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Re: how to detect images having math expressions

for

From: Steve Green
Date: Jun 4, 2008 4:20AM

I would agree with that but manually visiting every page simply isn't
practical for large websites. I was thinking that a more cost-effective
option might be to assess all the images and identify those that may need
non-null 'alt' attributes. When you find out which pages use these images it
may mean that perhaps only 10% of the pages need to be assessed for that
checkpoint.

Once you get above a few hundred pages it becomes impossible to test every
page for every checkpoint. It is not cost-effective (and may not even be
possible) to do it manually, and automated tools only do a very small part
of the job. I am interested in techniques that make better use of the
available manual resources to do things that automated tools cannot do at
all, when a brute force (i.e. view every page) approach is not an option.

Steve



-----Original Message-----
From: <EMAIL REMOVED>
[mailto: <EMAIL REMOVED> ] On Behalf Of Jukka K. Korpela
Sent: 04 June 2008 10:48
To: WebAIM Discussion List
Subject: Re: [WebAIM] how to detect images having math expressions

Steve Green wrote:

> It would probably be more cost effective and reliable to produce a
> list of all the images and have someone (this need only be a very
> cheap resource) look at them all and flag any that contain text or
> math expressions.

It would be even better to ask a human tester to evaluate all images for
accessibility. Texts that contain text or math are just a special case, and
it's probably better to work out all images in one pass. They should of
course be evaluated in context, since it is generally impossible to judge
what is an appropriate alt text just by looking at the image. (For example,
an image might be purely decorative, calling for alt="", in some context,
and a content-rich image requiring a longish textual alternative in
another.)

Jukka K. Korpela ("Yucca")
http://www.cs.tut.fi/~jkorpela/