Posts in Category "PDF"

September 23, 2014

PDF accessibility starts with the author

PDF accessibility is a popular topic around here. We believe access to the universe of PDF documents out in the world is critically important to users with disabilities, and we try where we can to help authors make PDFs as accessibly as possible using Adobe Acrobat and other products we make.

Freedom Scientific recently announced a beta version of their flagship screen reader, JAWS 16. In that release, their Convenient OCR (optical character recognition) feature has been expanded to help take inaccessible PDF documents (for example, paper documents taken directly from a scanner) and make them readable to screen-reader users. In light of this news, we want to caution creators of PDF content regarding what this new feature means for PDF accessibility.

Authors frequently ask us to automate this process for the thousands, millions or billions of documents they’ve already produced, and while tools do exist to do this, there’s no guarantee that they can be 100% effective at what they do. Likewise, tools like Convenient OCR, made for readers to access previously inaccessible content, all have their own limitations.

None of these tools is a silver bullet. Neither automated authoring tools nor assistive technology for readers is intended to relieve creators of PDF content from their responsibility to make that content accessible.

The PDF format, along with tools which implement the PDF/UA specification, have many features intended to enable a final PDF document that works for users on the devices they choose, with the software they choose, and with the accessibility features they prefer. No matter what technology may come along, authors know more about the structure and content of the document than any algorithm can.

The Convenient OCR feature is what’s known in accessibility as a repair technique. As with most other things, when you have to repair something, it means you’re starting with an item that is broken. This is true of inaccessible PDF documents: for example, when a page is scanned into a PDF without being properly tagged, readers miss both the textual content and the document structure that sighted users take for granted. When a tool tries to repair that document, it can only guess at the original text (and we know first-hand that OCR still isn’t 100% effective) and what kind of structure was intended.

Authors alone have the ability to communicate exactly what they mean, in a way that can be read by people with perfect vision, or who use a screen reader, or who use magnification software and/or features like high-contrast mode to adapt to their individual needs.

None of this is intended to take away from the work that Freedom Scientific is doing. Repair techniques are invaluable tools, and features like OCR have been used to work around inaccessible text since the 1970s. We feel this is a great feature for JAWS users. And other assistive technology companies such as Dolphin and AiSquared have also built tools to make text found in graphics readable to their users.

But for authors, the rules don’t change. We have lots of tools and tips on how to create accessible PDF documents that can be used by people of all kinds of abilities and preferences, and it’s still our responsibility to use them.

8:19 AM Permalink
June 25, 2013

What is PDF/UA all about, anyway?

The PDF/UA (“Universal Accessibility”) specification, or ISO 14289, published by the International Organization for Standardization (ISO) in August of last year, was a big step forward for authors of the tools we use to create and consume PDF content. But what the spec itself does is a little harder to explain, and there’s been a lot of confusion. I even confused myself recently about what PDF/UA does and doesn’t specify. So I thought it might help to summarize the spec in some detail for those who are coming to grips with its place in the world of PDF accessibility.

If the PDF/UA specification could be summed up in one sentence, it may go something like this:

“PDF/UA makes certain that the PDF format isn’t the source of accessibility problems.”

The end result of a document built using the PDF/UA spec is a more reliable, more accessible document that avoids the tricks and traps that PDF can present. PDF authors don’t need to know anything specific about what goes on behind the scenes; the tools themselves are responsible for adding and preserving the accessibility of the PDF. That’s the value of PDF/UA.

That does not mean that a PDF/UA-compliant document will always be perfectly accessible—issues like poorly-built Word documents or other source material will, of course, carry their accessibility flaws no matter what format they’re converted into. No one should claim that PDF/UA conformance means that a given document will pass the Web Content Accessibility Guidelines (WCAG) 2.0, and organizations shouldn’t treat PDF/UA as a WCAG stand-in. But conformance does indicate that the authoring process for a given piece of content retains its accessibility level when it’s output as a PDF.

The PDF/UA specification defines conformance for three different aspects of PDF: content, readers, and assistive technology. The authoring tools are intentionally omitted: only the content they produce matters here, and that can only be measured at the individual document level.

We’ve seen a number of organizations that are specifying PDF/UA-compliant documents, and that’s a worthwhile approach, as far as it goes. The revamped accessibility checker in Adobe Acrobat Pro XI bases its tests on PDF/UA and WCAG criteria, but doesn’t yet fully test PDF/UA compliance.

