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How to recognise accessible PDFs - PDF in Drupal part 3

Senior Technical Writer
Apr 18, 2016

While in the past accessibility was often only perceived as a nice extra, it is quickly becoming the norm: in most countries legislation dealing with accessibility currently 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.

As an addition to our PDF in Drupal series (PDF in Drupal part 1
and part 2), we researched the subject of accessible PDFs: how can writers create content in a way that it becomes accessible to users with disabilities? We’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 blogpost Publishing a code sample book from Stackoverflow to LeanPub using Drupal and GitLab.

Other tips to improve accessibility:##

  • Show the logical structure of a document by inserting headers
  • Add navigation labels, such as headings
  • Choose software that creates accessible documents (if this is for a web application, you could integrate an open source library like iText that supports accessible PDF)

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.

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 to access and check content##

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.

    Available for Windows 7, 8, 10 and OS X.

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

    Windows, OS X and Linux-based operating systems have built-in screen magnifiers.

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 the 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:

Steve is involved in the work of the content team of Pronovix: writing and editing blog posts, articles, web copies and technical documents. He is responsible for social media campaigns and content strategy.

Besides this, he's translating books from English to Hungarian for a publishing company. Steve has a journalist/writer background, his works are frequently published in various online and printed journals.

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