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From: Leo Smith
Date: Sep 17, 2001 6:30AM

Michael,
I actually heard of this technique on a web developers listserv that I
belong to. As far as I understand it, I think this is how it goes:
As has been discussed, with images turned off in a browser, the alt
text or title text for each hotspot does not display - only the alt text
for the actual image used for the image map does. I am presuming
this is the reason for the W3C Priority 3 guideline saying to provide
redundant text links for each hotspot until browsers render the text
equivalents.
Instead of providing a set of visible redundant text links duplicating
each hotspot link, the transparent gif idea would be to have,
instead, transparent gifs duplicating the links. The gifs would
merely provide a placeholder for a duplication of each image map
link, with associated alt text for each gif describing which link each
gif was for. The actual gif image itself is irrelevant - it just acts as a
placeholder for the href and the alt text. Then with images off, the
alt text for these dupicate links WOULD be displayed by a browser.
As far as screen readers are concerned, as I understand it, most
readers will read alt text for the hotspots OK, whether images are
switched on or off in the browser. However, if a reader did not,
these gifs would also provide links and alt text that could be read
by a reader just like any image used as a link can be read be a
reader.
So, basicly, the transparent gifs are a way of invisibly providing the
redundant links that the priority specifies, except that they would
not be text ones, but image links. The advantages I can see from
going this route is that the page would not be cluttered with a group
of redundant text links (sometimes image maps can have a lot of
links), which might be confusing for those not requiring them.
Hope that makes sense...
Have a great week all!
Leo.
On 14 Sep 2001, at 14:14, WebAIM accessibility forum wrote:
> I still do not understand this! I know about transparent gifs
> etc..BUT and a big BUT a transparent gif is STILL an image and if the
> browser is set to not show images then why in the hell is it showing
> the transparent gifs? Anyone care to enlighten me on that one!?
>
> Hmm..It might be possibly the "title" that needs to be specified for
> the <area> element. I will have to try this later to verify it.
>
> Thank you for the information.
>
> Michael

Leo Smith
Web Designer/Developer
USM Office of Publications and Marketing
University of Southern Maine
207-780-4774