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An introduction to PDF Accessibility

By Jon Gooday, AbilityNet

This article explains the key accessibility issues for people with disabilities with reading PDFs, and explores the inbuilt accessibility tools built into Adobe Acrobat. It also gives a quick tutorial on converting a Word document to an accessible PDF.

Introduction

The early versions of Adobe PDF were completely inaccessible. Fortunately this began to change with Acrobat 5, when real text was introduced to offer an accessible alternative to images of text. Another key development was the introduction of ‘tags’ to PDFs, a similar concept to tags in Html, to add extra non visual information to documents that can be understood by adaptive technology such as screen readers used by blind/partially sighted people.

Although PDF tags cannot be manipulated as easily as html tags, they make the content more accessible if used correctly. With each version of Adobe Acrobat, PDF accessibility has increased and it is becoming easier to create accessible ‘tagged’ PDF files.

When should I use PDF?

When you should use PDFs as opposed to an another format such as a Word document or HTML is an important question - the appropriate use of PDF files is a hotly debated topic, both inside and outside the field of Web accessibility. Ideally PDFs should be used for documents that need to be printed out exactly as the author intends – for example newsletters, flyers or annual reports.

Issues people with Disabilities have with PDFs

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 thinking about 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.

In addition to those with severe/moderate vision impairment you need to consider the needs of people with motor disabilities, hearing disabilities, cognitive disabilities or low vision / colour blindness.

What follows are some general guidelines for making PDF files accessible to these broad categories of disabilities.

Low vision/ Colour blindness

You need to ensure that there is enough contrast in the PDF document between text and background – there are plenty of tools to help you check this – see the reference section at the end.

Also be careful about using colour only when referring to something in the document like a graph or chart – don’t say ‘look at the red line on the graph’ for example – be more specific because people with colour blindness cannot differentiate certain colours.

Motor disabilities

Don't make hot spots around links too small – you can easily change link settings to change the hot spot areas. The key point to be aware of is that the smaller the link, the more difficult it will be for someone with limited fine muscle/motor control to click on it.

Hearing disabilities

You can add sound and movie clips to PDFs if you have Adobe Acrobat Professional, 6.0 or later.  If you want to do this make sure you provide transcripts for any sound file such as wav.

Also if you embed movie files (such as QuickTime, Flash Player, Windows® Media Player etc) provide synchronized captions for the video, alternatively provide a transcript.

Cognitive disabilities

The number one rule is use clear and simple language – keep jargon to a minimum and provide a glossary for any technical terms you use. The better you write, the better you will be understood by everyone, not just those with cognitive disabilities.

Also people with cognitive disabilities or dyslexia might use the read Out Loud feature built into the later version of Adobe Reader – or they might use other software to read out the document, so it is always a good idea to run through a PDF document using the inbuilt Read Out Loud feature to ensure it makes sense.

What is an accessible PDF?

In order for a PDF to be truly accessible two conditions must be met: the author must create a well structured, correctly tagged, PDF, and the person reading the document must be able to correctly configure his or her accessibility preferences in Adobe Reader.

Accessibility Preferences in Adobe Acrobat

There are a number of accessibility features in Adobe Acrobat (and Adobe Reader) that allow people to customise how they read a PDF document, in this section is a list of some of the most useful.

Read out loud feature

The Read Out Loud feature can definitely make some PDF files more accessible to people who are unable to access a PDF with their regular screen reader or those with an impairment such as dyslexia as previously mentioned that might also benefit from having the document read out loud.

To use the Read out loud feature select the View menu (Alt + V) then click on Read Out Loud  or press A and then select Read Current Page Only or press ‘O’ (shortcut  Shift+Ctrl+V) alternatively select   Read to End of Document or Press ‘E’ (shortcut  Shift+Ctrl+B)

You can also pause (Shift+Ctrl+C) and stop> the document once it has started to be read out.

Accessibility quick check

The Accessibility Quick Check cannot always correctly identify whether a PDF is accessible or not, but it can tell you whether the PDF is tagged or not or if there are glaring accessibility errors.

To run the quick check, choose Document > Accessibility Quick Check or press Ctrl + Shift + 6.

Note: There is a more advanced Full accessibility check available but only in Adobe Acrobat Professional.

