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Re: Images and alternative text

From: John C. Vernaleo <john@netpurgatory.com>
Date: Thu, 7 Aug 2008 16:09:53 -0400 (EDT)
To: Ian Hickson <ian@hixie.ch>
Cc: Philip Taylor <pjt47@cam.ac.uk>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <alpine.DEB.1.00.0808071605480.22567@ganon.vernaleo.dyndns.org>

On Thu, 7 Aug 2008, Ian Hickson wrote:

> On Thu, 7 Aug 2008, Philip Taylor wrote:
>>   <img src="..." alt="{x \over y} = {1 \over {y \over x}}">
> ...would be a horrific alternative text to give a screen reader.
> I don't think it's equivalent to the image at all. It's the source of a
> program that was used to generate the image, but that's not the same
> thing. Would you consider the replacement text of a fractal to be the C
> source code that generated it? Or the replacement text for an SVG file to
> be the raw source code of that SVG file?
> Correct alternative text for an image generated by LaTeX is a textual
> representation of the expression generated from the same LaTeX.
> e.g.:
>   <img src="..." alt="The fraction x over y is equal to 1 divided by the
>   fraction y over x.">

I don't know much about screen readers, but I do know something about 
LaTeX, and I just don't see how the textual representation of equations 
scales very well past very simple equations.  Even in the example here 
that sentence is just barely unambiguous.  A more complex equation would 
be much worse and a matrix basically impossible.  And I'm not convinced a 
human could do it any better than a program could.

At least the version that was close to the LaTeX code still contained the 
relevant information in a way that is mostly parsable by a human.
Received on Friday, 8 August 2008 09:51:11 UTC

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