PDFs and Accessibility (2004)
As the Web evolves, new software and applications for use on Websites are being developed. Many of these new applications are proprietary products that don’t use standard features recognised by the World Wide Web Consortium (W3C). The use of non-standard formats can cause significant accessibility problems for some people.
Use W3C technologies (according to specification) and follow accessibility guidelines. Where it is not possible to use a W3C technology, or doing so results in material that does not transform gracefully, provide an alternative version of the content that is accessible.
Many non-W3C formats (e.g., PDF, Shockwave, etc) require viewing with either plug-ins or stand-alone applications. Often, these formats cannot be viewed or navigated with standard user agents (including assistive technologies).”
Web Content Accessibility Guideline 11.
This Accessibility Guideline is probably one of the most contentious and difficult to interpret. In many cases the potential accessibility of a non-W3C application that requires specialist software is determined by three factors:
- The inherent accessibility of the application, or application version.
- The availability of user software (readers) to render the application, and the technological capacity needed for that software.
- The ability of current assistive technologies to access content generated by the application and rendered by the user software.
Portable Document Format
PDF has been developed by Adobe for the distribution of electronic documents in a format that retains the exact look of the source material. PDF files can be created by scanning a printed document or by using Adobe Acrobat (writer) to convert an electronic document, which has been produced by another application such as Microsoft Word, Pagemaker or QuarkXPress, into the Portable Document Format.
Adobe also provides Acrobat Reader, free software that allows PDF files to be viewed and printed using a variety of hardware and operating system platforms. The ability of PDF files to look exactly the same regardless of the system used to access them has lead to the increasing use of PDFs on Websites in recent years. The name of the PDF reader was changed to Adobe Reader with the release of Version 6.
PDF is a quick and convenient way to put an existing document on a Website. PDFs are used on Websites for many reasons, some of the most common today are:
- Brochures and information fact sheets.
- Large public documents that contain charts and images, such as annual reports.
- Documents that exist in hard copy but have a very short life, eg press releases.
- Fax-back order/request forms for the user to print out.
- Contracts and agreements for the user to print.
- Secure password-protected documents.
The rapid growth in the use of PDFs on Websites has lead to increasing concerns about accessibility, particularly for the users of screen reading technology, which converts text into synthetic speech or electronic Braille. Before the release of Acrobat 5 in 2001, information presented in PDFs was generally considered inaccessible, although a plugin was available for Acrobat 4 that did provide some access to PDF documents.
PDF is not recognised by the W3C as a standard format. The use of PDF content on Websites is covered, in part, by a number of Web Content Accessibility Guideline checkpoints including:
“Provide a text equivalent for every non-text element. This includes images, graphical representations of text …”
WCAG Checkpoint 1.1
“Ensure that pages are accessible even when newer technologies are not supported or are turned off.”
WCA Guideline 6
The lack of accessibility of PDF documents exposes Websites proprietors to the risk of legal action under laws in many countries that protect people against discrimination. In Australia, the Disability Discrimination Act requires the providers of goods and services through the web to ensure equal access for people with a disability.
Adobe sought to address this problem in three ways.
- Releasing Acrobat 5 software in 2001. With the release of an enhanced update, Acrobat 5.0.5 in January the following year, it was now possible to produce some PDF documents that were accessible to the users of some assistive technologies.
- Converting a PDF document on a Website to HTML or text via a free online tool. Not all PDF documents can be successfully converted using this tool. http://www.adobe.com/products/acrobat/access_simple_form.html
- Providing a conversion service for PDF documents submitted via email. http://www.adobe.com/products/acrobat/access_email.html
An important feature of Adobe Acrobat 5 was the support it offered screen readers via Microsoft Active Accessibility (MSAA) technology for Windows. Acrobat 5.0.5 provided greater integration with the Microsoft Office suite of programs and version 5 and later allowed content to be tagged in a similar way to HTML documents. The Acrobat 5 Reader also offered the potential for users to navigate a PDF via the keyboard and fill in and submit PDF forms online.
PDF Tags are used to define the structure of a document. They can be used to ensure the reading order for content on the page and include the required paragraph attributes needed to reflow text correctly for different screen sizes and devices. Tags also provide a standardized approach to describing text characters, regardless of font, so that a screen reader can read all characters and words correctly.
The release of Acrobat 5 was a significant step in improving the accessibility of PDF documents however; there are still some significant problems, including the lack of PDF accessibility support in non-windows operating systems.
