Creating Accessible PDFs

Harvard University mandates that all PDFs distributed externally (via email or online) meet these accessibility standards. This page outlines what designers can do when creating InDesign files to make the content accessible.

Main Guidelines

  1. Content can be read in logical order (right to left; top to bottom).
  2. Include descriptive headers.
  3. Indicate different content types: paragraphs, links, heading, and figures.
  4. Use good color contrast.
  5. Images should either have substantive alternative text or be tagged “artifact.”

Creatives are responsible for:

  1. Starting with an accessible source document.
  2. Ensuring text color contrast ratio is met.
  3. Adding metadata.
  4. Including tags.

1. Accessible Source Document

An accessible source document should be provided by Project Manager:

  • Includes metadata: title, author, language, description.
  • Content is laid out in a logical way that’s easy to follow using descriptive headings and link text.
  • Alternative text is provided for images that are important to the context of the document (if substantive alt text is not included, tag image as “artifact”).
  • Inaccessible non-text content such as scanned documents or photos of documents, need to be converted to accessible digital text.
  • Cannot contain media that flickers or flashes more than three times in one second.

2. Color

  • Avoid using color alone to convey meaning.
  • Ensure text contrast ratio is met.
    • Check color contrast: 4.5:1 or greater for standard size text; 3:1 for large text (18 pt Regular; 14 pt Bold).

3. Add Metadata

  • Add document title (must be displayed), author, language, description.
    • If using InDesign go to File > File Info to add this information.
  • Security Settings:
    Make sure to provide permissions such as enabling text access to screen reader devices for the visually impaired. This is done when exporting the file.

4. Include Tags

Tags communicate the structure of the document to assistive technology.

  • All tags should be nested inside a <Document> tag, this should be automatic after exporting.
  • Include page numbers using Markers feature in InDesign to support accessibility and facilitate navigation.
  • Use Paragraph Styles to organize content, and create hierarchical tags (<h1>, <h2>, <h3>…. ).
  • Keep copy together in linked text boxes so the screen reader reads the information together.
    • Keep Lists in linked textboxes that contain the descriptive title and subsequent list.
    • Use the Table tool to make tables because it provides the correct tag structure. Tables should have descriptive headings.
  • Link text should be unique and should describe the topic or purpose of the link. Do not use “click here” or “read more.”
  • Any decorative items or images should be tagged as Artifacts.
    • To do this using InDesign, right-click on the object(s) and select Object Export Options > Tagged PDF > Apply Tag: Artifact > Done.
  • Add substantive alt text for all non-decorative images
    • Alt text should be provided by the Project Manager or Client.
      • Alt text should convey the “why” of the image as it relates to the document content
      • Short & descriptive like a tweet. Nonsubstantive alt text like “image of dog” shouldn’t be included. If substantive alt text can’t be included, an image should be tagged <Artifact>.
    • The Client can add alternative text using Acrobat, however, if the document is re-exported from InDesign that data will not be in the document.
    • To add alternative text this using InDesign, right-click on the object(s) and select Object Export Options > Alt Text > From Structure > Done.

If There Are Subsequent Edits in Adobe Acrobat

Any changes made in Acrobat are not in the InDesign document, therefore, those changes will be lost if we need to edit the original InDesign file for content changes.