Make Existing PowerPoints Accessible
Missing Alt Text
Missing alt text notes images that do not have alt text or are not marked as decorative. Visual information needs an equivalent text description. Descriptions can be provided by adjacent text, a figure caption, or the alt text field. Adjacent text and figure captions are accessible to assistive technology and provide context, purpose and meaning of visual content to all users. Alt text relays information via code that is read by screen reader software to aide users to understand visual information. Decorative images are graphics that are included solely for aesthetic purposes or are accompanied by equivalent text description.
Who missing alt text affects
Visual information must have a text equivalent to ensure blind and visually impaired learners have equitable access to learning material. Shapes, images, charts, SmartArt and any visual information must have a text equivalent.
The following recording demonstrates screen reader software reading three examples of alt text: one with no description, one with poorly written alt text, and one example of effectively written alt text.
How to fix it
In the Check Accessibility Pane, PowerPoint will flag Missing alt text as an error.
Select the Missing alt text error and type a description and click Save.
The Alt Text Pane can also be opened by selecting the image and:
In the Alt Text Pane, users can replace an existing description, approve automatically generated descriptions, or mark a graphic as decorative.
All informative images need alt text. Alt text can be provided in the alt text field (explained above), a figure caption, or adjacent equivalent text. Consult the Alternative Text Quick Start Guide for further guidance. However, any graphic included solely for aesthetic or decorative purposes or is accompanied by equivalent text description should be marked as decorative.
Intelligent Services: Review auto-generated description
By default, PowerPoint will generate alt text for images when they are added to a slide. The PowerPoint Check Accessibility tool will flag those images with “Review auto-generated description.” Auto-generated descriptions must be reviewed and generally are not sufficient. When viewing the alt text for a graphic, you can check Approve alt text, however, PowerPoint’s auto-generated descriptions are rarely accurate and never include sufficient detail to be a sufficient text equivalent.
Anything (file name, random characters, or auto-generated descriptions) in the alt text field passes the Check Accessibility tool. Ensure you review all alt text for clarity and accuracy.
How to prevent it next time
Ensure your workflow includes adding alt text each time you add an image. Learn how to write alt text.
Learn how to best add descriptions, figure captions, or alt text in PowerPoint.
Read Alternative Text Quick Start Guide and related chapters in the Accessibility Handbook for Teaching and Learning.
Using AI to describe images may be a useful starting point for writing alt text, descriptive figure captions, or text alternatives of visual information. Always review machine-generated content for usefulness and accuracy.
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Move to the next page to address Hard-to-read Text Contrast or select the next error you want to fix.
