Robert L Krawitz (rlk@xxxxxxxxxxxx) wrote:
> Date: Thu, 6 Jan 2005 18:36:50 +0100
> From: Simon Budig <simon@xxxxxxxx>
>
> Robert L Krawitz (rlk@xxxxxxxxxxxx) wrote:
> [Exif orientation tag]
> > The obvious question is: if the rotation information isn't important,
> > why does the camera even bother with it, as opposed to doing the
> > rotation inside the camera? Why does EXIF even have a rotation tag if
> > it's useless?
>
> Good question. Actually I have wondered quite a lot about that
> already. Why the fuck doesn't a camera with an orientation sensor
> store the Jpeg in the proper orientation (quite cheap from a
> computational POV, just shuffle some coefficients around) and
> stores an *absolute* orientation tag in EXIF.
>
> What is "absolute" orientation? Orientation by its very nature has to
> be relative to *something*? I presume from what you say below that
> you mean orientation of the camera. I don't want to lose those two
> bits of information.
Point taken :-)
I meant the orientation of the camera relative to the gravitation when
the photo has been shot.
>From my glance at the Specs the Orientation tag stores
"The image orientation viewed in terms of rows of columns"
and the default value is
"The 0th row is at the visual top of the image, and the 0th column
is at the visual left-hand side."
So the Orientation-Tag is about the relation between the visual
representation of the image and the organisation of the image data - at
least this is my understanding of the specs.
It is *not* about the physical orientation of the camera.
Storing the orientation of the camera relative to the image data stored
doesn't make much sense and just happens to kind of work for exif aware
applications, because the camera abuses the ORIENTATION tag.
Bye,
Simon
--
simon@xxxxxxxx http://simon.budig.de/