Reflow

Reflow can be a very helpful feature, especially for people who need to enlarge the text, either within Adobe Reader or using an external screen magnifier. It is also good for people who use handheld devices or other devices that have small screens.

To enable reflow, either select View > Reflow or press Ctrl + 4.

Automatic scrolling

Automatic scrolling might be helpful for someone who has a motor disability so they can press fewer keys to read the document. To enable automatic scrolling, choose View > Automatically Scroll or press Ctrl + Shift + H. To Stop select the same option again. To Change scrolling speed press the Number key 0-9 or the Up and Down arrows.

Save as (accessible) text

You can save a PDF as plain text which can then be printed as Braille. As with other accessibility features, this only works if the reading order of the text is clear and if there are no complex tables.

Accessibility setup assistant

With Adobe Reader 7 there is  a more intuitive approach  to setting up general accessibility options To run the setup assistant choose Help > Accessibility Setup Assistant.... This will open a new window.

From this point, you can choose options for.

• Set options for screen readers
• Set options for screen magnifiers
• Set all accessibility options

Key principles of creating accessible PDFs

There are three types of PDF that you can create, unstructured, structured and tagged.

1. Unstructured PDF

This is a PDF created by scanning a document and is an image only (does not contain any real text). This type of PDF is the least accessible, Adaptive technology such as screen readers will not be able to access any information in the document.

2. Structured PDF

A structured PDF is an image with text (e.g. real-text) underneath. For simple documents this type of PDF is readable by assistive technology, for complex documents, such as ones containing multiple columns it will not be accessible.

Therefore this type of PDF is only partially accessible to Assistive technology.

3. Tagged PDF

A tagged PDF contains text (e.g. real-text) and it contains tags which help to identify order and structure of the document such as reading order - This is the most accessible type of PDF.

Creating an accessible PDF document from Microsoft Word using Adobe PDF Maker

One of the most common ways PDF files within organisations are created is from Microsoft Word documents. To do this you need to have the Adobe’s PDF Writer Plug-in installed.  Please note there are many other tools to create PDFs but using Adobe’s PDF Writer Plug-in is the easiest way to make accessible PDFs.

To create an accessible PDF from a Word document you must first ensure it has been well structured.

To do this:

1. Add alternative-text (e.g. alt-text) to all images in the Word document via the format picture option as shown in Fig 1 below.

Fig 1

 

2. Use styles for headers and lists. Specially use the Headings – Heading 1 to Heading 5 to mark up your section heading –these can be accessed via the Styles and Formatting menu in the Task Pane as shown in Fig 2. This structure can then be easily converted to the equivalent in the PDF document.

Fig 2

 

3. Create hyperlinks (e.g. links) in the text.

Then to create an accessible PDF from a Word document:

4. Go to: Adobe PDF (menu) > Change conversion settings. As shown in Fig 3 below [You only have to set it up once and save your new settings] There, verify that the settings of each of the tabs are as explained below:

Fig 3 Adobe PDF Writer menu in Word

 

Settings tab:

• Set conversion settings to “standard”
• Check mark all the options but “Attached source file to Adobe PDF”

Security tab:

• Uncheck the first two options “require a password to open the document” and “use a password to restrict printing and editing of the document and its security settings”.
• Check the options “Enable to copying of text, images and other contents” and “enable text access from screen reader devices for the visually impaired.

Bookmarks tab:

• Check the option “Convert Word Headings to bookmarks” as shown in Fig 4 below.
• Uncheck the option: “Convert Word styles to bookmarks and click on the OK button.

 

Fig 4 Convert Word Headings to bookmarks option selected

 

5. In Word, go to the Adobe PDF menu and select Convert to Adobe PDF

Save the file and the conversion process will then take a few minutes and you will have created an accessible PDF.

To find out more see the resources below:

Resources

Colour Contrast Analyser (for checking the colours you use in your PDF)

Accessibility Features in Acrobat Reader 7

Creating Accessible Documents with Adobe Acrobat 7.0 - (10.3 MB PDF. Requires Adobe Reader. If you don’t already have it download it from Adobe)

Reading accessible PDF documents with Adobe Reader 7.0: A guide for people with disabilities (3.8 Mb PDF. Requires Adobe Reader. If you don’t already have it download it from Adobe).

A List Apart: Facts and Opinions About PDF Accessibility. – Joe Clark