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Step 7: Auto Alt-Text Generation - LocalGov Drupal Walkthrough

Automatically generate accessible image descriptions using AI

Walkthrough progress

Step 7 of 12 • 3 minutes

Step 7 3 minutes

Auto Alt-Text Generation

Automatically generate accessible image descriptions using AI when you upload images.

Expected outcome

  • You understand how auto alt-text generation works
  • You've seen AI generate a description for an uploaded image
  • You know the accessibility benefits of proper alt-text

What is Auto Alt-Text Generation?

When you upload an image to the Media Library, Amazon Nova (opens in new tab)'s vision capabilities automatically analyse the image and generate a descriptive alt-text.

Automatic and instant

No extra clicks required. Simply upload an image and the alt-text field is automatically populated with an AI-generated description within seconds.

Why alt-text matters

Alt-text (alternative text) is essential for web accessibility:

  • Screen readers read alt-text aloud to visually impaired users
  • Search engines use alt-text to understand image content
  • Broken images display alt-text when images fail to load
  • WCAG compliance requires meaningful alt-text for all informative images

WCAG guideline: Alt-text should be concise (under 125 characters) and describe the image's content or purpose, not just "image of..." or "photo of...".

How to use Auto Alt-Text

  1. Go to the Media Library

    Click Content > Media > Add media > Image

  2. Upload an image

    Click "Add a new file" and select an image from your computer

  3. Wait for AI analysis

    Amazon Nova (opens in new tab) analyses the image and generates alt-text automatically

  4. Review and edit if needed

    The alt-text field is populated automatically. You can edit it if needed before saving.

Drupal media library showing an uploaded image with AI-generated alt-text: Group of people sitting around a table in a church hall with papers
The alt-text field is automatically populated when you upload an image

Example: What the AI sees

Here's an example of how the AI describes an image of a council meeting:

Council meeting image showing the AI-generated description

AI-generated alt-text:

"Group of people sitting around a table in a church hall with papers"

78 characters Well under the 125 character WCAG recommendation

Best practices

Do Don't
Review AI-generated alt-text for accuracy Accept alt-text without checking
Add context the AI might miss (names, locations) Leave generic descriptions when specific ones help
Keep alt-text concise and meaningful Start with "Image of..." or "Photo of..."
Use empty alt="" for purely decorative images Add alt-text to decorative images
Important Always review AI-generated alt-text. The AI describes what it sees, but you may need to add context about who or what is in the image.

For technical readers

AWS Service Purpose
Amazon Bedrock (opens in new tab) Hosts the foundation model for image analysis
Amazon Nova (opens in new tab) Vision model that analyses images and generates descriptions

Need help?

If you're stuck, check the troubleshooting section or contact us.