The PDF/UA document itself is 23 pages, and thanks to ISO’s publishing model, it’s about $90 US to purchase a copy. We’re sensitive to the cost issue here, but in the interest of full disclosure, Adobe doesn’t own this work (it was the product of participants from a number of companies, and its copyright belongs to ISO), so we’re not able to simply republish the spec. To those who are planning to implement PDF/UA in their readers and assistive technologies, $90 is not a barrier (and if you promise to implement PDF/UA in an open-source tool, I’ll buy you a copy myself, though I’m sure I’d get the better end of that deal).

The material is what we in America call “inside baseball”—it’s very technical, requires a solid understanding of PDF internals, and is heavily cross-referenced with ISO 32000-1:2008, the PDF 1.7 specification. If your goal is to author accessible PDFs, this is not the spec for you; you’re better off looking at the PDF Techniques for WCAG 2.0. However, I’ve taken the liberty of summarizing this spec so that everyone has a chance to understand what conformance entails.

The spec starts by listing what PDF/UA does not do: help with converting paper or electronic documents to PDF/UA; give implementation advice for rendering PDF documents; or tell you how to store PDFs or what OS to use. The rest of the front matter includes normative references to WCAG 2.0, PDF 1.7, PDF/A-2, and PDF/X-1a; defining a handful of terms; and setting a namespace for PDF/UA metadata which goes into every conforming file.

The document then defines conformance at three levels: individual files, PDF readers, and assistive technology.

Conforming files

A conforming file contains features that are valid according to the PDF 1.7 spec, except for features PDF/UA specifically forbids. It has to be marked as a PDF/UA document as described in Section 5, and meet all the requirements in Section 7 below.

Conforming reader

A conforming reader must also be a conforming reader according to PDF 1.7. It will support all the tags, attributes and key values specified for accessibility, and respect when optional content is hidden. It will make the logical reading order available. It will allow AT to inspect artifacts, and its interface must itself be accessible, and not interfere with any AT feature.

There are some repair techniques for headings and tables, rules for handling optional content, attached and embedded files, digital signatures, actions, metadata, navigation, annotations, forms and media.

Conforming assistive technology

A conforming AT supports all of the features of the content and the reader, and should allow navigation by page labels, document structure, or the outline. It should also let the user override default navigation zoom. (A combined reader and AT, perhaps something like TextHelp’s PDF Aloud, could be both a conforming reader and a conforming AT.)

File format requirements

This is the meat of the spec, and there’s some good advice in here for those of you who are already well-versed in tagging PDFs.

All PDF/UA documents must be tagged PDF. Tags must be semantically appropriate (that is, you can’t just mark everything <p> and be done), and in logical reading order. Artifacts (sometimes referred to as “Background” in Acrobat) must not be tagged. If a PDF does anything non-standard with its tags, those tags have to be remapped to standard PDF tags. Standard tags can’t be overridden.

Content can’t flicker, blink or flash, and it can’t be conveyed solely by color, contrast, formatting,  layout or sound. Image-only PDFs may be created, but their content must also be tagged.

The document must have a title, and it must be displayed in the title bar.

Text must be Unicode. The document’s language, and any changes in language, must be declared.

Graphics must be marked up with the Figure tag, and must have alt text, unless it’s presentational, in which case it’s an Artifact. Groups of images that represent one thought are to be tagged as a single Figure. Captions that go with figures must be tagged as such.

Headings must be nested sequentially (e.g., H1-H2-H3 is acceptable, but H1-H3 is not). Headings can go as deep as necessary (e.g., H1041 is valid, if you’ve used the first 1040 levels). Generic “H” headings are acceptable, but can’t be used interchangeably with numbered headings.

Tables should have headers (“TH” tags) with a Scope attribute.

Lists must be marked up appropriately.

Math equations must be in a Formula tag, with alt text.

Page headers and footers must be marked up as Pagination artifacts, so they’re not read out repeatedly.

Footnotes and endnotes must be marked up with the Note tag.

All optional content configuration dictionaries (a PDF feature which allows content to be hidden conditionally) must be named.

Any embedded files must also be accessible.

Article threads (which allow multicolumn layouts across pages) must retain proper reading order.

Digital signature form fields must be laid out accessibly.

Non-interactive forms have to be tagged with PDF “PrintField” attributes so they will appear as read-only form fields to AT.

Static XFA-based forms are allowed. Dynamic XFA forms are not.

Secured documents must allow AT access.

Documents should have outlines that reflect the reading order and nav hierarchy.

Visible annotations must be represented in the right place in the reading order.

Tab order must be defined.

Links must be tagged, and contain an alternate description.

