Re: Images and alternative text

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.