PDF Accessibility
PDF is a convenient way to put an existing content in a document on a Website. However the rapid growth in the use of PDFs on Websites has led to increasing concerns about accessibility, particularly for the users of screen reading technology, which converts text into synthetic speech. We need to make PDF files on the web accessible for the same reasons we make other web content accessible.
Before the release of Acrobat 5 in 2001, information presented in PDFs was generally considered inaccessible. However, the release of Acrobat 5 was a significant step in improving the accessibility of PDF documents. Version 5 and later allowed content to be tagged in a similar way to HTML documents. We can add XML-like tags to give structure to a PDF. What makes PDFs robust and accessible is the structure. A PDF is probably accessible if it is tagged. Screen readers had to be upgraded to understand these PDF tags. Whereas mere presence of tags does not guarantee accessibility, since they might have been wrongly used, the absence of tags definitely renders the PDF inaccessible.
The World Wide Web Consortium (W3C) does not recognize PDF as a standard format since it requires the Acrobat browser plug-in to access the information contained in the document. Although recent advances have made it possible to create a PDF document that can be accessed by a greater number of people, the Web Content Accessibility Guidelines (WCAG) of the W3C do not yet consider PDF as fully accessible.
In situations where providing accessible PDFs is not possible, some alternative should be provided for users who are unable to access the PDF but would still want the information it contains. The ideal accessible alternative for content provided in a PDF file is an equivalent HTML page that is both valid and accessible.
PDF accessibility is not as straightforward as HTML accessibility. The use of PDFs still causes accessibility problems for some Web users. However, in the next few years, the extent of this problem is likely to reduce as more accessible PDFs are produced and an increasing number of assistive technology users upgrade their devices.
Nishtha Srivastava (nishtha_srivastava@infosys.com)
Tarun Prakash Sharma (TarunPrakash_S@infosys.com)
Web 2.0 Research Lab, SETLabs.
