W3C home > Mailing lists > Public > www-style@w3.org > December 2011

[css3-images] honoring EXIF orientation from images

From: L. David Baron <dbaron@dbaron.org>
Date: Wed, 30 Nov 2011 16:09:17 -0800
To: www-style@w3.org
Message-ID: <20111201000917.GA28848@pickering.dbaron.org>
One thing we've discussed at least once in the past, and I'm
surprised not to see in css3-images (other than in a note), is a way
for Web content to opt in to browsers honoring the EXIF orientation
on images.

There's a compatibility problem with honoring EXIF orientation by
default.  However, providing authors a way to opt in to honoring it
would allow authors to avoid the problem of incompatibility between
the other image processing software they use and the Web platform.

It seems that an obvious place to put this functionality would be in
the image-orientation, perhaps as 'image-orientation: from-image'.

However, this would also require extending image-orientation to
support flipping, since there are 8 EXIF orientations.  It's not
immediately clear to me how to do this given the current syntax
(expressing image-orientation as an <angle>).  However, I tend to
think that <angle> may be the wrong syntax for image-orientation:
transformations other than the 8 EXIF orientations seem like the
role of 2D transforms and not a sensible future extensibilility
direction for the image-orientation property.

I would suggest reworking image-orientation to support the 8 EXIF
orientations with a non-<angle> syntax and then adding a
'from-image' keyword.  (I think the <angle> syntax is also bad
because it suggests that angles that aren't multiples of 90deg are
meaningful.)

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂
Received on Thursday, 1 December 2011 00:09:44 GMT

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