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Re: HTML Action Item 54 - ...draft text for HTML 5 spec to require producers/authors to include @alt on img elements.

From: Steven Faulkner <faulkner.steve@gmail.com>
Date: Mon, 12 May 2008 13:57:24 +0100
Message-ID: <55687cf80805120557s121ce793m4d84bd82af421f54@mail.gmail.com>
To: "Maciej Stachowiak" <mjs@apple.com>
Cc: "public-html@w3.org" <public-html@w3.org>, "W3C WAI-XTECH" <wai-xtech@w3.org>, wai-liaison@w3.org, "Dan Connolly" <connolly@w3.org>, "Chris Wilson" <Chris.Wilson@microsoft.com>, "Michael(tm) Smith" <mike@w3.org>

Hi Maciej,

>This proposal does not cover the use case
> where HTML generated by a tool does not have a textual alternative
> available.

The current draft of item54 does not provide explicit coverage, as stated:

'Advice has been sought, is needed, and is pending from PFWG regarding
the separate issue of what an authoring or publishing tool should
insert, in a case where no alt has been provided by the author, but
the image is known to be "critical content".'

source: http://www.paciellogroup.com/blog/misc/uc/

But, the proposal does implicitly cover the use case (the content will be
invalid, because the author is either using a broken authoring tool,
or doesn't care about the structure of the data).



> It also requires redundant text in many cases where the current spec would
> call for empty alt.

The current spec conflicts with WCGA 2.0 (candidate recommendation)
advice on such images.

As stated in the proposal;
"The aim of this draft is therefore to comply with WCAG 2.0, Guideline
1.1. Text Alternatives:"

source: http://www.paciellogroup.com/blog/misc/uc/

> Is there any reason to believe that redundant text description of an image
> that recapitulates the text is helpful, rather than harmful, to users who
> use textual alternatives?


potential benficiaries of this information include, blind users,
visually impaired users, cognitively impaired users and user with
intellectual disabilities. each of the user groups have different
needs and AT that they use will consume and present the information in
a variety of ways, users are also provided with a wide variety of
options on how to navigate and access content. So your simplistic
notion of redundancy does not hold up.

examples:
A screen reader user may initially hear the short summary of the image
content, then access then access the longer description via a key
stroke.

The screen magnifier/reader user who can see the image, but not
understand its contents due to it being to blurred, will have the alt
text announced, to give them some idea of the image content.

The cognitively impaired user accessing the page using a talking
browser, likewise will have the benefit of a short image label,
although they may not be able to understand the content of the image
from its visual rendering.

for all of these users the presence of the short alt text provides an
alternative labelling mechanism that can be presented to the user via
their AT.

For the magnifier user, the short text alternative may or may not be
provided visually. The association between the aria-describedby text
and image could be rendered visually in a number of of ways.

 Different AT's currently provide different mechanisms to navigate and
access content. For example screen readers such as JAWS provides
methods to navigate a page via graphics (using the G key), in this
case, not providing the alt text means that the image would be
skipped.

> Is there reason to believe that screen reader users like to hear things two
> or three times? I have not done any studies but this is surprising to my
> intuition. I would have concluded that using alt="" to present the screen
> reader user (or other users of aural or text-only media) with the
> information only once is best. It may be that this surprising conclusion is
> correct but I would like to hear some justification.


As stated previously

"The aim of this draft is therefore to comply with WCAG 2.0, Guideline
1.1. Text Alternatives:"

The advice in WCAG 2.0 has been developed over a long period of public
consultation. If you feel that your view of what constitutes best
advice on how to provide appropriate text alternatives is superior to
WCAG,  I urge you to correspond with the WAI WCAG working group. I am
sure that they would be more than happy to explain how they arrived at
the advice provided in WCAG 2.0.


regards
stevef


On 12/05/2008, Maciej Stachowiak <mjs@apple.com> wrote:
>
>
> Hi Steve,
>
> On May 8, 2008, at 8:28 AM, Steven Faulkner wrote:
>
> Dear HTML WG members,
>
> The first draft of our rewrite of major sections of 3.12.2 "The img
> element" in the HTML5 draft is now available:
>
> http://www.paciellogroup.com/blog/misc/uc/
>
> Thanks for writing up a proposal. This proposal does not cover the use case
> where HTML generated by a tool does not have a textual alternative
> available. Examples include:
>
> - Dragging a photo into a WYSIWYG mail program's composer (Mail programs do
> not normally prompt for a description and doing so would be confusing to
> users)
> - Bulk upload of photographs to a photo sharing site, where the photographer
> is unwilling to put in the effort to individually describe each one
> - A script that scrapes images from other sources that lack text
> alternatives, and generate html
>
> These would all be covered by "Images of Pictures" but the required
> description is not available. Thus, the proposal does not cover all the use
> cases handled by the current spec language.
>
>
>
> It also requires redundant text in many cases where the current spec would
> call for empty alt. For example:
> <p id="piedescription">According to a study covering several billion
pages,
> about 62% of documents on the Web in 2007 triggered the Quirks rendering
> mode of
Web browsers, about 30% triggered the Almost Standards mode, and
> about 9% triggered the
Standards mode.</p>
> <p><img src="rendering-mode-pie-chart.png" alt="The
> majority of
documents triggered quirksmode."
> aria-describedby="piedescription"></p>
>
>
> Is there any reason to believe that redundant text description of an image
> that recapitulates the text is helpful, rather than harmful, to users who
> use textual alternatives? After all, "The majority of documents triggered
> quirksmode" is just a restatement of "62% of documents on the Web in 2007
> triggered the Quirks rendering mode of Web browsers". Furthermore,
> aria-describedby would link the image to a long description, thus possibly
> leading the screen reader user to hear the same information yet a third
> time.
>
> Is there reason to believe that screen reader users like to hear things two
> or three times? I have not done any studies but this is surprising to my
> intuition. I would have concluded that using alt="" to present the screen
> reader user (or other users of aural or text-only media) with the
> information only once is best. It may be that this surprising conclusion is
> correct but I would like to hear some justification.
>
>
> 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, 12 May 2008 12:59:09 GMT

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