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REVIEW: PAC (PDF Accessibility Checker) 1.1
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by Duff Johnson
Tuesday, October 26, 2010
Over nine years ago, we were first in the world to offer tagging and Section 508 compliance services for PDF files.
So you can imagine that we've been very, very interested in the subject of accessibility checker software for PDF files for a very long time.
Until recently, Adobe Acrobat Professional's Accessibility Checker was the only game in town, and that game hasn't moved in years. The last significant update to Acrobat's tagging tools was in Acrobat 7, which shipped back in January, 2005.
Astute observers will notice the distinct lack of any updates on the tagging front in the just-announced Acrobat X. As a beta-tester of the software I can assure you that if Acrobat X included improvements to the tagging tools, Adobe's Acrobat X marketing would say so, and it doesn't.
If Acrobat's PDF tagging tools development has stalled, what of other vendors? Net-Centric's Acrobat plugin, CommonLook, provides superior table-tagging tools and other options that improve on Acrobat. Nonetheless, the marketplace has so far failed to deliver a quick, easy and inexpensive way for end-users to understand what's wrong (or sub-optimal) in their tagged PDF.
Enter the PDF Accessibility Checker (PAC)
It was for this reason that we were so pleased to find the "PAC", or PDF Accessibility Checker, free software by Access for All, a Swiss non-profit foundation.
PAC is a pretty interesting, and did I mention that it's FREE?
The fundamental value of the tool as compared with Acrobat is the Preview feature, which displays the tagged content in tag order (as is only right & proper), with nice little labels when you hover over the tags. Apart from instantly being able to visualize the way in which your document appears to an Assistive Technology (AT) user, this Preview provides a quick and effective debugging tool, allowing you to quickly locate and therefore (back in Acrobat) fix your PDF's tags, mark as Artifact, or other.
While superficially similar, this feature is NOT to be confused with Acrobat's "Reflow" feature, which is nearly useless, from an accessibility perspective. (More on that in another article)
CommonLook also offers a tags-based Preview, but CommonLook isn't free, and requires Adobe Acrobat. With PAC, any user can immediately see if their PDF is usefully tagged or not.
The PAC checks for a Title, promotes the use of bookmarks and section header tags, checks for contrast, and much more. It's head-and-shoulders above Acrobat's Accessibility Checker.
But (you knew there had to be a "but"), first and foremost, the 1.1 version of the application is unreliable, and bonks on way too many PDFs. Reported errors are generally the always-informative "unhandled exception", with the close runner-up being "An error occurred because of unsupported elements."
Both of these errors occur far too often - as a result, the PAC just isn't a production accessibility tool - yet. The developers do invite users to send them files that break the software - and I'll add my encouragement to theirs!
Just like Acrobat, PAC reports a lot of "false positive" errors, including mis-interpreting artifacts as content lacking tags. On the other hand, that's one of a very few advantages (apart from reliability!) Acrobat retains over this excellent free software.
The following table compares features of Acrobat's Accessibility Checker (version 9.x) to the PAC 1.1.
|
Feature |
Adobe Systems |
Accessibility for All |
Advantage |
|---|---|---|---|
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Reliability |
The standard by which others are judged |
Poor (for now) |
Acrobat |
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Check for document title |
No |
Yes |
PAC |
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Check for bookmarks |
No |
Yes |
PAC |
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Facilitate check of logical reading order |
No |
Yes |
PAC |
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Check for the use of section heading tags |
No |
Yes |
PAC |
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Check for sufficient contrast in page content |
No |
Yes |
PAC |
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Check for incorrect tag structures |
No |
Some |
PAC (with errors) |
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Detect unmarked (untagged) content |
Yes |
Yes, see note |
Acrobat |
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Check for language setting |
Yes |
Yes |
PAC |
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Check for correct character encoding |
Yes |
Yes |
PAC |
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Validate list and table structure |
Yes (with errors) |
Yes (via Preview) |
PAC |
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Check alt. text for images |
Yes |
Yes (via Preview) |
PAC |
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Check for form fields with no tooltips |
Yes |
Yes |
PAC |
The PAC won't find all the accessibility problems in your PDF, and it can't fix the problems it does find. But it can really help PDF taggers do their jobs. Most importantly, the PAC really helps in visualizing the significance of tagging for accessibility - and thus, in highlighting how critical even "small" errors can damage the reading experience.
Sure, some of the interface includes misspellings and other detritus of early-stage software developed by those for whom English is a second language.
Here's hoping that the PAC will focus the minds of the commercially-minded, and inspire new implementations addressing the challenge of PDF accessibility. In the meantime, collect some good Karma by donating a few dollars to help these good folks continue to do their thing!
SYSTEM REQUIREMENTS: PAC is Windows software, and requires Windows XP or later along with the .NET Framework 2.0 SP2, Adobe Reader 8 or later, plus current versions of either Firefox, Internet Explorer or Google Chrome.
Learn More...
Appligent Document Solutions provides PDF tagging services and educational and training resources in the Section 508 Center for PDF.
Comments
I noticed there is now a version 1.2. Is that any more robust than 1.1? I tried 1.1 on my documents and it bombed on all of them...
Duff, on your recommendation I have tried using the PDF Accessibility Checker on a couple of our older, inaccessible PDF files. I did not encounter any of the errors you mentioned, and I found it a much more efficient way to locate problems in a nearly accessible PDF so I could go straight to them and fix them in Acrobat. That rapid feedback alone is invaluable. It's the key to making the remediation of PDFs a learnable skill rather than a random action.
How so? Because instead of plodding through a series of PDFs so slowly that my mind is numbed by the details, I was able to get through the files so fast that I could quickly see common patterns of problems. So, just as everyone knows that before Office 2007 Acrobat could not pick up the language specification from the source document (so we set that before we do an accessibility check), I started to see other things to assume were wrong in our old documents and fix before going to the trouble of running a report.
The level of detail is helpful. It's easier to tie specific actions to specific results. And the organization of the report makes it easier to follow than are Acrobat's reports. It's as if the interface has dropped out of the way of the work. From that and from some of the tips offered in the PAC's report, I have learned about features I didn't know Acrobat had. Soas I use this tool, PDF remediation is becoming easier to learn, easier to do, and easier to document.
Perhaps as I continue to use it I will discover situations in which it is unreliable. But for now, it's saving me so much time that I can easily afford to confirm its results with a full check in Acrobat whne there is any chance that something might have been missed. I wish I had known about this tool earlier. Thanks for bringing it to my attention.