PDFs: Handle with care
- Article 16 of 26
- M-iD, March 2005
There is more to Adobe Acrobat PDFs than meets the eye, especially if an organisation wants its documents to be accessible for disabled users.
Every web site is a motley collection of file types: HTML text; GIF, PNG or JPG images; and, increasingly often, Adobe Portable Document Format (PDF) files for downloading and printing documents.
PDF has many advantages for organisations that want to distribute documents over the Internet: they often have small file sizes relative to the original documents; anyone can view them on just about any platform; and they can mimic virtually any document, even if the end viewer does not have access to the same fonts or programs as the originator of the document.
But are they suitable for an organisation that wants to remain compliant with accessibility legislation?
The Disability Discrimination Act 1995 (DDA) dictates that web-based services, including PDF files, must be accessible to disabled users. So any organisation that provides PDF files on its web site either has to provide an alternative way to access the information in the files for users who are unable to view PDFs, such as a free phone information line, or they have to make their PDF files compatible with accessibility technology. This is actually harder than many at first suspect.
“Basically, no one understands it,” says Paul Randall, senior consultant at consultancy Mekon. “Technologies such as HTML are well understood by people wanting to make web sites accessible under the DDA. But the big gap in knowledge is the PDF. It's almost a mystery to people.”
Typically, most PDFs are generated using Adobe Acrobat plug-ins for software such as Word, InDesign, QuarkXPress and Photoshop or using scanners with optical character recognition (OCR) software (any scanned document that is not put through OCR software will be totally inaccessible since screen readers will not be able to read out the text).
Most organisations will then simply provide that PDF to end users without working on it any further. But Acrobat has many built-in functions that can make it more accessible in a short space of time. “You can do a simple 'Save As' in Acrobat and that will create a 'fast web view' by default. We put 50 megabyte files on the web but you would not know because you're only downloading one page at a time which is a just a few kilobytes,” adds Randall.
Acrobat's batch processing capability means that a whole directory of PDFs can be re-saved automatically with fast web views. Acrobat can also instruct screen readers how to read documents out loud - a screen reader will often read headlines in a different tone from body text - if it can determine the structure of the document.
If the document does not have a stored structure, Acrobat can intelligently work through the document, calculating which parts are headlines through changes in font size and weight. But Word's Acrobat plug-in is able to provide this information to Acrobat automatically, provided the original document has been set up correctly.
“If you set up styles in Word, with headings, bullets, numbered lists, provide ALT text for images and so on then the PDF will have that accessibility information. If you write a flat Word document, everything stays body text,” says Randall. “One of the great problems with Word is that there's very little training: most people pick it up as they go along and don't know how to do provide this extra information.”
By providing Word templates with embedded styles and training on how to use these features, organisations can ensure that many of their PDFs have at least a minimum level of accessibility.
To create a fully accessible PDF with summary data for tables so that screen readers can provide brief synopses of tables rather than reading them all out, can take a day for someone with a good understanding of XML, suggests Randall. This puts it out of reach of many organisations, he concedes.
But, he adds, “a few little things can make it a bit better. Just be reasonable in what you do.”
Mekon's recommendations for PDF accessibility
- Document colours: high-contrast colours should be chosen for background and text to enhance readability;
- Bookmark text size: this feature, which allows the size and wrapping of bookmarks to be controlled, should be set to large to increase readability;
- Automatic scrolling: setting slow automatic text scrolling means readers will not need to use a mouse to scroll through the document;
- Read out loud: activating this feature will allow a section, page or entire document to be read out loud by a screen reader;
- Reflow: this feature provides readers with a magnified version of the document which they can read without needing to use a mouse;
- Multimedia: switching on features such as subtitles will help to increase accessibility;
- Create articles: creating articles will allow screen readers to link paragraphs of text which carry over on to different pages so that the user has access to the full article.