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Re: feedback requested on WAI CG Consensus Resolutions on Text alternatives in HTML 5 document

From: Steven Faulkner <faulkner.steve@gmail.com>
Date: Mon, 17 Aug 2009 11:38:24 +0100
Message-ID: <55687cf80908170338w4931a60bo7f74fe1c9a83ed97@mail.gmail.com>
To: Maciej Stachowiak <mjs@apple.com>
Cc: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>, Ian Hickson <ian@hixie.ch>, HTMLWG WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
hi benjamin,
<p>As you can see from the chart below, sales increased in 2008:</p>
<img alt="" src="chart.png">

from my understaning this does not conform to WCAG 2.0.
here is an example from wcag 2.0 of what is required.

*"A data chart*

A bar chart compares how many widgets were sold in June, July, and August.
The short label says, "Figure one - Sales in June, July and August." The
longer description identifies the type of chart, provides a high-level
summary of the data, trends and implications comparable to those available
from the chart. Where possible and practical, the actual data is provided in
a table. "

http://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv-all.html#text-equiv-all-examples-head
if an image contains complex information it should have some form of text
alternative and should  be mapped to the accessibility API.

some possible examples of achieving this
<figure><p>As you can see from the chart below, sales increased in 2008:</p>
<img  src="chart.png">
<legend><a href="chart.html">full description of chart</a></legend>
</figure>

<p id="chart1">As you can see from the chart below, sales increased in
2008:</p>
<img src="chart.png" aria-labelledby="chart1" aria-describedby="chart2">
<a href="chart.html" id="chart2">full description of chart</a>

regards
stevef

2009/8/17 Maciej Stachowiak <mjs@apple.com>

>
> On Aug 17, 2009, at 2:00 AM, Benjamin Hawkes-Lewis wrote:
>
> On 17/08/2009 09:42, Maciej Stachowiak wrote:
>>
>>> Would it be appropriate, in light of this, to add a user agent
>>> requirement that an img with empty alt should not be mapped to
>>> accessibility APIs at all?
>>>
>>
>> Given the variety of authoring practice around "alt", I don't think that
>> would be safe.
>>
>> In situations like:
>>
>> <a href="#"><img src="delete.png" alt=""></a>
>>
>> It's useful to AT for the "img" to be exposed and to be able to access
>> "src" attributes for the purpose of providing a substitute for proper
>> alternative text.
>>
>
> If that's so, then wouldn't it be better for authors to use alt="" instead
> of role="presentation", so that AT can decide whether it needs to expose the
> image anyway? In particular, if your example was marked up like this:
>
> <a href="#"><img src="delete.png" role="presentation"></a>
>
> Then isn't it equally necessary and appropriate for AT to expose that
> image?
>
> It seems like, based on this example, images should always be exposed to
> accessibility APIs, and AT should make the call on whether it needs to
> override the author-provided semantics.
>
> http://www.w3.org/TR/WAI-USERAGENT/guidelines.html#tech-missing-alt
>>
>> More tendentiously, perhaps, in situations like:
>>
>> <p>As you can see from the chart below, sales increased in 2008:</p>
>> <img alt="" src="chart.png">
>>
>> Even if users can't consume the chart themselves, it's useful to users to
>> be able to download or hotlink that referenced chart in a collaborative
>> environment (e.g. a corporate wiki).
>>
>> By contrast:
>>
>> <img alt="" src="bullet.png">
>>
>> really is purely decorative; in a collaborative environment that seems
>> likely to be generated by authoring software.
>>
>
> And likewise for these examples - it seems like AT should be left free to
> apply heuristics.
>
> Regards,
> Maciej
>
>
>


-- 
with regards

Steve Faulkner
Technical Director - TPG Europe
Director - Web Accessibility Tools Consortium

www.paciellogroup.com | www.wat-c.org
Web Accessibility Toolbar -
http://www.paciellogroup.com/resources/wat-ie-about.html
Received on Monday, 17 August 2009 10:39:07 GMT

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