[Deque Ramp PE Beta] Alt text on small images
- From: Terence de Giere <tdegiere@xxxxxxxxxxx>
- To: deque-rpebeta@xxxxxxxxxxxxx
- Date: Fri, 28 May 2004 15:39:44 -0400
Denise Wolff wrote:
I cannot stand Bobby because it will give you an error message like
"image needs an alt tag" and then when you add one you get the
message "spacer image has an alt tag". Well it needs alt="". I don't
know how you would ever get a page passed by Bobby.
This brings up a point of conflict between some developers usage of
small images, such as one by one clear pixel images with alt text to
provide information that will be process by a screen reader, or text
browser. This works very well. Such an image may not be a spacer image
at all. A blind user once told me this was a great way to make a web
page accessible to blind users but not to sighted users.
The main drawback of alt text on small images seems to be with older
technology, like older Netscape browsers where it is necessary to turn
off the images to read the alt text with a screen reader, or for
imageless browsing by a sighted reader for faster download of content on
a slow connection. These older browsers did not display the alt text
fully so it could not be read completely, and if the image was very
small, none of the alt text showed at all. While ideally such images
should not be used, graphic designers are always looking for ways to
provide such additional information without having it mess up their
graphical design, and with most recent technology, tiny blank images
with alt text work very well.
We also need to remember that alt="" or alt=" " is a convention for
handling spacer and other non informative graphics so they do not render
in recent browsers and screen readers, they are not anything in any
accessibility rules or guidelines, and that these conventions fail with
some older assistive technology which speak or display the word "image"
for any image without alt text or with alt="" or alt=" ".
Based on current practices, it is not entirely reliable to assume a very
small image is a spacer image, or that it is unimportant. For example a
site that has to handle legacy assistive technology might try to avoid
all spacer images etc., but might need a couple here and there. If the
number is very small, say one or two on a page, having alt text that
says "spacer image" provides information to older technology users
without the uncertainty of no or null or black space alt text, which
will appear to them as a possible oversight. Too many such images with
alt text results in usability problems for recent technology users. Lots
of images with blank or null alt text creates usability problems for
older technology users.
Ramp PE seems to handel this well. Now I created one workaround link to
a web page, basically to get a search engine to follow the link. The
image was 1x1 pixel in a link, had a title attribute, but had null alt
text; Ramp PE reported "invalid text equivalent for an image". The alt
text was null because I did not want it indexed, or read in a screen
reader, and the title text would be seldom processed by many
technologies. It was an experiment. The image purposely had no text
equivalent, but the title attribute provided information for another
purpose such as identification of the purpose of the image irrespective
of its informatin value, and should someone be able to read the title
text, it would do no harm.
Terence de Giere
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