Accessible PDF

Accessible PDF

The PDF accessibility guidelines are primarily managed by the PDF Association, which developed the PDF/UA (Universal Accessibility) standard. This standard is officially recognized as ISO 14289-1 and provides detailed requirements for creating accessible PDF documents. It focuses on ensuring that PDFs can be navigated and understood by users with disabilities, including those who rely on assistive technologies like screen readers.

PDF/UA is complemented by WCAG (Web Content Accessibility Guidelines), which provide broader accessibility principles applicable to web content and digital documents, including PDFs. While WCAG is developed by the Web Accessibility Initiative (WAI) of the W3C, PDF/UA is tailored specifically to the structure and features of PDF documents

In relation to accessibility, people may refer to “tagged PDF”, which is a key aspect of making more accessible PDF publications. Tagging is a technique to allow page content (headings, text, images, tables) to present information to assistive technologies such as screen readers. These tags have no impact on the visual layout of a PDF. There is more to an accessible PDF file than tags, but an untagged PDF would not be considered “accessible”.

Important Parts of a PDF

Visual

The visual layer is what is seen on the screen. A primary benefit of a PDF is that it maintains the layout and appearance of the original document (also known as the “source document”) used to create the PDF. It looks the same when it is displayed, even across devices with different screen sizes, and when it is printed.

Content

The content layer contains basic formatting applied to text, like fonts and colors, and text formatted as a list or a table. When a user chooses to “reflow” a document, for example, for a more usable view on a small screen, the content layer is presented instead of the visual layer.

Tags

The tags layer contains the document’s structure, including headings, links, lists, and tables. This information supports assistive technologies, such as screen reading software which provides users access to the tags structure in this layer.

For example, screen reader users can quickly navigate to elements that are identified as headings in this layer.

Key Components of an Accessible PDF

  1. Tagged PDF Structure: Tags define the document’s structure (headings, lists, tables) and reading order for assistive tools.
  2. Alternative Text for Images: Descriptive alt text ensures images are interpretable for screen reader users.
  3. Readable Text: All text should be selectable and not embedded as an image.
  4. Proper Navigation: Includes bookmarks, headings, and a logical tab order for easier navigation.
  5. Accessible Links and Forms: Hyperlinks should be descriptive, and form fields must be labeled for screen readers.
  6. Color Contrast: Sufficient contrast between text and background for readability.
  7. Language Specification: The document’s primary language should be defined.
  8. No Reliance on Visuals Alone: Ensure information conveyed visually has a text-based alternative.

Tools for Checking and Remediation

  • Adobe Acrobat: It is a paid product and available on Windows and macOS. It includes accessibility tools for tagging, alt text, and checking compliance.
  • PAC – PDF Accessibility Checker: This is a free tool for testing PDF on Windows.  accessibility.
  • NVDA/JAWS: These are Screen readers to test accessibility on Windows
  • Talkback/Voiceover: These are in-built Screen Readers in Android and Apple devices respectively. PDF accessibility should be tested on mobile devices using these Screen Readers.
  • CommonLook: It provides a free PDF accessibility checker and professional services to help organizations achieve compliance with document accessibility standards, including WCAG, PDF/UA and Section 508.
  • Several other free and commercial tools and online services are available for remediating PDF files for accessibility.

For more information

Tags: PDF