This is the third in a series of articles about accessibility and office documents. In this article we’ll discuss the usage of Adobe Acrobat Portable Document Format (PDF) files and methods for ensuring they are accessible to people with disabilities. In future articles we’ll discuss PDF forms, web site development, and web applications and accessibility.
Note: This article was first written in early 2008. The text was re-edited and updated in December 2009, however, the associated screen capture demonstrations and specific directions have not been updated and are based on the current versions of software at that time.
The Adobe Corporation introduced the Acrobat product in 1993 as a means of providing a universal document format that would allow various files to be read on any computer, using any operating system[Footnote 1]. At the time, there were several operating systems in use. Add to this a number of competing word processors and desktop publishing applications and the introduction of a universal format made a lot of sense.
Over the years as two or three operating systems and an equal number of office applications began to dominate the market, the need for a universal format diminished but did not disappeared completely. Meanwhile the folks at Adobe continued to upgrade their product and developed a niche by providing a mechanism that would allow documents to be shared in a "secure"format, meaning, the text could not be modified by the reader. Some businesses and organizations also liked the way rich text desktop publishing and print content could be shared in electronic format.
However, by the late 1990s the death of Acrobat was announced by many in the industry. At about the same time Acrobat was introduced, HTML was being developed and quickly emerged as the universal, non-proprietary standard for document sharing. HTML offered the ability to create and easily share colorful rich text documents complete with images in a format that could easily be viewed on any computer. But despite the doom-and-gloom assertions, and HTML’s continued growth, the use of Adobe Acrobat and other products that produce PDF files has flourished.
In the early years, the Portable Document Format (PDF) was simply a graphic image of a finished document. Using the free Adobe Acrobat Reader application, it was nearly impossible to edit or modify a PDF file once it was created. Indeed, as noted above, this was considered a desirable feature.
The PDF has come a long way since then, and while one is still required to use a special reader to view the file, there are now a number of applications[Footnote 2] that will save and read a document in PDF. Indeed the latest version of Microsoft Office has a free plug-in that will convert any Office document into a PDF file.
The use of Adobe Acrobat PDF files has historically been opposed by accessibility experts. For many years, the standard screen reading software programs were not able to read PDFs and when they could, the content of the document was often so scattered and disorganized it was unintelligible.
With the advent of Section 508 of the Vocational Rehabilitation Act, Adobe recognized that it needed to update Acrobat and make it produce accessible documents if it wanted to continue to sell its product to the federal government. Ironically, it was the federal Internal Revenue Service that first freely distributed the Acrobat Reader (Pfiffner, 2003).
Within the past few years, Adobe has made dramatic progress in making the Acrobat product capable of producing fully accessible documents. That said, one should still be cautious as there are several conditions that must be met to ensure that users with disabilities will be able to read PDF files. First, the PDF document must be created from a document containing actual content. This means that the PDF cannot be made from a scanned image. Second, one must use Adobe Acrobat Professional (version 8 or newer) to scan and test the document for accessibility. Third, the person reading the PDF document should be using the latest version of Adobe Acrobat Reader. And last, the user should have installed on their computer the current version of their screen reading software.
The most efficient way to create an accessible PDF file is to use Adobe Acrobat Professional and make sure you test the document with the Accessibility Checker that is built into the application. This wizard will scan the PDF file and identify accessibility issues in the document. It will also provide a detailed report on what the issues are and give specific directions for fixing the issues. In most cases Acrobat Professional also contains the tools needed to "fix" accessibility issues and modify the PDF document without needing access to the original document from which the PDF was made.
Although you can create new documents with Acrobat Professional, ideally documents are written and designed in other applications and either "imported" (File > Create PDF > From File>) or saved in PDF from the other application and then tested with Accessibility Checker.
In testing a multitude of "imported" word processed documents, three common errors emerged. They were: 1) the absence of the document language, 2) the absence of appropriate alternative text descriptions for images, and 3) numerous situations where the reading order of content was judged to be out of sequence. While all three of these issues can be fixed with Acrobat Professional, some may be avoided if the original document is designed correctly. General office documents of all types should be constructed using the accessibility modifications we have detailed in the previous articles in this series. While doing so will often result in converted files being fully accessible PDF files, in our testing, accessibility errors were still found more often than not.
Fixing PDFs with Acrobat Professional can range from the very simple to fairly complex. Adding document language information and alternative text for images can be accomplished quickly by following a few simple steps (see below). However, fixing a PDF where the content is not in the correct sequence can be fairly time consuming. The process, called "tagging the document," involves identifying sections of the text, including heading, footnotes, images and other features and tagging them with the appropriate content code. While Acrobat Professional will do a pretty good job in identifying these sections automatically, occasional one tagged section will be in the wrong sequential order. If the PDF were shared with a person using a screen reader, the user would likely hear the content in the wrong order and easily become confused.
