This site follows WCAG 2.1AA accessibility guidelines. For support or alternative formats, contact the AI and Accessibility project team.

Generating Alternative Text

Learning Objectives

By the end of this lesson, users will be able to:

Define what ALT text is an explain it's role in digital accessibility and Universal Design for Learning (UDL)
Use AI tools to generate alt text for images
Evaluate and revise AI-generated alt text to ensure accuracy, clarity and inclusivity.
Apply accessibility guidelines (AODA/WCAG 2.2) when creating visual content for online learning.

A neoclassical building with tall stone columns stands on a quiet city street. A cyclist rides past while a pedestrian walks along a sidewalk lined with trees and flowers. Modern skyscrapers tower in the background beneath a clear blue sky.

What is Alternative Text?

Alternative text is a short written description of an image that explains what's being shown. It helps people who can't see the image, like individuals using screen readers, understand what the image is about.

<-- Click on the image to see alternative text.

Understanding Screen Readers and Accessibility

Watch this quick video that highlights the importance of alternative text and how simple changes can make visual content more inclusive and accessible.

What is Wcag?

The Web Content Accessibility Guidelines (WCAG)

WCAG is a guideline for making websites and online tools accessible to everyone, including people with disabilities. This video from Silk tide explains what WCAG is, why it exists, and how following the guidelines helps create a fair, inclusive web.

Good Quality Alt Text Vs. Poor Quality Alt Text

Good Alternative Text Example:

"A teacher sits at a round table with two students, smiling as they look at a colourful book together. One student uses a wheelchair, and the group appears engaged in a bright, inclusive classroom."

Why it's good:

Descriptive and specific
Focuses on key visual details
Inclusive and respectful language
Supports accessibility context

A teacher sits at a round table with two students, smiling as they look at a colourful book together. One student uses a wheelchair, and the group appears engaged in a bright, inclusive classroom.

Poor Alternative Text Example

"People in a room."

Why it's poor:

Too vague
Lacks context (who, what where)
Doesn't describe actions, emotions or setting
Not useful for someone using a screen reader

Using AI to Generate Alternative Text

Practice generating alternative text with AI

Steps:

Save or screen capture at least 1 image below.
Open an AI tool linked below (ChatGTP, Canva AI, Copilot or one of your choosing.)

Use this prompt:

"Write alt text for this image that follows WCAG 2.2 accessibility standards."

Compare the AI-generated alternative text to the examples below.

A bright red apple sits on a smooth white marble surface with soft lighting and a faint shadow beneath it.

Chat GTP

A smiling teacher helps two young children paint colorful pictures at a classroom art table, with jars of paint and student artwork on the wall behind them.

Canva AI

A busy Times Square scene at dusk with yellow taxis, pedestrians, and large illuminated billboards advertising Broadway shows and global brands under tall glass skyscrapers.

Copilot

Reflection & Evaluation of Activity

What did AI get right?
What needed human revision?
Why is human review important for accessibility?
Is it concise?
Is it Accurate?
Is it Inclusive?

Step By Step Process for Using AI to Write Alt Text

Step 1: Upload or describe the image clearly.

Include what's visible and what's relevant.

Step 2: Ask AI for a neutral description.

Prompt it to avoid opinions, emotions or assumptions.

Step 3: Review the response.

Ask: Does this describe what's visible?

Is anything added that can't be confirmed?

Is it concise and inclusive?

Step 4: Revise for WCAG 2.2 compliance.

Why the Revision is Needed

AI-Generated Alt Text:

A motivative child enjoys playing with cars, showing creativity and focus.

At first glance, this description might seem fine. It's positive and descriptive but according to WCAG 2.2 (Non-text content 1.1.1), alt text must describe what's visible and necessary for understanding the image, not what the AI assumes or interprets.

Here's what went wrong:

Assumed Emotion or State of Mind
The words "enjoys," "imaginative" and "showing creativity" describe feelings or traits that are not visually verifiable.
We can't see enjoyment or imagination, we only see the child's actions.

Missing key visual details:

The alt text doesn't mention the child's glasses, the toy cars, or the rug, which are all important for someone using a screen reader to form a mental image.

Too interpretive, not objective:

AI often adds storytelling language because it's trained for engagement, but accessibility requires neutral, factual language.
Adding assumed intent ("showing creativity and focus") turns the alt text into a narrativize, not a description.

💡Key Takeaways: Using AI to Create Effective Alt Text

Alt text describes what can be seen, not what can be assumed

It should communicated essential visual details for anyone using a screen reader. Avoid adding emotions, opinions, or intentions that can't be visually confirmed.

Keep alt text concise and meaningful

Most alt text should be under 125 characters and include only details that add understanding (people, actions, setting, or important objects).

AI is a starting point, not the final step

AI tools like ChatGTP, Copilot, or Canva Magic Write can gernerate drafts quickly, but they can add emotion or assumptions. Always review and edit for accuracy, and WCAG compliance.

Human judgment ensures accessibility.

Accessibility requires context and care. Only humans can decide which visual elements are important for understanding the message of an image.

Follow WCAG 2.2 and AODA standards

The guidelines help ensure content is perceivable, understandable, and inclusive for all users.

Wcag 2.1 Guideline

Wcag 2.1 Images of Text

Wcag 2.1 Media Description (Prerecording)

Accessibility Checker

References

Alcázar, J. (2022). How blind people view pictures online. #AltText #accessibility [Video]. YouTube. https://www.youtube.com/watch?v=HBiTPoST2FM

Level Access. (2024, October 9). WCAG 101: Understanding the Web Content Accessibility Guidelines. https://www.wcag.com/resource/what-is-wcag/

MasterWriter. (2025, June 12). The pros and cons of AI writing tools. https://masterwriter.com/the-pros-and-cons-of-ai-writing-tools/

Silktide. (2022). WCAG for beginners – What are the Web Content Accessibility Guidelines? [Video]. YouTube. https://www.youtube.com/watch?v=5H1JGdqLrWo

Tri Julianto, I., Kurniadi, D., Septiana, Y., & Sutedi, A. (2023). Alternative text pre-processing I. Jurnal Nasional Pendidikan Teknik Informatika (JANAPATI), 12(1), 67–77. https://doi.org/10.23887/janapati.v12i1.59746

Page updated

Report abuse