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Re: [whatwg] Adding features needed for WebGL to ImageBitmap

From: Justin Novosad <junov@google.com>
Date: Thu, 18 Jul 2013 13:22:10 -0400
Message-ID: <CABpaAqS2f+av9-CnZvDjS9aNU1wU=8ziPbx8rABzZ73D7XUj3Q@mail.gmail.com>
To: Mark Callow <callow.mark@artspark.co.jp>
Cc: WHAT Working Group <whatwg@whatwg.org>, "K. Gadd" <kg@luminance.org>
On Thu, Jul 18, 2013 at 5:45 AM, Mark Callow <callow.mark@artspark.co.jp>wrote:

> On 2013/07/18 16:34, K. Gadd wrote:
> >
> > I understand the rationale behind gregg's suggestion for flipY, but
> > ultimately don't know if that one makes any sense in a HTML5 context. It
> > basically only exists because of the annoying disagreement between APIs
> > like OpenGL and other APIs like HTML5 Canvas or Direct3D, specifically
> > about which direction the Y axis goes.
> It exists because of the annoying disagreement between the orientation
> of the data in most image file formats and the default orientation for
> textures images in OpenGL. There are a some image file formats that have
> a bottom left orientation and there is one, extremely common, format,
> EXIF, that includes metadata giving the visual orientation of the image.
> The flipY item in the proposed dictionary could be handily extended to
> an enum. E.g.,
>
>   * "none" - leave orientation alone
>   * "flipY" - ignore the EXIF orientation, just flip in Y
>   * "topLeftEXIF" - identify visual orientation from EXIF data and
>     re-order data so top-down, left-to-right processing for display
>     results in correct visual orientation
>   * "bottomRightEXIF" - as above but ordered for bottom-up,
>     left-to-right processing
>
> Regards
>
>     -Mark
>

EXIF, may be a defacto standard in some image formats we use today, but I
think we should probably be more general and just refer to this as image
media meta-data.  What should the default be? I hesitate between 'topLeft'
and 'none'.
Received on Thursday, 18 July 2013 17:22:37 UTC

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