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PDF Accessibility — Image Has No Alternate Text

criticaldocument scope

This PDF contains one or more images that have no alternate text — a text description that a screen reader can read aloud in place of the image. A blind user encountering these images hears nothing, or hears a generic announcement like 'figure,' with no information about what the image shows. Photos, charts, diagrams, maps, signatures, logos, and agency seals in PDF documents all require alternate text if they convey information.

Who Is Affected

Blind and low-vision screen reader users receive no information from images lacking alternate text. For a government document, this could mean missing a photograph identifying a project location, a chart showing key data, an agency seal on an official letter, or a map showing a service area.

What This Means

In a PDF, alternate text for images is stored in the Alt entry of the image's <Figure> tag. When a screen reader encounters a Figure tag, it reads the Alt text in place of the image.

Images that require alternate text:

  • Photos illustrating document content
  • Charts and graphs (alt text should describe the key finding)
  • Maps (alt text should describe purpose; see also Document Type: CAD/GIS Map for maps requiring a full accessible alternative)
  • Logos and agency seals when they convey identity
  • Signatures on official documents (alt text: "[Signature of Director Jane Smith]")
  • Diagrams and flowcharts

Decorative images (borders, background textures, purely ornamental graphics) should be tagged as Artifact rather than <Figure> — this tells screen readers to skip them entirely. An artifact tag is the PDF equivalent of alt="" in HTML.

Fix: Document

Adding alt text to a Figure tag in Adobe Acrobat Pro:

  1. Open the Tags panel (View → Show/Hide → Navigation Panes → Tags)
  2. Find the <Figure> tag for the image (you can right-click a <Figure> and choose "Highlight Content" to identify which image it corresponds to)
  3. Right-click the <Figure> tag → Properties
  4. In the Tag tab, enter the alternate text in the "Alternate Text" field
  5. Click OK and save

Writing effective alt text for PDF images:

  • Photos: describe what is shown and why it matters in context
  • Charts: state the key finding: "Bar chart showing water quality index scores by district, 2023. Scores range from 78 to 94."
  • Maps: describe purpose and key features; for complex maps see the DOC-CLASS-cad-gis-map article
  • Logos/seals: "[Agency Name] official seal" or "City of [Name] logo"
  • Signatures: "[Signature of First Last, Title]"
  • Decorative dividers or borders: mark as Artifact, not Figure

Marking decorative images as Artifact:

  1. In the Reading Order tool: select the image region → click "Background" in the Reading Order panel
  2. In the Tags panel: delete the <Figure> tag for the decorative element (the image content will become an artifact)

From the source file:

If remediating from a Word document, add alt text to images before export: right-click image → Edit Alt Text → fill in the description → check "Mark as decorative" for ornamental images. Export with accessibility tags enabled.

Standard Reference

Primary WCAG criterion addressed:

Helpful Tools

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