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Re: Is ALT text necessary if there's an identical caption adjacent?

From: David Dorward <david@us-lot.org>
Date: Fri, 30 Jul 2004 16:14:33 +0100
Message-Id: <29A9748E-E23B-11D8-9CBF-000A957E4F00@us-lot.org>
To: wai-ig list <w3c-wai-ig@w3.org>

On 30 Jul 2004, at 16:04, Francois Jordaan wrote:
> There is no reason why ALT text would always be identical to a picture
> caption,

This is true

>  since the main purpose of the ALT text is to accurately describe
> the image,

This is not true. Alt text is there to provide a text alternative to 
the image. Longdesc is there to accurately describe the image (in those 
(uncommon) instances where its needed).

> while a caption can be much freer. BBC News articles are perfect
> examples of this.

... of this unhelpful practice. Take this (random article that was the 
BBC news website when I started writing this email) for example:

    Animal extremists face crackdown

    Mouse - RDS/Wellcome Trust photo
    Existing legislation will be amended

    Plans for a crackdown on animal rights campaigners who
    use terror tactics against scientists have been unveiled

The alt text doesn't make a great deal of sense in context, and doesn't 
add anything useful to the article.

> However, in the e-commerce world, pictures usually depict nothing 
> besides
> themselves, i.e. the product name. If the product name is immediately
> adjacent in plain text, I think ALT text is unnecessary.

A rule of thumb that serves me well - if you were reading the document 
out over the telephone, what would you say when you encountered the 

> (Warning: this argument is weakened if the IMG and the caption are in
> separate A tags. Because then a list of hyperlinks on the page (a
> frequently-used feature in screen readers)

Yes, this is something of an issue. Its best to try to get the images 
and text in the same anchor. Then you get fun if you want to avoid 
little underlines next to the image (which, I believe[1], is one of the 
main reasons people use separate links for this), but markup like this 
might do the job:

<a class="imgLink"> <img> <br> <span>text</span> </a>


a.imgLink { text-decoration: none; }
a.imgLink span { text-decoration: underline; }

> Accessibility dilettantes (like most clients nowadays) have gotten 
> used to
> checking for ALT text by looking for tooltips. Thus the desirability 
> of ALT
> text has been conflated with a spurious desirability of tooltips for 
> sighted
> users. This is a dangerous generalisation that we should refute
> convincingly.

I find that <http://ppewww.ph.gla.ac.uk/%7Eflavell/alt/alt-text.html> 
is helpful for this.

[1] No, I don't have any evidence of this.

David Dorward
Received on Friday, 30 July 2004 11:29:11 UTC

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