To test this experience in preparation for this article, we used the Read Out Loud[Footnote 3] feature of the Adobe Acrobat Reader to mimic what a person using a screen reader might hear. We tested a PDF document that had been identified by the Accessibility Checker as one which might have some sequencing problems. In this particular document, a legal brief, the author had made rather extensive use of footnotes. When the Read Out Loud application began to "read"the document it read the footnote markers as numbers (which contextually made no sense) and when it got to the bottom of the page, the application read the footnoted content as thought it was part of the main content of the document. In this example, it is fairly clear that simply converting a document of this type into PDF without the significant modifications and re-tagging, rendered the final PDF as significantly inaccessible to persons using screen readers.
The issue of content being out of sequence is particularly a problem with documents created with desktop publishing applications such as MS Publisher. As these applications allow designers to place the content in any location on the page, their conversion to PDFs should be avoided. It should however be noted that the desktop publishing application Adobe InDesign (and formerly PageMaker) does contain an export feature that will generally convert the document into an accessible, correctly tagged PDF file. However, as in all cases with PDF, the document should always be tested for accessibility before being distributed.
The step-by-step directions and detailed video tutorials for using the Accessibility Checker and all of the accessibility features of Acrobat Professional are available on the Adobe Acrobat Accessibility training resources website http://www.adobe.com/enterprise/accessibility/training.html
Here are directions for remediating the two most common problems:
Adding Document Language to Entire Document
Choose File> Properties> Advanced tab and click on the Language field (the last dropdown input box at the bottom of the screen) and choose the language for the document from the choices available. Typically we will choose "English US."Note: sections of the document that are in a different language can also be identified by choosing the section from within the Tag tree and then following the directions above.
Adding Alternate Text
To add alternate text to an image,
To add alternate text to tags in the tags panel, select the tag, choose Options> Properties, click on the Tag tab, and fill in the alternate text field.
As noted, there are a number of free and low cost applications that will convert word processor (and other format) files into PDF including a free plug-in for MS Office 2007 (see http://www.microsoft.com/downloads/details.aspx?FamilyId=F1FC413C-6D89-4F15-991B-63B07BA5F2E5&displaylang=en)
To ensure that your final PDF is accessible, the original document needs to incorporate all of the accessibility modifications which we have detailed in previous articles in this series. For example, all images inserted into the original document must have alternative text descriptions added. The document language is generally set in the default settings of the office application and need only be changed when a section of the document has a language change. In our testing, we discovered that less than half of the MS-Word documents that were saved or imported into PDF format had retained the document language information.
Word processor documents that have used the correct forms of headings will generally convert correctly. We tested this with the MS Office plug-in, the Adobe Acrobat plug-in for Office and in Open Office documents in both Ubuntu and Windows. Most - but NOT all - of the files converted into accessible PDFs even when they were correctly designed in the original application. Therefore it is essential to check your PDF documents with the Accessibility Checker in Acrobat Professional especially if you intend to post your PDFs on a website or make them available to the general public.
While there has been some significant effort by Adobe to improve the accessibility of Acrobat PDF output, we caution readers that it is essential to test all of their PDF documents before posting to the general public. Given the fact that users may still not have all of the resources at their end to render PDFs accurately, we must therefore still advocate that when important content is shared with the general public multiple formats be offered. And, we generally believe that documents produced in accessible, standards-based HTML format are the best for ensuring accessibility.
Pfiffner, P. (2003). Inside the publishing revolution: The Adobe story. Berkeley, CA: Adobe Press.
[Footnote 1] For a more complete history of the Adobe Acrobat product please see http://www.planetpdf.com/mainpage.asp?webpageid=2497 and http://en.wikipedia.org/wiki/Adobe_Acrobat
[Footnote 2] The Adobe Acrobat Reader is still the most commonly used reader application. See a list of alternative readers on Wikipedia http://en.wikipedia.org/wiki/List_of_PDF_software
[Footnote 3] For more information about Read Out Loud and how to use it, see the WebAIM article Accessibility Features in Acrobat Reader http://www.webaim.org/resources/reader/#outloud
Maine CITE provides additional resources that can help you with your goal of creating accessible documents. http://www.mainecite.org/awd/accdocs.html
John Brandt is a web designer and consultant who works with the Maine CITE Program in the area of accessibility and universal design. He may be reached at firstname.lastname@example.org
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