The appropriate use of PDF files is a hotly debated topic, both inside and outside the field of Web accessibility. Some people would argue that there is no place for PDF files, while others suggest that appropriately prepared PDF's are basically as accessible as HTML. We think the truth lies somewhere in-between. PDF files do have their place-displaying documents that print exactly as the author intends.
In order for a PDF to be truly accessible two conditions must be met:
- The author must create a well structured, correctly tagged, PDF.
- The reader must be able to correctly configure his or her accessibility preferences in Adobe Reader.
Both of these conditions will be discussed in this tutorial.
Remembering the Needs of All Users
As with HTML, you need to know what kinds of issues people with disabilities might encounter when reading PDF files. When people talk about the accessibility of Adobe Acrobat, or PDF files, they are usually referring to the accessibility of Acrobat to screen readers, but screen reader users are not the only people who should be considered when creating accessible PDF files. It is important to remember that not everyone with a disability is blind. You should also consider the needs of individuals with motor disabilities, hearing disabilities, cognitive disabilities or low vision. Let's look at some general guidelines for making PDF files accessible to people with other types of disabilities.
Don't make hot spots too small. Of course, the phrase "too small" is relative, and it is true that people can enlarge the document, thus enlarging the hot spots within the document, but use good judgment here. The smaller the link, the more difficult it will be for someone with limited fine muscle control to click on the link.
Provide transcripts for multimedia. If you embed multimedia objects with sound in your PDF documents, you will exclude both the deaf and the deaf-blind if you do not provide a transcript.
Provide synchronized captions for video. People who are deaf need this if the video does not make sense when the sound is turned off.
Use clear and simple language. In other words, write well. The better you write, the better you will be understood by everyone, not just those with cognitive disabilities.
Make the document accessible to screen readers. Not all people with cognitive disabilities use or benefit from hearing the content read to them, but some do. In order for the content to be read out loud, it must be accessible to screen readers.
Ensure that there is enough contrast in the PDF document.
Ensure that any information conveyed with color is conveyed equally well when color is not available. You may want to use a textual cue in addition to the color in order to convey the information.
Blindness and screen reader accessibility
Before the release of Acrobat 5.0, PDF files were not accessible to screen readers in any meaningful way. Now it is possible to expose the text in PDF files to screen readers, but much like HTML, PDF files must be created with accessibility in mind. Otherwise, the files will be nearly as inaccessible as before Acrobat 5.0 came about. The bad news is that it usually takes more work to make PDF files accessible than it does to make HTML files accessible. Still, it can be done.
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