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Re: ALT Text - CMS Problem

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From: Jukka K. Korpela
Date: Apr 18, 2011 3:39AM

Joshue O Connor wrote:

>>> 1. An image of a red ball on a page is given alt="b47_257.jpg"
>>> 2. An image that shows where to find the routing number on a check
>>> is given alt=""
>>
>> We know that (1) is wrong. While (2) might be wrong too, it is
>> difficult to say which one would be more wrong.
>
> It's not difficult from an AT perspective, as IMO the first is 'more
> wrong' as it could interfere with the user experience in a more
> negative way.

As immediate user experience, it is certainly worse to hear some meaningless
sequence of characters pronounced than hearing nothing. But there's much
more than that. While (1) unduly causes some rubbish to be presented to some
users, (2) prevents some users from getting some crucial information at all.
So basically it is disturbing noise vs. deprivation of information.

What makes the relative wrongness difficult to judge is that the context may
make (2) far less serious than it looks like. As you mention, the image
might be redundant in the sense that it only visualizes some instructions
that are given in text elsewhere on the page. Then alt="" would be
_correct_, though we might ask whether alt="(An image illustrating how to
find the routing number.)", as it might be relevant to know that there is
such an illustration, even if the user cannot himself see it.

> The bad alt is more actively useless than having a null
> alt that removes the image from the DOM.

Technically, the image is not removed from the DOM - the alt="" attribute
does no such thing. From the DOM perspective, it simply adds the alt
property to the object corresponding to the element.

> Unless it's a functional
> image that is vital to complete some task etc and then no alt, is
> better than poor alt and also better than null alt.

The most serious accessibility problems with images relate to vital images
that lack an appropriate alt attribute. It's a nuisance to have to listen to
alt="b47_257.jpg", but the crucial question is: how do you cope with it, as
a user? If the value is really "red-bullet.jpg", you might guess that it's
just some bullet that has no significance apart from possibly indicating the
subsequent text as an item in a list. And there's definitely the chance that
you will suspect that it's really a significant content image and try and
find _some_ way on understanding its meaning. (E.g., you might ask a friend
for help, or you might complain to the site administration, or maybe, if you
are visually impaired, you might have some chance of understanding some
images - after opening the image, assuming you normally browse with images
disabled.)

Compared with this, alt="" removes the image from the _imageless rendering_
of the page. So with images switched off, you would not even notice it - you
would have no hint of the presence of an image that might carry crucial
information, or just relevant information, though it might be irrelevant
too.

--
Yucca, http://www.cs.tut.fi/~jkorpela/