[Foundation-l] The Mediawiki 1.18 image rotation bug on Commons and on all Wikimedia projects

Mon Dec 12 19:18:40 UTC 2011

On 12 December 2011 18:18, Erik Moeller <erik at wikimedia.org> wrote:
> On Mon, Dec 12, 2011 at 7:55 AM, David Gerard <dgerard at gmail.com> wrote:
>> * How many existing uploads, used on the wikis, were previously
>> wrongly rotated and were fixed by the feature?
>> * How many existing uploads, used on the wikis, were previously
>> correctly rotated and were messed up by the feature?
>
> As far as I understand the issue, and others can jump and correct me
> if I'm getting it wrong:
>
> Technically, nothing was "messed up" by the feature. Rather, the
> software previously did not take EXIF rotation into account, and some
> images had incorrect EXIF rotation information to begin with. Those
> images are now shown in an incorrect rotation to the user, because the
> incorrect EXIF rotation info is being evaluated.

That's a big technicality. Surely the most important thing is how the
images display to users? There were right before and now they aren't.
That may not be technically messed up, but it is messed up in reality.

> It's important to understand this, because it means that those images
> have been causing problems for re-users all along. If you open those
> images with modern image editing/viewing software, they will either be
> automatically rotated, or you'll be prompted by the software whether
> to apply the rotation noted in the EXIF tag.

Indeed, it's good to get these images fixed, but surely it would have
been better to fix them rather than just break the workaround that was
stopping people noticing they were broken?

> The situation has been significantly exacerbated by a recent need to
> purge old thumbnails to free up diskspace.

How big a contributing factor has that been? As I understand it, only
thumbnails of unused images were purged. People (including me) have
been stumbling over incorrect images in articles - have they just been
unlucky and the thumbnail happened to expire at the wrong time?

> So, while the cleanup that's happening now is very frustrating (and I
> definitely agree we could have anticipated and communicated this
> better), it's a cleanup that's long overdue. (Either by stripping EXIF
> info from files altogether, or by ensuring that the rotation of the
> image matches the one in the metadata.)
>
> Is there more that we can do at the present time to help?

I think, at the moment, the most useful thing would be to automate
finding the broken images (basically, it's all images uploaded before
the feature was introduced that have a non-zero EXIF rotation).