Notes: Accessibility of PDF documents

PDFs are not accessible by default

Without some careful thought and attention on the part of the creator, PDF documents do not meet the most basic accessibility criteria; they have no 'marked-up' structure that would be useful to assistive technologies, and they can't be read by most screen reading programs.

The latest version of Acrobat Reader (Version 5) - introducing improvements in both of these areas; PDF documents are now directly accessible to a limited number of screen reading applications, and the content can be tagged in a similar way to HTML pages. Adobe must be applauded for their efforts to address accessibility issues, however, because these changes currently only benefit a limited number of users, the best approach is to provide the information contained within PDF documents in an alternative format. Ideally this means providing the same information as a Web page or as a set of Web pages.

Converting PDF documents to HTML or text

Adobe provide the services listed below to converted PDF documents to HTML or text. These services work best with PDF document created using the most recent version of Adobe Acrobat

PDF to HTML or text

By typing the URL of the PDF document into the form at http://access.adobe.com/simple_form.html the document will be converted into HTML and the results displayed in the users browser.

PDF to HTML or text via e-mail

The URL of a PDF document can be submitted via e-mail at http://access.adobe.com/access_email.html. The HTML or text will be return as an attachment.

A PDF document can also be sent as an attachment - and will be returned as text in the body of the mail message. More information from http://access.adobe.com/access_email.html

Converting PDF to text using the Acrobat Access plug-in

Windows users have access to the Acrobat Access plug-in - which can be used to convert PDF documents to plain text. The plugin works with version Acrobat 4 onwards. More information about the plugin can be found at: http://access.adobe.com/access_plugin.html

Service from Trace Research Center

Trace Research Center also provide the following useful services:

PDF to text via e-mail:

You can either mail the URL of the Adobe PDF or attach the Adobe PDF document itself to your email message and send it to pdf2txt@sun.trace.wisc.edu (for plain text) or to pdf2html@sun.trace.wisc.edu (for HTML). The convertor will mail back the translation of the PDF file.

Using Google to search and convert PDFs

The following tip was sent to me by Alexandra Enders:

"Google has a built in text extractor -- if I am searching on google, I just open the html option instead of pdf -- if the document can be extracted, google always lists html as a option to the pdf. When I find a pdf document I usually just save the url of the pdf file, put it into the google search line, and let google extract to an html file -- seems easier and quicker than going to adobe. I always feel like I am cheating, but it works."

Thanks Alexandra.

Accessibility features of Acrobat Reader 5

Acrobat reader 5 provides a number of accessibility enhancements:

• Selected screen readers (currently only JAWS and Window Eyes) can now be used to read PDF documents.
• Document navigation is available via the Keyboard.
• Contrast can be adjusted.
• When working with tagged (accessible ) PDF files, text can be resized.

Creators of Adobe 5 PDF documents can now:

• Add tags to elements of PDF documents
• Check the accessibility of documents as they are being created.
• Existing Adobe PDF files can be converted to tagged Adobe PDF.
• Tagged Adobe PDF files can be exported to RTF (Rich Text Format) or XML, HTML, or TXT.

The ability of authors to add 'HTML-like' tags to PDF documents is a significant step towards making those documents accessible. However, there is little evidence that people are adopting this new technique. Information about adding tags to PDF documents can be found at http://access.adobe.com/booklet.html and in the (PDF only) document at http://www.adobe.com/products/acrobat/pdfs/CreateAccessibleAdvanced.pdf.

WebAIM rightly point out that most of the above techniques are related to making PDF documents accessible to blind or visually impaired people using screen readers. But these techniques, in addition to using clear language will also help people with cognitive impairments.

Making PDFs more accessible for people with hearing impairments

• if you embed video within your PDFs provide synchronized video.
• Provide a transcript of if you use multimedia elements containing sound.

Other things worth remembering.

When plugins are required for access to content, a link to the appropriate plugin page should be provided.

• Acrobat Reader download page (http://www.adobe.com/products/acrobat/readstep.html).
• The accessible version of the download page (http://www.adobe.com/products/acrobat/alternate.html).

Encrypted PDF documents for security purposes can cause problems; some assistive technologies can be locked out, even though the document is visible on the screen. The National Center on Accessible Information Technology in Education note that 40-bit encryption is inaccessible; whereas 128-bit is accessible.

In summary:

• Ideally provide the same information in an alternative format - preferably HTML.
• Provide a link to the download page for the PDF plugin.
• Provide a link to the Adobe Access page at http://access.adobe.com/ with the information that the PDF can be converted to HTML or text.
• Use the latest version of the software used to create PDFs and use the new accessibility techniques developed by Adobe when creating your documents.

Note: Adobe Acrobat has been updated to version 6 and includes new accessibility features - check the Adobe website for more information.

Jim Byrne August 2002.

Contributed by Jim Byrne
Updated Monday 25 Aug 2003

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