Metadata tags must be properly set for embedded media.

Actions (i.e., scripting) are allowed. Changes in content or focus must be announced to AT, and cannot set time limits on individual keystrokes.

There are requirements for the implementation of fonts that are well out of scope for an overview, but important for reliable rendering of fonts across operating systems and reader implementations.

Conclusion

So, that’s it. We’re hoping a little transparency regarding PDF/UA helps everyone understand what it does and doesn’t do. In time, we anticipate that PDF/UA will make accessible authoring a more automatic and uniform process across authoring tools, which in turn will make the accessibility of PDFs in the wild a lot better in general.

1:45 PM Permalink
March 21, 2013

Slides from CSUN 2013 presentations

Here are PDF versions of our presentation slides from the CSUN 2013 conference:

6:06 PM Permalink
January 14, 2013

Free Webinar: “Exploring Electronic Document Accessibility”

Adobe is offering a free webinar on document accessibility in conjunction with SSB BART Group and FedInsider News. The webinar will take place Wednesday January 23, from 1:30-2:30 (US eastern time zone).

Jon Avila from SSB BART Group will lead the session which will target managers and content authors in addressing the following topics:

  • Overview of accessibility requirements relevant to document creation.
  • Guidance on how to analyze known problems in existing documentation.
  • Proper use of native document creation software.
  • Techniques for finding and fixing accessibility violations.
  • Best practices to maintain and update document creation processes to ensure ongoing accessibility.

You can read a more information about the webinar and register at http://solutions.adobe.com/?elqPURLPage=114. Please join us for this event!

Update: I neglected to mention it, but the webinar will have live captioning.

Update: The webinar recording is available.

9:00 AM Permalink
January 3, 2013

Acrobat XI Accessibility Documentation

On behalf of the Adobe Accessibility team, I’d like to welcome you all to 2013. We’ve got a big year ahead of us, and we’re starting with some new documentation for Acrobat XI.

We’ve updated our Acrobat accessibility training resources page with four new PDFs:

PDF Accessibility Overview
Covers the accessibility features of PDF as a document format, as well as Adobe Acrobat and Adobe Reader.
Using the Acrobat XI Pro Accessibility Checker
A complete walkthrough of Acrobat XI’s Accessibility Checker, as well as the Make Accessible action wizard.
Acrobat XI Pro PDF Accessibility Repair Workflow
Walk step-by-step through the PDF accessibility process in Acrobat XI.
Acrobat XI Pro Accessible Forms and Interactive Documents
Create interactive forms that can be used by anyone, ensuring privacy and independence for all.

We’ve also created a Acrobat XI accessibility best practices document which contains all four of the above guides in a single file. Documentation for Acrobat versions 8 and up can be found on the training resources page as well.

The new features of Acrobat XI are intended to make creating PDF documents both easier and more automatic. The Make Accessible action wizard walks users through a number of steps, like running optical character recognition and prompting for alternate text on images, and then tests the final product. This makes the process for editing and testing for PDF accessibility a fast, uniform process for authors of all skill levels. The built-in accessibility checker has also been improved, including testing support for the Web Content Accessibility Guidelines (WCAG) 2.0. We think this is the most substantial improvement in Acrobat accessibility since we added support for assistive technology back in 2002.

The team is looking forward to giving a detailed Adobe Acrobat XI walkthrough at the 28th Annual International Technology and Persons with Disabilities Conference on February 28th, and at other conferences throughout the year. We hope you’ll find these tutorials useful.

5:31 AM Permalink
October 1, 2012

Acrobat XI Accessibility Changes

Acrobat XI (pronounced “Acrobat Eleven”) is coming soon, and with it a host of new accessibility features that will help authors produce more accessible PDF documents, with less effort.

Key improvements in Acrobat include the addition of the Make Accessible Action, enhancements to the Touch Up Read Order Tool, and improvements to the accessibility checking tool to guide authors testing against WCAG 2.0 and PDF/UA.

The Acrobat team has more information about accessibility in Acrobat XI posted, and more information is coming soon.

10:07 AM Permalink
May 20, 2012

Adobe Support for Open Source Assistive Technology

Adobe continues our support for NVAccess development of the NVDA screen reader in 2012, and with that funding we are supporting a number of priorities designed to help NVAccess developers continue to offer an up-to-date tool for end users as well as developers seeking to provide accessible applications and web sites. Included in the list of priorities is support for ongoing improvements to NVDA’s ability to interact with PDF documents, AIR applications, and ebooks read in Adobe Digital Editions, and for general HTML and ARIA improvements.

