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Re: Image use cases that WCAG doesn't address

From: Loretta Guarino Reid <lorettaguarino@google.com>
Date: Thu, 23 Oct 2008 18:41:30 -0700
Message-ID: <824e742c0810231841j44cdfb1dv7bb17368f3b2591b@mail.gmail.com>
To: "Henri Sivonen" <hsivonen@iki.fi>
Cc: public-comments-wcag20@w3.org

On Wed, Aug 20, 2008 at 2:10 AM, Henri Sivonen <hsivonen@iki.fi> wrote:
> This comment is about Guideline 1.1 Text Alternatives, and this comment is
> about the substance of the guideline.
> The HTML5 draft[1] gives advice and examples for including text alternatives
> for a variety of image uses cases. As far as I can tell, the following use
> cases aren't addressed by WCAG 2.0:
>  * A diagram illustrates what is already said textually. (HTML5 says alt=""
> for this case.)
>  * A user-uploaded image whose content is unknown to the programmer of the
> HTML generator that frames the image for Web display and the user hasn't
> supplied a text alternative. (HTML5 says to put the description of what kind
> of image the image is in curly braces in the alt attribute. E.g. a photo
> sharing site would use alt="{photo}".)
> Proposed change:
> I propose aligning with the HTML5 draft by saying that an image be marked as
> omissible from non-visual rendering if it illustrates what the surrounding
> prose already says.
> I propose aligning with the HTML5 draft by saying that if the generator of
> markup does not have a text alternative available, it should use the
> natural-language expression describing the kind of content (to the precision
> known to the generator) as the text alternative and use a mechanism provided
> by the host format for marking the text as not really being a text
> alternative but an indication of what kind of non-text content is in
> question.
> [1] http://www.w3.org/html/wg/html5/
> --
> Henri Sivonen
> hsivonen@iki.fi
> http://hsivonen.iki.fi/

Response from the Working Group
We try to make our guidelines match technical standards to the extent

We have looked at the HTML 5 standard and we note that although many
of the examples match the WCAG 2.0 guidelines - some do not, including
the ones you mentioned. (although the second example you mention seems
to have been removed from the September editors draft)

We are adding one sufficient technique to make it clear that some of
the examples in HTML 5 do conform with WCAG.  The new technique is:

G196: Using a text alternative on one item within a group of images
that describes all items in the group

As for the other one you cite above,  we think that WCAG currently
draws the line in the right place and changing the standard would
create problems for accessibility.

Loretta Guarino Reid, WCAG WG Co-Chair
Gregg Vanderheiden, WCAG WG Co-Chair
Michael Cooper, WCAG WG Staff Contact

On behalf of the WCAG Working Group
Received on Friday, 24 October 2008 01:42:08 UTC

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