In 2003, Adobe released the substantially upgraded Acrobat 6 promising enhanced accessibility.
“Acrobat 6 and the free Adobe Reader 6 enable users with disabilities to access, read and use Adobe PDF documents and forms – across multiple languages, including Japanese – more easily. And the improved tools for generating, reviewing, and enhancing Adobe PDF files found in the Acrobat family make it easier for authors to create and distribute electronic content that is optimised for accessibility.
Adobe Acrobat 6.0 and Accessibility.
Adobe offers two versions of Acrobat 6: Professional and Standard. Both versions contain greatly improved accessibility features, however some of the most advanced, including the ability to create and optimise accessible PDF forms, are only included in Acrobat 6 Professional.
Acrobat 6 and Reader 6 allow the text in a PDF file to be synthesized into speech using capabilities available in standard Windows operating systems and Mac OS X. This facility only works with basic PDF text files and full access to more complex PDFs is still only available to Microsoft Windows users. The use of Microsoft Active Accessibility (MSAA) means that Acrobat 6 for Windows will also integrate with a range of assistive technologies including recent versions of Braille devices and the two most widely used screen readers, JAWS (from Freedom Scientific) and Window Eyes (from GW Micro).
In some circumstances Website users may want to save a PDF file as a text file. Adobe advises, “Both Acrobat and Reader let a user save Adobe PDF content, including alternative text for graphics, as ASCII text files. Acrobat also offers the option to export text to RTF, XML, HTML and Word (Doc).”
Acrobat 6 contains a facility for automatically converting existing Adobe PDF documents into tagged PDF files that approximate the structure and reading order of the original document. In most cases, tagged files will translate better with a screen reader than untagged files. If the source document however, is not very simple the tagging results may not be reliable and should be checked to ensure the process was performed correctly.
The advances in Acrobat 6 and Reader 6 mean that is now theoretically possible for authors to create quite complex documents including forms in PDF that are accessible to many assistive technology users. However this is only possible if the authors create the documents carefully and with the aim of providing for enhanced accessibility.
Creating Accessible PDFs
To guarantee that a PDF document will be accessible it has to be prepared in strict accordance with the guidelines provided by Adobe and written using the Adobe Acrobat (Writer) version 5 or later.
Adobe provide a 30 page downloadable booklet, “How to Create Accessible Adobe PDF Files”, which describes in detail what is required to create a PDF with enhanced accessibility. The booklet is available at: http://www.adobe.com/products/acrobat/access_booklet.html
Some of the main requirements for preparing accessible PDFs are briefly outlined below:
- When a paper document is scanned to create a PDF the resulting file is a PDF Image Only file – that is, bitmap pictures of the pages. Although the page can be viewed with Acrobat, the content cannot be recognised by screen readers and so is not accessible. To make a PDF Image Only file accessible the document needs to be “captured” using Adobe Acrobat Capture 3 or the paper capture facility provided with Acrobat 6 and a tagged PDF file created: http://www.adobe.com/products/acrcapture/main.html
- Text files such as documents generated by word processing or desktop publishing software are the most suitable for making accessible PDFs.
- Accessible documents must be in the tagged PDF format and this is easiest to do with documents generated with Microsoft Office 2000 or higher. If you are not using Microsoft Office it may be necessary to download the ‘Make Accessible Plug-in’ from the Adobe website for Acrobat 5, use the automatic tagging facility in Acrobat 6 and perhaps create some of the tags by hand.
- Word 2000 lets you create tagged Adobe PDF files. However the Word document must be well marked up and use styles to format text such as headings and paragraphs. That is, not by highlighting a piece of text and using the font and bold options to change its look.
- Also, use styles to provide structure to the document. Use the “spacing before” and “spacing after” paragraph properties rather than the enter (return) key to add space between paragraphs.
- Use the Column command in Word to create columns and the Insert Table or Draw Table tool to create tables.
- Add alternative text to all images. In Word you can add descriptive text via the Web tab of the pictures Properties dialogue box within the Format menu.
- All the parts of a composite image should be grouped using the Group command.
- Use the Acrobat Tags palette and the forms tool to create accessible electronic PDF forms.
Untagged PDF files such as those created with Acrobat 4 (and earlier) can be converted into accessible (tagged) PDF with the ‘Make Accessible’ plug-in developed for Acrobat 5 or from within Acrobat 6. Tagged files created in this way should always be checked with a screen reader for reading order and content sense as well as accessibility.