For PDF specifically, we recognize the value of NVDA supporting the upcoming PDF/UA standard (ISO 14289) and have agreed with NVAccess that the PDF-focused portion of the work should be focused on enabling NVDA to become a PDF/UA compliant assistive technology.

Past improvements to NVDA’s support for PDF have brought significant benefits for NVDA users reading PDF documents. These past improvements were not designed to focus on PDF/UA compliance, but most of the improvements serve to accomplish compliance and dovetail nicely with current efforts focused on the new standard. The work to make NVDA compliant with PDF/UA will not be able to be completed in the current year, as the scope of work is beyond what can be completed within the current year’s funding, but we expect to be able to provide details about progress in the coming months. As support for PDF/UA is an important goal, we will seek ways to offer support to NVAccess in future years also.

We are almost halfway through the year for this funding and NVAccess developers have made continual improvements – we encourage screen reader users and accessibility-interested developers to download the latest release of NVDA to read ebooks, test web pages, read PDF documents, and more. NVDA is a great tool and Adobe is pleased to help support its development.

Update: We should also clarify that our support for NVDA does not come at the expense of support for other assistive technologies. Tools such as Claro Read, JAWS, Supernova, Window-Eyes, ZoomText, and many more are important tools that users depend on and we will continue to work with the vendors of these great tools.

9:43 PM Permalink
May 7, 2012

WCAG 2.0 and PDF/UA

Harmonization of accessibility standards is a primary goal for Adobe which is why for many years Adobe has worked on the W3C Web Content Accessibility Guidelines (WCAG) working group – our participation was driven by a desire to help define a WCAG 2.0 standard which would be useful for web content that Adobe tools are involved with the authoring or display of, including PDF, Flash, HTML, and more. There is great benefit for developers, authors, and end users when there is an agreed on standard for what constitutes an accessible experience, and it is encouraging to see that WCAG 2.0 is regarded as the primary standard for web accessibility and is referenced by national governments around the world. However, there is more to achieving accessibility than the normative text of WCAG 2.0.

In 2004, Adobe and AIIM started the PDF/UA (Universal Accessibility) activity with the intent of producing standards specific to PDF authoring and presentation which ensure that conforming PDF (ISO 32000-1) files are accessible and usable to all, including users who rely on assistive technology. Today, PDF/UA is ISO 14289-1, a “Final Draft International Standard (FDIS)”, expected to be published later in 2012.

We’ve received many questions about the relationship between PDF/UA and WCAG 2.0. WCAG 2.0 was developed as a technology-independent standard and provides individual (normative) success criteria for accessibility which are general enough to apply across technologies. The W3C’s WCAG working group also provides a growing collection of advisory (non-normative) techniques to offer technology-specific guidance, including a growing set of techniques for HTML, CSS, Scripting, PDF, Flash, and more. Beyond these techniques, developers need to conduct additional research to ensure that the content or applications they create meet the WCAG 2.0 success criteria – for example, a Java developer looking to offer a compliant applet will not find techniques on the W3C site at this time, but may be able to meet WCAG 2.0 if they correctly follow guidance provided elsewhere and evaluate the resulting applet against the WCAG success criteria.

PDF developers need this type of clarity on how to meet WCAG 2.0, and the PDF techniques, while useful, do not presently represent a complete set which encompass all technical requirements for accessibility in all PDF documents. This is where PDF/UA provides help. PDF/UA provides normative technical specifications for the use of the PDF format, defining proper structure and syntax to enable reliable access. This includes identification of necessary tagging structures, how to specify alternative text for images, how to ensure correct Unicode mappings for character glyphs, and many other file, page and object-level specifications, as well as how Reader applications and assistive technologies can fully process PDF/UA conforming files to maximize accessibility.

PDF/UA defines the technical specifications to enable PDF documents to meet WCAG 2.0, but WCAG 2.0 has additional requirements which require an author’s attention. The areas where WCAG 2.0 has additional requirements include time-based media (guideline 1.2), scripting and actions (e.g. success criteria 3.2.1 and 3.2.2), and certain types of content (e.g. success criteria 2.4.4). For these and other additional requirements, the W3C’s technique documents (both general and PDF-specific techniques) provide guidance for authors interested in complying with WCAG 2.0.

PDF/UA clarifies and simplifies the PDF-specific technical requirements to meet WCAG 2.0. Adobe fully supports PDF/UA and intends to use and promote it in our PDF authoring tools. Adobe also plans to support the conforming Reader requirements, which are part of PDF/UA. Authors using Adobe tools such as Adobe Acrobat will be enabled to support PDF/UA as a first and major step toward compliance with WCAG 2.0.

