[pdftex] making pdf document accessible using LaTeX

Ross Moore ross at ics.mq.edu.au
Wed Nov 14 21:19:28 CET 2007

Hi Neil,

On 15/11/2007, at 5:39 AM, Neil Soiffer wrote:

>> 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.

Back in 2002, I developed a method to include the TeX source of  
as popup text-fields in a PDF, generated by pdfLaTeX. As the mouse  
tracks over
the displayed mathematics, a button appears to toggle show/hide of  
the field.
Furthermore, the fields are searchable, so I added a simple search  
and Javascript methods to implement searching.

I called this technique  serendiPDF , and showed an example at TUG  
2002, India.
The attached PDF is the example that I used there.

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> 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).

My methods are a bit clunky.
A lot of time is spent reprocessing the math source, to make it safe for
inclusion as text-fields in PostScript/PDF strings, as well as valid for
use with Javascript. But computers are roughly 10 times faster now, so
it shouldn't be so noticeably slow on a real-world document with lots
of math for scientific purposes. Of course it also adds significant  
size to the PDF. (I've not tried it with the latest pdfTeX, which can
do more compression, yes?)

> 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.

This applies to my methods too; and that was a major motivation.

(But it didn't seem to attract much attention at the time,
so now I use the methods mostly with images of committee members,
to pop-up in meeting minutes, so you can see who was present and
making the comments that were recorded.
BTW, James Quirk helped me to make these images draggable,
to avoid obscuring what you want to read.)

> 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..

Similarly here, but for TeX-aware applications.

> 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.

This is an aspect of TeX & mathematics that I'd like to get back into...

> 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.

   ... so would be more than happy to correspond and share ideas.
Furthermore, I have access to large amounts of math abstracts,
which would serve as an ideal test-bed for this kind of thing.

> Neil Soiffer
> Senior Scientist
> Design Science, Inc.
> www.dessci.com
> ~ Makers of Equation Editor, MathType, MathPlayer and MathFlow ~



Ross Moore                                         ross at maths.mq.edu.au
Mathematics Department                             office: E7A-419
Macquarie University                               tel: +61 +2 9850 8955
Sydney, Australia  2109                            fax: +61 +2 9850 8114

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