Information about the ‘Make Accessible’ plug-in and download are available at: http://www.adobe.com/support/downloads/detail.jsp?hexID=88de
When information is provided via a PDF, the link to the document should include a short summary of the information it contains, an indication of the document size in KB file size and page number and an estimated download time at 56 kbps.
Is PDF Accessibility Still An Issue?
The short answer is YES
The commitment Adobe has made to improving the accessibility of PDFs has been widely recognised by disability groups and accessibility advocates and has directly benefited many users of assistive technologies.
The general opinion of the accessibility community world wide however, is that the use of PDFs on Websites still presents a significant barrier for people with disabilities, in particular for sight impaired Web users who rely on screen reader technology.
In Australia, the Human Rights and Equal Opportunity Commission has indicated that the use of PDF documents on Websites is still a significant accessibility issue.
The use of PDF documents on Websites raise five possible areas of concern:
- Legacy documents. PDF documents generated with early versions of Acrobat that are not accessible and have not been converted into more accessible PDFs. In cases where these legacy documents are no longer relevant the simplest solution to this problem is their removal from the site.
- Scanned documents. PDF Image Only files created by scanning an existing printed document are often very hard to make accessible.
- Unused accessibility enhancements. The enhanced accessibility of PDFs generated with recent versions of Adobe Acrobat is only achievable when the accessibility features are used appropriately.
- Lack of accessible PDF support by all operating systems. Currently full accessibility support is only available for 32-bit Windows environments.
- Variable assistive technology support for PDFs. Accessibility of PDFs by assistive technologies depends on the manufacturers of those technologies incorporating PDF support into their products. Several manufacturers have done this with recent versions of their products, but for the many users of earlier versions of the technology PDFs will remain inaccessible.
In 2004, the use of PDFs can still cause accessibility problems for some Web users. However over the next few years, the extent of this problem is likely to diminish as older PDFs are removed from Websites, more accessible PDFs are produced and an increasing number of assistive technology users upgrade their devices.
Alternatives for PDF Content
PDFs are a non-standard W3C format that requires the Acrobat browser plug-in to access the information contained in the document. Even though recent advances mean that it is now possible to create a PDF document that can be accessed by a greater number of people, PDFs should not be considered accessible in terms of the W3C Web Content Accessibility Guidelines.
Accessibility enhanced PDFs still can’t be accessed by a range of web users including:
- People who are unable to install the Acrobat reader software.
- People with slow connection speeds who are not willing to install Acrobat.
- People who use operating systems and browsers that do not support PDF.
- People with assistive technology versions that do not support PDF.
“If after best efforts, you cannot create an accessible page, provide a link to an alternative page that uses W3C technologies, is accessible, has equivalent information (or functionality), and is updated as often as the inaccessible (original) page.”
WCAG Checkpoint 11.4
In most cases, the text information contained in a PDF was originally generated in some other format, commonly MS Word or Excel. This original source material can be used (and where necessary modified) to create an equivalent alternative for the information provided in the PDF
The ideal accessible alternative for content provided in a PDF file is an equivalent HTML page that is both valid and accessible.
Where a HTML alternative is not possible, the information should be provided in text format (RTF) and failing this as a Word or Excel document. In these cases, descriptions should be provided for information conveyed via charts, graphs and images.
Where it is not possible to provide an accessible online alternative for some content, for example a complex form or detailed geographic map, contact details such as a phone number and/or email address should be provided so that someone who is unable to access the PDF can still obtain the information in contains.
References and Additional Information
Maximum Accessibility: Making Your Web Site More Usable for Everyone. John Slatin and Sharron Rush, 2003. Addison-Wesley, Boston.
- Adobe Acrobat: Solutions for Accessibility. Adobe
- How to Create Accessible Adobe PDF Files. Adobe
- Is PDF Accessible? AccessIT (National Center on Accessible Information Technology in Education, University of Washington)
- Adobe Acrobat Accessibility Techniques. WebAim
- Quick reference for Adobe Acrobat 5.0 and 6.0. University of Wisconsin-Madison
- Accessibility of PDF Documents. Jim Byrne, MCU Accessible web design consultancy.
- PDF and Public Documents: A White Paper, Janina Sajka and Joe Roeder. American Foundation for the Blind
- World Wide Web Access: Disability Discrimination Act Advisory Notes. Australian Human Rights and Equal Opportunity Commission (HREOC)