Given all the ongoing discussions around web accessibility, one vital aspect is often overlooked. There is very little mention of accessibility when it comes to the world’s most popular file format, the PDF.
The Portable Document Format or PDF was introduced to the world by Adobe at the Windows and OS|2 Conference in January 1993. Adobe released the format as an open standard in 2008. Ever since then, it has been controlled by a committee of volunteer industry experts under the auspices of the ISO.
By April 2018, PDF made up 87% of all document formats found on the web. According to the PDF Association, by April 2016 there were:
- 2.2 billion PDF files on the (public) web (Google)
- 20 billion PDF files in Dropbox Airbus, Boeing and the US Dept. of Justice each have over 1 billion PDFs
- 2 billion PDFs opened every year in Outlook.com
- 73 million new PDF files saved every day in Google Drive & Mail
Given the numbers involved, it seems evident that PDF is very much the defacto standard for online documents. It makes it all the more strange that so little thought is given to ensuring that PDFs are read by as wide a range of users as possible. In the majority of cases, a report for the web is simply the print version exported as a PDF with no thought given to how it will be consumed digitally.
Creating reports for digital distribution is a huge part of what we do at Agent Jones.
We’ve spent a fair amount of time trying to figure out the best way to make the documents we produce accessible. Therefore we thought it useful to look at some of the techniques we’ve found for creating accessible PDFs.
Unfortunately, there is no single, quick step solution for making PDFs accessible. There is, however, a collection of best practice advice for creating truly accessible documents. One of the most comprehensive resources we found during our research is from the author, consultant and founder of accessibile.org, Kris Rivenburgh.
As part of our process in the studio, we start with the eleven ‘basic’ steps Kris outlined in his excellent 2019 article on PDF accessibility.
Make sure your document title is clear and descriptive, but not too long! A concise, relevant title doesn’t just help make your document more accessible, it will also help with SEO.
Setting the language for your PDF document means that assistive technologies can render text more accurately and screen readers can load the correct pronunciation rules. Additionally, visual browsers can display characters and scripts correctly.
Implement Heading Structure
Screen readers and other assistive technologies use headings to determine the logical order of content. A PDF with the correct structural hierarchy allows these applications to present the content in a structured manner which doesn’t rely on the document’s layout.
PDF tags provide a hidden, structured representation of the PDF content that is presented to screen readers. They exist for accessibility purposes only and have no visible effect on the PDF file. Tags are used to identify headings, lists and various other elements within a document. Additionally, purely decorative elements with no direct bearing on the content of the document can be tagged as Artifacts and will then be ignored by assistive technologies.
Accessibility can be enhanced by providing alternative text descriptions for images, charts, infographics and other items that do not translate naturally into text. Alternate descriptions are human-readable text that can be vocalised by text-to-speech technology for the benefit of vision-impaired users.
Adding additional information beyond the visible link text on your layouts adds a useful insight into the element you are linking to. This is particularly beneficial for screen reader users. Screen readers can read the default visible link text. But, replacing the screen text with meaningful alternate text for links in a PDF document can make links more accessible.
The logical order of PDF content for sighted users is also the visual order on the screen. For keyboard and assistive technology users, the tab order through content will determine the order in which these users can navigate the content. For example, some documents use multiple columns. To sighted users, the reading order is visually apparent. It flows from the top to the bottom of the first column, then to the top of the next column. If the document is not tagged correctly, a screen reader may read the document from top to bottom and across both columns, interpreting them as one column.
Images of Text = No-No
When an image contains words that are important to understanding the content, the text alternative should include those words. This will allow the alternative to accurately represent the image. Note that it does not necessarily describe the visual characteristics of the image itself but must convey the same meaning as the image.
Colour Contrast Ratio
Getting colour contrast right is a vital aspect of accessibility. Acceptable contrast ratios are defined within WCAG Guidelines for Level AA and AAA compliance. Keep in mind, there are different levels of contrast acceptability for small and large text. Test these using online tools like WebAIM’s Contrast Checker.
Don’t use colour to convey information
Colour should never be used as the sole method for conveying information. For example, using red to infer a negative value could easily be missed by a user with colour vision deficiency. All information conveyed through colour differences should also be conveyed explicitly in the text.
As Kris says in his article, with all these steps taken care of, your document might just score a 5 on the accessibility scale! There is a lot more that can be done to make a truly accessible PDF. For further (exhaustive) reading, we suggest checking out the W3C’s PDF Techniques for WCAG 2.0.
Find out how Agent Jones can help you create rich online documents and reports that reach more users. Click here to get in touch.