HTML techniques - Alt-texts for images (no blocker?)

In the HTML techniques document, there is a technique called "Short text
equivalents for img elements ("alt-text")":
<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-HTML-TECHS-20031020.html#img-alt>

What seems to be missing here, is the explanation of when to use null
alt-text. I remember visiting a website, built by a company who just got
interested in accessibility. They used a lot of spacer images to enforce
layout, each of which had an alt-text saying "Image used for presentational
purposes only". Can you imagine how crazy that drove their blind visitors?
This is a textbook case of when to use null alt-text. 

Another example of when to use null alt-text is when the alternative text is
already present in the page, for example if have a gallery of pictures where
the title of the image is printed below it. Another example is the combined
use of an icon and text as a link, which is discussed elsewhere on the page:
<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-HTML-TECHS-20031020.html#imagetex
tlinks>. 

Besides the lack of explanation about when to use null alt-text, I think we
need some more techniques for providing text equivalents. The WCAG
guidelines version 2 are worded such, that these last two examples I gave
count as providing a text equivalent for non-text content that can be
expressed into words. However, in the techniques document, the ALT-attribute
is the only technique that is presented to provide a text equivalent for an
image.  Reading the techniques document, I would think that I still had to
provide an alt-text for an image, even if (the same) text was already used
as a 'caption' for the image on the page. 
I think this is unfortunate and narrows the intentions of the WCAG 2
document.

Yvette Hoitink
CEO Heritas, Enschede, The Netherlands

Received on Friday, 31 October 2003 10:58:53 UTC