• The official voice of STC and the tech comm community

Talking Usability: Lessons Learned About PDF Accessibility

150 150 James Cameron

By David Dick | STC Fellow


Many of us hold this assumption to be true—we can convert text documents into Accessibility-compliant Portable Document Format (PDF) documents by saving them as PDF. Any desktop publishing tool can create PDF files using “Save as Adobe PDF”; however, the PDF files it creates are not always Accessibility-compliant for screen readers.

One of the tasks of my current job is to convert documents into Accessibility-compliant PDFs. A document is considered accessible if it can be read by people with disabilities. This includes access by people who are mobility impaired, blind, low vision, deaf, hard of hearing, or who have cognitive impairments. These users rely on screen readers to dictate the contents of the document to them, including images, tables, and graphics. The reason to convert a source file to a PDF is because PDF is universally compatible with screen readers, whereas a source file saved in its native format might not be.

The instructor teaching me how to create Accessibility-compliant PDFs said that he spends many hours correcting accessibility errors in PDF documents. Unfortunately, he had to correct the accessibility errors again whenever the source document changed. It was apparent to me that the seamless conversion of a source document to an Accessibility-compliant PDF document begins with an Accessibility-compliant source document.

The following are a few tips I learned to build accessibility into source documents.

  • Document Title. To a search engine, a PDF document is just another web page. Search engines read the “Title” document information field. If it finds nothing, the search engine’s indexer tries to guess the document’s title by scanning the text on the first few pages. This usually doesn’t work, and produces incorrect and improperly formatted results. If the indexer finds text in the Title field, it will use it, regardless of whether that text is meaningless or not.
  • Headings. Never create headings by applying a bold font to titles and increasing the font size to a title. Best practice is to directly modify titles using Heading styles. When converting the source document to PDF, Heading 1, 2, 3, etc., convert to heading tags, which create structure for screen readers.
  • Alternative text. Alternative text (Alt text) allows the content and function to be understood by screen readers, which is why Alt text is required for all images, graphs, diagrams, and tables.
  • Tables.  For tabular data, use the correct table mark-up. Avoid using spaces, tabs and line breaks to emulate the table layout. Tables require headings, which are added by modifying the Table Properties. To a screen reader, a table without a table header is only an object with columns. For Word documents, select the Table Properties, select the Row tab, and check “Repeat as header at the top of each page.”
  • Hyperlink Text.  Hyperlink text requires a description of the link destination instead of providing only the URL. Mask the URL with an appropriate alternate text so that screen reader users can easily determine its purpose. For example, the statement, “The STC Home Page provides links to member information” which is more descriptive and informative than “click here”, “read more”, “for more information see…”  Use the Screen Tip option to insert a description about the link.
  • Use of Paragraphs (¶) to create white space. Screen readers read paragraphs (¶) as empty space. To create white space between titles, bullets, and headings, modify the style’s paragraph spacing.

Use a professional PDF editing tool such as Adobe Acrobat Pro to test the document for accessibility and correct errors. I encourage you to test the PDF document with a screen reader to validate the information follows properly. Tags define the reading order and identify headings, paragraphs, sections, tables and other page elements. You might have to make minor manual corrections to the tags so that the information flows in the correct order.

When accessibility is incorporated into the source file, the PDF requires fewer corrections. If changes are only made in the PDF document and not to the source file, accessibility work will need to be done each time the source file is updated. When you create accessible documents for people with vision deficiencies, you make information usable for all.

Good resources to learn about PDF accessibility:

UC Berkeley Event, May 2008, PDF Accessibility and Usability Issues. In this presentation, Sean Keegan, a premier expert on document and Web accessibility, addresses usability and accessibility issues of PDFs, strategies for the creation of accessible electronic documents, and the appropriate use of software applications to ensure accessibility of Web documents.

European Blind Union. Making Information for All provides guidance on how to make electronic documents accessible for assistive technology.

Adobe Acrobat DC Repair describes the process for making PDF documents accessible.