W3C home > Mailing lists > Public > public-html@w3.org > April 2008

Re: New issue: IMG section of HTML5 draft contradicts WCAG 1 & WCAG 2 (draft)

From: Benoit Piette <benoit.piette@gmail.com>
Date: Fri, 11 Apr 2008 09:29:30 -0400
Message-ID: <ecc676290804110629h675f0f7lbb95cea4f0708de1@mail.gmail.com>
To: public-html@w3.org, wai-xtech@w3.org
>From what I understand there is 5 different cases :
1) I have a suitable alt text available
2) I forgot to put a suitable alt text
3) There might be a suitable alt text, but it is not available to the system
generating the page
4) The image is presentational in nature and it must not have alt text
(alt="")
5) I have an alt text and it is bad

2) is clearly not validating and not conforming
1) & 4) are what we want ideally and are considered best practice
3) Cannot be made accessible, but still should be validating and conforming
in cases when the system clearly cannot make the page accessible in any way
5) validates but does is not conforming

We can decide politically speaking, that not accessible pages are not
conforming. In this case, alt is required for validation and it must have
suitable replacement text. 3) will never output correct html and we have to
accept that.
Systems MUST (in RFC 2119 sense) generate accessible pages. 3) is simply not
a valid case QED.

If we use SHOULD, which is what I think we are trying to achieve here, then
3) is a correct case and must be allowed but is not recommended.

Personally, I think something along the lines of

<img src="toto.png" noalt >

in pages that have a meta tag saying that the content is generated and all
semantic information is not necessarily available to user agents would not
be ambiguous in any way.

This is correct if in HTML 5, human generated web pages MUST be accessible,
but software generated web pages SHOULD be accessible. This in itself can be
debated, but if it is not clear, then any solution we come up with will not
have a solid base to witch to stand on.

Benoit Piette
http://w3qc.org
http://benoitpiette.com




2008/4/11, Steven Faulkner <faulkner.steve@gmail.com>:
>
>
> Two images without explicitly associated text alternatives.
> 1 is an image is decorative that the author has accidently left off
> the alt, the other is "critical content" that the author could not
> provide an alt for whatever reason
> 1 can be safely ignored, the other should be brought to the attention
> of the user.
>
> <img src="abc.jpg">
>
> <img src="xyz.jpg">
>
> How is Assistive Technology  supposed to reliably determine this?
> Given that these two images could be the same, but their meaning
> differ widely depending on the intent of the author in regards to
> their use.
>
> regards
> steve
>
> On 11/04/2008, Laurens Holst <lholst@students.cs.uu.nl> wrote:
> > Henri Sivonen schreef:
>
> >
> > >
> > > On Apr 11, 2008, at 11:23, Steven Faulkner wrote:
> > >
> > > > 5.  Conclusion:  barring the introduction of new, good
> > > > reasons for a change, the failure of the HTML5 draft to make
> > > > @alt on <img> an across-the-board requirement (even if sometimes
> > > > it has the value of &quot;&quot;) is a bug.
> > > >
> > >
> > > Hixie's email on the matter and my previous email(s) on the matter
> gave a
> > reason:
> > >
> > > A piece of software gets images from somewhere and puts them
> automatically
> > out on the Web. What should the developer of that piece of software
> program
> > it to do when an image arrives from whatever pipe they arrive from
> without
> > alternative text? How do you require a program to emit something it
> simply
> > doesn't have without faking it with junk?
> > >
> > > (Note: Saying that the program should block until human intervention
> won't
> > be a viable approach. A product that did that would only be supplanted
> by
> > products that don't. Saying that such products should be programmed to
> > output invalid HTML isn't a viable answer, either. Saying that the
> program
> > should emit alt='' would lose information about lack of data vs. marking
> the
> > image as decorative.)
> > >
> > > Should I conclude that you don't count the reason as a good reason?
> > >
> >
>
> > I assume that the WCAG wants the alt attribute to be required, so that
> > validators must throw an error for it and force web page authors to
> > explicitly consider the attribute and a proper value for it.
> >
> > Without error message, page authors will not consider the alt attribute,
> > even when there is no technical reason why their images can't contain it
> (as
> > the spec mentions in its prose).
> >
> > I have to say I agree with this reasoning.
> >
> > By specifying an alt="" attribute, the use case that you mention is
> still
> > served. At least the page author will have considered the attribute, and
> the
> > choice to not provide one was a conscious choice. I do not think the
> > distinction between 'irrelevant image' and 'no alternate text available'
> > that you provide is very valuable to the end-user, and especially not
> worth
> > the trade-off.
> >
> > ~Grauw
> >
> > --
> > Ushiko-san! Kimi wa doushite, Ushiko-san nan da!!
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Laurens Holst, student, university of Utrecht, the Netherlands.
> > Website: www.grauw.nl. Backbase employee; www.backbase.com.
>
> >
> >
> >
>
>
> --
> 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 Friday, 11 April 2008 13:30:16 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 9 May 2012 00:16:14 GMT