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Re: Help on approach for annotating images

for

From: Jukka K. Korpela
Date: Dec 1, 2005 8:20AM

On Wed, 30 Nov 2005, Malcolm Wotton wrote:

> First I couldn't find how to browse the message history so I don't know if
> my main question has already be answered.

The archives can be found at http://www.webaim.org/discussion/archives
and they have a search facility (though it's often difficult to search
for information like the one you're after, since it cannot be described
a few distinctive keywords - some people would refer to annotations of
images, some to captions of images, some to titles of images, etc.).

> I've recently added ALT text to all images in a site I'm developing. For the
> normal browsing experience some images have captions (which will be
> identical to the ALT text) and some do not.

A caption should usually not be the same as the ALT text.

> Captions are implemented as
> normal text underneath the image.

That's a bit problematic, but there is no good solution, since HTML has no
markup for image captions; see
http://www.cs.tut.fi/~jkorpela/www/captions.html
I mention this because the technique used may affect the question about
appropriate ALT text. In particular, if you decide to embed the caption
into the image itself and the image is only an illustration of something
that has been explained verbally in the text, alt="" would be adequate
(somewhat debatably, since it deprives some users of access to the image
even if they could benefit from it, namely people who surf with a graphic
browser without automatic loading and display of images).

> If I browse the site with lynx for those
> with captions I see both the ALT text and the caption (ie a duplication).

Technically, that's what should be expected to happen.

> Is this acceptable?

Usually not.

> Should I remove the ALT text from image that have a caption?

Certainly not. But you might modify it. This really depends what the image
is about, what it is supposed to convey, etc. For example, if the page
contains recent news and the image is a photo of some event and the photo
shows some people shaking hands when meeting, it might be appropriate to
write a caption like "Presidents Foo and Bar met in Paris, France", but it
it would pointless to duplicate this in the alt text. Rather, you
could write alt="(photo of the meeting)". This makes the presence
of the caption text understandable when the page is presented as plain
text or as speech.

See "Captions and accessibility" at
http://www.cs.tut.fi/~jkorpela/www/captions.html#acc

See also Understanding Guideline 1.1: Provide text alternatives for all
non-text content in the WCAG 2.0 draft:
http://www.w3.org/TR/UNDERSTANDING-WCAG20/#text-equiv

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