Re: fear of "invisible metadata"

On 6/18/07, Maciej Stachowiak <> wrote:

> ALT should not be required either. It leads to pointless alt="" on
> images that have no reasonable text equivalent, just to satisfy
> conformance checkers. And that is actively harmful, because AT can't
> tell the difference between a semantically null image and a
> semantically meaningful image with no text alternative.

ALT should be required. The single most important thing a person can
do to make a web page accessible is to include alternative text for
images with alt attributes. "If there is no alt attribute at all
assistive technologies are not able to ignore the non-text content."

An alt attribute is used to specify alternative text. It is used to
replace an image. That means that it serves the same function as the
image. Users of screenreaders, language translation applications, text
browsers, or some hand-held devices cannot directly access pictures
and other graphics. Similarly, some users choose to turn picture
loading off- especially those with slower dial-in connections. These
users rely on alt attributes. When you make the decision to add
alternative text, you include the many people who use talking
browsers, screen readers, text browsers or browsers on small devices.

An alt attribute is not a label or description for the image. This is
not an immediately obvious distinction. In fact, it might seem natural
to assume that alternate text is a label or a description. It is not.
The words used should be a text equivalent and convey the same
information/serve the same purpose as the image. The aim is to provide
the same functional information that the visual user sees. The alt
text should be a "stand in" if you will if the image is missing. The
test is, when you replace the image with the text would everyone do
the same thing/receive the same information as best as possible?

Before CSS, an empty alt (i.e. alt="") was the best mechanism we had
to use for images which played only a decorative (eye candy) role in a
page. Eye candy are things that serve no purpose other than to make a
site visually appealing/attractive and (in many cases) satisfy the
marketing departments. There is no content value (though there may be
value to a sighted user).

But now days, CSS background images would be the mechanism to use for
such eye candy. HTML 5 presents an opportunity to promote the use of
the CSS W3C standard for presentation. By taking eye candy out of HTML
and putting it in CSS, utilizing  background-image,
background-position, and background-repeat you are placing the
decorative images right where they belong. Let CSS handle presentation
and HTML provide the structure and semantically marked up content.

Separate content and style. Like the Architecture of the World Wide
Web Spec says, "A specification SHOULD allow authors to separate
content from both presentation and interaction concerns." [2]
Separating content from presentation is a major step forward in
creating accessible web sites.

So my suggestion is to require alt for ALL images. But discourage the
use of  eye candy images in HTML, instead recommend and promote the
use of CSS for such purposes. Perhaps even consider _gracefully_
degrading empty alt/eye candy in an orderly manner.

Best Regards,


Laura L. Carlson

Received on Thursday, 21 June 2007 16:32:01 UTC