9:00 AM Permalink
January 3, 2012

WCAG 2.0 Techniques for PDF

Authors looking for additional guidance on how to meet the W3C WCAG 2.0 for PDF documents can now look to the W3C techniques repository for additional guidance. Techniques for PDF authored over the past two years since the release of the last update to the WCAG techniques (which included techniques for Flash) are now part of the larger collection of techniques. View the full set of WCAG 2.0 techniques or view PDF techniques on their own.

These techniques provide a clear path for demonstrating that a PDF document can meet the most current accessibility standard from the W3C.

As with the Flash techniques for WCAG 2.0 and techniques for all other technologies, the PDF techniques are presented as examples which the WCAG Working Group viewed as sufficient to meet WCAG 2.0 success criteria, not as the only way to meet any given success criteria. Authors may discover a new way to address a success criteria, in a way not yet covered in the existing techniques, and be able to demonstrate why it is sufficient. The techniques offer a collection of strategies that have been reviewed by the working group, but the techniques collections for all technologies are works in progress as there are always additional ways to address success criteria.

The table below provides a listing of the WCAG level A and AA success criteria and the PDF-specific and General techniques that authors can employ to meet success criteria. It is worth noting that not all success criteria for WCAG 2.0 have technology-specific techniques. For example 1.3.3 (Sensory characteristics) has only general techniques, and in this case and similar ones I reference the relevant general techniques section. In some cases there are relevant general techniques as well as PDF-specific techniques and for these both are linked.

Update: I neglected to acknowledge the hard work of Mary Utt from The Paciello Group on the PDF techniques initially, but Mary was a tremendous help in moving this work forward and I offer many thanks. Many people on the WCAG working group also worked very hard to help make these techniques reach this final stage. Thanks to all!

Please send general comments, comments or questions on the techniques, or suggestions for new techniques.

WCAG 2.0 Success Criteria and Applicable Techniques for PDF
Success Criteria Level Techniques
1.1.1 Non-text Content A
1.2.1 Audio-only and Video-only (Prerecorded) A
1.2.2 Captions (Prerecorded) A
1.2.3 Audio Description or Media Alternative (Prerecorded) A
1.2.4 Captions (Live) AA
1.2.5 Audio Description (Prerecorded) AA
1.3.1 Info and Relationships A
1.3.2 Meaningful Sequence A
1.3.3 Sensory Characteristics A
1.4.1 Use of Color A
1.4.2 Audio Control A
1.4.3 Contrast (Minimum) AA
1.4.4 Resize text AA
1.4.5 Images of text AA
2.1.1 Keyboard A
2.1.2 No Keyboard Trap A
2.2.1 Timing Adjustable A
2.2.2 Pause, Stop, Hide A
2.3.1 Three Flashes or Below Threshold A
2.4.1 Bypass Blocks A
2.4.2 Page Titled A
2.4.3 Focus Order A
2.4.4 Link Purpose (In Context) A
2.4.5 Multiple ways AA
2.4.6 Headings and Labels AA
2.4.7 Focus Visible AA
3.1.1 Language of page A
3.1.2 Language of parts AA
3.2.1 On Focus A
3.2.2 On Input A
3.2.3 Consistent Navigation AA
3.2.4 Consistent Identification AA
3.3.1 Error Identification A
3.3.2 Labels or Instructions A
3.3.3 Error Suggestion AA
3.3.4 Error Prevention (Legal, Financial, Data) AA
4.1.1 Parsing A
  • Not Applicable: PDF is not implemented using markup languages
4.1.2 Name, Role, Value A
10:49 PM Permalink
June 29, 2011

InDesign 5.5 Accessibility Webinar

Just a heads up that Noha Edell from Adobe is offering a webinar on InDesign CS5.5 accessibility, this Friday, July 1 at 3pm Eastern/12pm Pacific.

The InDesign team has made substantial improvements in accessibility support. Authors now have complete control over generated reading order, can provide tables and lists that are tagged correctly without any need for repair in Acrobat, and have more sophisticated support for alternative text for images.

This webinar is a must-see for anyone who uses InDesign for the creation of PDF documents that need to be accessible. The webinar is Friday, July 1, at 12 p.m. PT at http://my.adobe.acrobat.com/askcspro.

More information about the event is available at http://www.facebook.com/event.php?eid=198681246846060.

1:56 PM Permalink