PDF Accessibility

Using the Internet has become so commonplace, that we do not even think about what it demands from us as interactive users, let alone PDF users. There are a large number of PDF documents being used on the Internet daily. From instruction manuals to working documents, the proliferation of the PDF format implies, if not insists, that any person should have access to them.

Accessibility For Whom?

It is taken for granted that all computer users can manipulate and manage the equipment used to access digital content. However, this is not always the case. Users suffering from colour blindness or weak visual perception, for instance, cannot easily distinguish the details in complex digital images. Those with hearing impairments cannot full use of media with audio elements. Physical disabilities, in the form of bone fractures, missing limbs or chronic inflammation of the joints, prevent accessing content through the use of a keyboard or mouse. The aim of accessibility is to provide for those users with disabilities alternative methods of interacting with digital content.

Accessibility Regulations

The issue of PDF accessibility itself falls under the same regulations governing electronic information. The widely adopted accessibility standard in most countries is the W3C’s Web Content Accessibility Guidelines (WCAG 1.0). It consists of 14 guidelines, with each guideline containing 3 priority checkpoints which must be met when creating electronic content.

In the U.S. there is the Rehabilitation Act, which was amended with Section 508 and fully implemented in 2001 which is also widely followed. The section states that all US federal agencies must ensure that all digital content and information is accessible to people with disabilities. Both are separate and individual regulating bodies, yet are very similar because Section 508 is based on WCAG priority one checkpoints.

Also remember that PDF is a de facto standard, which means that there are no standards written specifically for the format. However, a PDF/UA standard (PDF for Universal Access), is in early discussion. It is being focused upon the accessibility of PDF files and will comply with the PDF authoring guidelines of Section 508.

Authoring Accessible PDFs

Authoring a PDF that is accessible means creating a PDF that is properly structured. As it is with XML, the separation between appearance and content is important. This is because validated tags applied to a PDF provides a way for assistive devices to interpret and render the PDF data.

The proper structuring of a PDF file involves a number of things. It includes adding alternative text for image descriptions and hypertext link information. It also involves embedding keyboard shortcuts as navigational alternatives. Structuring a PDF also means that the structural reflow must be accurate so that content displays properly on device monitors of different sizes. Validating the logical order and reading order of page content is also necessary to ensure a coherent rendition of the PDF content.

Alternatives to creating accessible PDFs exist as well. One is to create the document in HTML. Another is to provide a version in textual format, such as RTF or a Word document. Or, if you have an untagged PDF, you can convert it into a tagged one for accessibility. However, scanned documents cannot create a tagged PDF and, consequently, tags and reflowing must be created manually or through OCR techniques.

Assistive Technology And Software

With a tagged PDF, devices such as screen readers (Jaws, Window Eyes), can read the content of PDFs out loud for those with visual impairments. With embedded keyboard shortcuts, the effort and precision needed for handling a mouse is minimized. When accurately structured, reflowed text displays on touch screens, eliminating the obstacle of a keyboard. Fortunately, in the last few years, PDF creation software has rapidly developed to accommodate these devices.

In particular, since Acrobat 5 (2001), Adobe has been adding accessibility functionality into its software. For instance, Acrobat 6 and later can automatically (or manually) generate tags for reading order. In addition, Adobe Reader is equipped to act like a simple assistive device with the functionality to read PDF text out loud, to switch to full screen and zoom modes, and to check for a document’s level of accessibility.

Manipulating and adding simple alternatives to electronic documents is just one step towards creating a document readily available to all. PDF accessibility has progressed since 2001 and it can only continue to do so as the use of the accessible PDF format increases.