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incorrect duplicate EXIF IFD0:Orientation tag handling ("Warning: Duplicate Orientation tag in IFD0")
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Description

Author: saibotrash

Description:
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.


Version: 1.18.x
Severity: major

Details

Reference
bz32868
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Event Timeline

bzimport raised the priority of this task from to Medium.Nov 22 2014, 12:05 AM
bzimport set Reference to bz32868.
bzimport added a subscriber: Unknown Object (MLST).

saibotrash wrote:

Question: how exactly does WM extract? And: I think it should be ignored in such cases.

saibotrash wrote:

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.

saibotrash wrote:

(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.

saibotrash wrote:

(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".

saibotrash wrote:

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.

Aklapper changed the subtype of this task from "Task" to "Bug Report".Feb 6 2022, 7:18 PM
Aklapper removed a subscriber: wikibugs-l-list.
TheDJ subscribed.

No major further complaints about this.
It was aggravated by an apple bug which was long since fixed and there was no reliable way to determine what the right value was supposed to be.