Accessible PDFs

While in the past accessibility was often only perceived as a nice extra, it is quickly becoming the norm: in most countries accessibility legislation only affects web pages, but PDF documents might follow soon. With good cause: worldwide approximately 285 million people are visually impaired and have difficulties to read online documents without assistive technologies.

I researched the subject of accessible PDFs: how can writers create content in a way that it becomes accessible to users with disabilities? I’ll highlight checking mechanisms and tools and end with listing three types of the available assistive technologies that make content accessible.

What is an accessible PDF?

PDF, the Portable Document Format, is a widely used standard document type on the internet. Users can convert electronic documents and scanned images into a PDF file, and distribute it easily via email. When implemented properly, PDF content becomes accessible to users with disabilities such as blindness and low vision or of a cognitive or learning nature (e.g. dyslexia).

How to make PDF accessible

Document authors can choose from a range of possibilities to create accessible PDFs. A few examples.

Tags

Tags contain little pieces of metadata creating a hidden structured, textual representation of the content, thus becoming available for screen reader programs and other assistive software. Tagging doesn’t influence the visual integrity of a PDF file: the look of the document remains the same. By adding tags, the content creator defines the exact order of reading, which makes it easier for users to interpret the document structure and navigate through the content.

Alternate text (alt text)

Alternate text provides text-based information about the hyperlinked web page or the inserted image.

If an image is not visible due to software errors or because the user is visually impaired, the alt text will provide a text equivalent to the missing information. The example shows an alternate text that describes an image, taken from the blog post Publishing a code sample book from Stackoverflow to LeanPub using Drupal and GitLab.

iText

iText has a free downloadable PDF library that can be used on the Java Virtual Machine, on the .NET platform as well as on Android and Google App Engine. It makes easy to create PDFs accessible.

Checking accessibility

Ideally, checking the accessibility of a PDF document should the last phase in its creation process. Most PDF creating software provide this possibility.

Software applications like PAC 2 offer possibilities to check the accessibility state of your document.

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According to Adobe’s guide about creating accessible PDFs, accessibility issues often appear in

• documents containing only scanned images of text (and without content available to screen readers)
• documents without tags
• documents without alt text on images or on links

Assistive technologies

Authors can use the same assistive technologies that are used by their audience to test the accessibility of a created document.

Text-to-speech software provides auditory feedback for documents or website content:

• The Read and Write for Google Chrome extension helps users with cognitive or learning difficulties access Google Docs documents and webpages.
• Balabolka is downloadable TTS software. It has a portable version that can save on-screen text as WAV or MP3 files.

Speech-to-text (voice recognition) software takes and transcribes audio content into written words.

Screen magnifier software makes it possible to enlarge screen content and provide auditory feedback.

Conclusion

The goal of accessibility is to ensure that every person, with or without disabilities, has equal chances and possibilities to access your content. Creating accessible PDF files can help to reach that goal. With quickly changing technology, creation process of accessible documents gets more complex, but the need to provide them grows at the same time.

We’d like to highlight some sources providing information and tools:

• Learn more about accessible Adobe PDFs.
• You can read more about PDF accessibility on WebAIM.org.
• The PDF Universal Accessibility Standard (ISO 14289).
• You can find additional free assistive software here.

You can learn more about PDFs in Drupal from the first part and the second part of our blog post series.

Would you like an open source Java daemon that generates accessible PDF? We are considering to build one! Fill out the form to stay informed!

Originally published at pronovix.com on April 18, 2016.