[pdftex] making pdf document accessible using LaTeX
Neil Soiffer
NeilS at dessci.com
Wed Nov 14 19:39:38 CET 2007
> By the way, I have been pointed to a developing NISO standard for
> accessible maths, that would be similar to this with MathML, if I
> understood well. A variation of Design Science's MathPlayer would have
> been able to read aloud such a PDF, including the maths read not as ASCII
> source, but as real maths.
I think the standard you are referring to is the DAISY+MathML spec. It is
available at
www.daisy.org/projects/mathml
Another effort people might be interested in is PDF/UA (Universal Access).
This AIIM committee that is working on developing an ISO standard for
accessible PDF. See www.aiim.org/standards.asp?ID=27861. Part of that work
involves making sure that math in PDF is accessible. It does this by
tagging the math with MathML.
In general, tagging PDF is the key to accessibility. That goes for math and
for the rest of the document. You can add TeX using "ALT" and most screen
readers will pick this up. This is useful for users of screen readers who
are also TeX users, but that is not a very large community. Still, it is
much better than nothing, although it doesn't begin to offer the
accessibility advantages of tagging the math with MathML (customizable
speech, braille generation, synchronized highlighting, ...). When connected
to screen readers (or TTS engines directly), speech cues/prosody info can be
part of the generated speech string. You can't do this when using the ALT
tag.
We (Design Science) have a beta of an Acrobat/Adobe Reader plug-in that does
all of that, but the lack of tagged PDF means there is no market for this...
even when we give it away (like MathPlayer).
Lots of scientific documents are distributed as PDF, and of course, most are
authored with TeX. It would be a huge boon for people with visual
disabilities (and this includes those with dyslexia) if pdftex could
generate the MathML tags. It would also be a boon to search engines,
especially math-aware search engines that will are being developed now (eg,
www.mathdex.com) to add tags. It is useful for everyone because it allows a
plug-in (such as the one we developed) to provide a copy of the MathML or
TeX so that it can be pasted into another document or computation/graphing
system..
The bottom line is that tagging the document is the right thing for pdftex
to do. Using TeX, or better yet, Web standards for math (ie, MathML) allows
for greater interoperability and benefits for everyone.
I'd be happy to answer questions on how to embed MathML into PDF if any of
the pdftex developers are interested in doing this.
Neil Soiffer
Senior Scientist
Design Science, Inc.
www.dessci.com
~ Makers of Equation Editor, MathType, MathPlayer and MathFlow ~
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