[Athen] PDF Accessibility questions

Sean Keegan skeegan at htctu.net
Tue Jan 23 11:05:14 PST 2007


Hi Kathy,


> I am working with an MIT department that uses a lot of PDF files and am

trying to help

> them get the "cleanest" PDF files possible.


Not sure if I quite understand what you mean. Do you mean a PDF document
that is "tagged" according to a certain specification or do you mean a PDF
document that works with assistive computer technology (or a bit of both)?


> Sometimes, after running the accessibility check, I get an error message

that "Acrobat

> was unable to make this document accessible because it could not save page

structure

> (incorrect structure was found in PDF file). Could not save changes."

Have you ever

> received a similar message and what did you do?


I am assuming that you are referring to the Accessibility Checker in AA 7.
The short answer is that I tend to avoid using the accessibility checker -
yes, it has gotten better, but it still gives a lot of "You may need to
check this" type responses. Also, you can get messages like "Provide
Missing Unicode Encodings" and this cannot be fixed from within AA - not
very helpful.

I prefer to save the PDF document as a Text (Accessible) file and then open
the file in a text editor/word processor. I spot check the document as to
where I have concerns with the reading order of the content. Content that a
screen-reader may interpret will be identified in brackets "[ ]".


> 2. After running an accessibility check, sometimes I get a message that

"there are x > number of words with characters that do not map to Unicode."
....Any possible

> solutions or suggestions on this?


How are you creating your PDF documents? If I begin in something like MS
Word (or InDesign) and go to PDF, I do not seem to encounter this issue.

I suppose I am asking: What is your workflow for PDF document creation for
both text and math-based documents?


> 3. I've also gotten error messages that say, "x number of elements were

not contained

> within the structure tree." Say what?


Wow - very helpful message. I have gotten this once before where some page
content could not be added to the tagged structure. It was not text-based,
so that may have been the problem (AA could not identify what it was).


> 4. I've also run OCR on a PDF that looked like it was an image only PDF

with some

> math notation. When I have run an accessibility check on the allegedly

OCR'ed file,

> the report says there are no problems, which is hardly the case when there

is math

> notation.


Hmmm - I am not sure I understand. Was there text on the page? Did that
content get OCR'ed correctly or did nothing get recognized? Do you have an
example I can play with?

It sounds as if you are attempting to create PDF documents containing math
notation AND have these documents be accessible. I am not aware of any
assistive computer technologies that can read native math equations within a
PDF document. I know that Design Science was interested in doing some work
on this, but I do not know how far they have progressed.

Take care,
Sean

Sean Keegan
Web Accessibility Instructor
High Tech Center Training Unit of the California Community Colleges


-----Original Message-----
From: athen-bounces at athenpro.org [mailto:athen-bounces at athenpro.org] On
Behalf Of Kathleen Cahill
Sent: Tuesday, January 23, 2007 8:32 AM
To: 'Access Technologists in Higher Education Network'
Subject: [Athen] PDF Accessibility questions

Dear Colleagues;

I am working with an MIT department that uses a lot of PDF files and am
trying to help them get the "cleanest" PDF files possible. I would love to
get some feedback from those of you who regularly use the Adobe Acrobat 7.0
accessibility checkers and do lots of tagging and alterations of document
structure.

I have some questions regarding files that originate in Microsoft Office or
Latex format (full of math notation):

1. Sometimes, after running the accessibility check, I get an error message
that "Acrobat was unable to make this document accessible because it could
not save page structure (incorrect structure was found in PDF file). Could
not save changes." Have you ever received a similar message and what did
you do?

2. After running an accessibility check, sometimes I get a message that
"there are x number of words with characters that do not map to Unicode."
Acrobat suggests the user use a different font, recreate the PDF with a
newer version of Distiller or use the latest Adobe Post Script driver to
create a Post Script file, then a new PDF file. Usually, this error message
come through on a document with lots of math notation. Any possible
solutions or suggestions on this?

3. I've also gotten error messages that say, "x number of elements were not
contained within the structure tree." Say what?

4. I've also run OCR on a PDF that looked like it was an image only PDF
with some math notation. When I have run an accessibility check on the
allegedly OCR'ed file, the report says there are no problems, which is
hardly the case when there is math notation.

If you have suggestions for me to try or know of any folks at Adobe I can
contact, I'd greatly appreciate it.

Thank you,

Kathy Cahill

**************************
Kathleen Cahill
MIT ATIC (Adaptive Technology) Lab
77 Mass. Ave. 7-143
Cambridge MA 02139

(617) 253-5111
email: kcahill at mit.edu



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