gthumb do not do this. They apparently only use the tag if there is only one ;) Example: https://commons.wikimedia.org/wiki/File:Pol_Roger_pupitre_4.jpg Or see my upload log of 2011-12-07 and -08 https://commons.wikimedia.org/w/index.php?title=Special%3ALog&type=upload&user=Saibo&page=&year=&month=-1&tagfilter=&hide_patrol_log=1 I have fixed some.
Question: how exactly does WM extract? And: I think it should be ignored in such cases.
Current last 500 uploads by Rotatebot: 1 such a case (0.2 %)
How do we know which one is the 'correct' one?
As an aside, this is an upstream issue, since we don't extract the exif ourselves.
(In reply to comment #3) > How do we know which one is the 'correct' one? We do not know - we can just guess or ask the user if we would be an interactive program. ;-) But it seems to be a bad idea to rotate. Do you cross the street if someone tells you "there is no car coming" and another person "there comes a car, stop!"? (In reply to comment #4) > As an aside, this is an upstream issue, since we don't extract the exif > ourselves. Which tool and which settings do we use? Is it reported? At exiftool you need to add parameter -a to get also duplicate tags. If you leave it away it does not output both. Just one - I do not know which one or if it ignores both then.
> > (In reply to comment #4) > > As an aside, this is an upstream issue, since we don't extract the exif > > ourselves. > Which tool and which settings do we use? Is it reported? > At exiftool you need to add parameter -a to get also duplicate tags. If you > leave it away it does not output both. Just one - I do not know which one or if > it ignores both then. We use PHP's exif module (which is a piece of crap for a variety of reasons, and I've contemplated just re-writing its functionality in php more than once). I think exiftool goes with the first one, and we use the last one, but that's just a guess.
(In reply to comment #6) I do now use this: exiftool -IFD0:Orientation -b -a Outputs all (-a) tags and therefore provides the full control over interpretation. ;-) So for Commons the priority is maybe not more "high major".
In case it is interesting for someone: Current rate in Rotatebot's uploads: 0.5 % (out of 840 images). Until now all images had "Quicktime" in their EXIF info.
