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Re: Investigating the proposed altattributerecommendationsin HTML 5


From: Andrew Kirkpatrick
Date: Aug 30, 2007 4:50PM

> in regards to the omission of the alt:
> "*When the
> alt<http://www.whatwg.org/specs/web-apps/current-work/multipag
> is missing, the image represents a key part of the content *.
> Non-visual user agents should apply image analysis heuristics
> to help the user make sense of the image."
> HTML 5 draft specification [
> http://www.whatwg.org/specs/web-apps/current-work/multipage/se

OK, reading that section again, it is referring to images that have no
equivalent and "doesn't have an obviously textual alternative". The
spec says:

In certain rare cases, the image is simply a critical part of the
content, and there might even be no alternative text available. This
could be the case, for instance, in a photo gallery, where a user has
uploaded 3000 photos from a vacation trip, without providing any
descriptions of the images. The images are the whole point of the pages
containing them.

In such cases, the alt attribute may be omitted, but the alt attribute
should be included, with a useful value, if at all possible. If an image
is a key part of the content, the alt attribute must not be specified
with an empty value.

To me this is attempting to make a rule for developers to abide by.
This is effectively saying "when alt is needed and not available don't
put null alt just to pass the validator". This is in fact pretty
interesting. AT already applies heuristics to guess at the appropriate
representation for the image, but not _image_ heuristics. This would be
nice, but we're not there yet. This could be a nice feature for
repair tools since they could easily identify images that are already
determined by the developer as needing an alt.

At the end of the day, it isn't going to make a big difference either
way. Images need useful alt values in a well-defined set of
circumstances. Whether the image alt attribute is missing or it is
alt="" for an image that is important, there is an accessibility
problem, and one that would need to be verified even if a page passes a

In the page Steve posted, the images are links. In the HTML5 document,
this case is covered in an example, but not specifically mentioned. In
their image page example, the images don't seem to be links. I'll
certainly agree that this requires clarification, but if the images that
were links were missing alt this is still and accessibility issue and
some amount of manual verification is still required to be assured of