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How to add alt text to images in a PDF
Short answer: Each meaningful image in a PDF needs alternative text stored on its Figure tag; purely decorative images should be marked as artifacts so screen readers skip them. In Acrobat Pro, use Accessibility › Set Alternate Text. Better, add alt text in Word before exporting. Write what the image means in context in one or two sentences, and include any important text that appears in the image.
Decide first: meaningful or decorative?
- Meaningful: photos of people or events, logos, charts, maps, flyers, QR codes, diagrams. Need alt text.
- Decorative: lines, borders, background shapes, stock decoration that adds nothing. Mark as artifact.
Writing good alt text
| Image | Weak | Better |
|---|---|---|
| Event photo | “Photo” | “Volunteers in red shirts planting flowers around a tree at City Planting Day” |
| Logo | “Logo” | “City of Medical Lake logo” |
| Flyer image | “Flyer” | “Farmers market, Saturday May 9, 9 AM to 1 PM on Lake Street” |
| Chart | “Chart” | “Water rates rise from $40 to $60 per quarter between 2025 and 2027” |
| QR code | “QR code” | “QR code linking to the recreation program sign-up page” |
Tips: don’t start with “Image of”; include text shown in the image; say what matters for the document, not every visual detail.
Adding it
- In Word (best): right-click the image › View Alt Text. Mark decorative images as decorative. Export with accessibility tags.
- In Acrobat Pro: Accessibility › Set Alternate Text walks through each figure.
- Automated: our tool writes alt text for every image using an AI model that sees the image and the text around it, and marks decorative images and scan backgrounds as artifacts. Every report lists all descriptions so you can review them.
Common mistakes
- File names as alt text (“IMG_2041.jpg”).
- Identical alt text on every image.
- Placeholder text such as “image 1”. Automated checkers count it as present, but it tells a listener nothing.
Frequently asked questions
- How long should alt text be?
- Usually one or two short sentences. Complex charts need a short alt text plus a fuller description in the surrounding text or a data table.
- Should a logo have alt text?
- Yes, if it identifies the organization: for example 'City of Springfield logo'. A decorative flourish next to it does not.
- Can AI write alt text?
- AI can draft good descriptions, especially for photos and flyers with text. A person who knows the document should confirm they say what matters.