Fixing Image Accessibility Issues in Canvas (UDOIT Guide)

Images can enhance course content, but without appropriate alternative text, they create barriers for students.

Purpose of This Guide

This guide provides practical support for resolving image accessibility issues identified by UDOIT in Canvas.

If your UDOIT report flags problems such as missing alternative text, filenames used as descriptions, overly long or generic alt text, or decorative images not properly marked, this resource will help you:

• Understand what the alert means
• Learn why the issue affects accessibility
• Apply clear, step-by-step fixes in Canvas
• Improve clarity and accessibility throughout your course

Whether you are responding to a specific UDOIT alert or proactively reviewing your course materials, this guide will help you ensure that images support learning rather than create barriers.

Why This Matters for Students

Images can clarify complex ideas, illustrate examples, and provide visual engagement. When images are used in course content, their meaning must also be available in text form.

Alternative text, or alt text, ensures that the purpose or content of an image is communicated when:

• A student uses a screen reader
• An image does not load
• Images are disabled or blocked
• A student relies primarily on text-based access

When alt text is missing, unclear, or excessive:

• Important information may be lost
• Navigation becomes confusing
• Cognitive load increases

Clear and purposeful image descriptions ensure that all students can access the same instructional content, regardless of how they access your course.

Images Explained

An image in Canvas may serve one of two primary purposes:

Informative Image
An image that conveys important instructional content, such as a chart, diagram, screenshot, or labeled example. Informative images require meaningful alternative text that communicates the image’s purpose or key takeaway.

Decorative Image
An image used for visual design, spacing, or emphasis that does not add instructional meaning. Decorative images should be marked as decorative so assistive technologies skip them.

When writing alternative text, focus on what the image contributes to the page. The goal is not to describe every visual detail, but to communicate the information or function the image provides.

If removing the image would remove meaningful instructional content, it needs alt text. If removing the image would not change the meaning of the page, it is likely decorative.

Image Issues UDOIT May Identify

UDOIT may flag the following image accessibility issues:

• Alternative text uses a filename rather than a descriptive label
• Image does not include an alt attribute
• Alternative text appears to be a generic placeholder
• Input image may be missing an alt attribute
• Alternative text is too lengthy
• Image description is identical to alt text
• Decorative image does not have empty alternative text
  

The section below explains what each alert means and how to resolve it in Canvas.

Issue-by-Issue Breakdown

Issue 1: Alternative Text Uses Filename Rather Than a Descriptive Label

What UDOIT Is Flagging
The alternative text contains a filename such as “image1.png”, “screenshot_final_v2.jpg”, or “final_chart_v3.jpg” instead of a meaningful description.

Why This Matters
A filename does not communicate the meaning or purpose of an image. When images do not load, are disabled, or are accessed using assistive technology, a filename provides little or no useful information

In these situations, the filename is read aloud instead of a meaningful description, leaving students without the information the image was intended to convey.

If the image contains instructional content, that information may be lost.

How to Fix It in Canvas

1. Open the page in Edit mode.
2. Select the image.
3. Open Image Options.
4. Replace the filename in the Alternative Text field with a concise description of the image’s purpose or key takeaway.
5. Click Save.

Design Guidance
Write alternative text that captures the key message or function of the image within the page. Avoid referencing file names, formatting, or visual details that do not support learning. The alternative text should communicate what a student needs to understand from the image.

Issue 2: Image does not include an ‘alt’ attribute

What UDOIT Is Flagging
The image does not have alternative text and has not been marked as decorative.

Why This Matters
If an image has no alternative text, its meaning may be unavailable when images do not load or when students rely on text-based access. If the image conveys instructional content, students may miss essential information.

How to Fix It in Canvas

1. Open the page in Edit mode.
2. Select the image.
3. Open Image Options.
4. Add meaningful alternative text, or mark the image as decorative if it does not convey instructional meaning.
5. Click Save.

Design Guidance
Every image must be evaluated. If it communicates instructional content, it requires alt text. If it does not, it should be marked as decorative.

Issue 3: Alternative text appears to be a generic placeholder

What UDOIT Is Flagging
The alternative text includes vague terms such as “image,” “photo,” or “graphic.”

Why This Matters
Generic labels identify the format of the image but do not explain what students are meant to learn from it.

How to Fix It in Canvas

1. Open the page in Edit mode.
2. Select the image.
3. Open Image Options.
4. Replace the generic placeholder with a concise description of the image’s meaning or function.
5. Click Save.

Design Guidance
Alt text should primarily answer:
What does a student need to learn or understand from this image in this specific context?

The answer depends on the type of image:

Contextual or Informational Images
What information does this image provide that supports understanding of the surrounding content? Describe the key idea or takeaway.

Functional Images (Buttons or Links)
What action does this image perform, and why would the student use it? Describe both the function and its purpose.

For example, use “Search the course site” rather than “Magnifying glass icon.”

Text-Heavy Images
What does the text in this image communicate? What key message is conveyed through the text in this image? Ensure that critical wording is included in the alt text or presented in the main body of the page.

Decorative Images
Would students lose important information if this image were removed? If not, it should be marked as decorative.

Issue 4: Input image may be missing an ‘alt’ attribute

What UDOIT Is Flagging
An image that students can click, such as a button or icon, does not include alternative text.

Why This Matters
When an image acts as a button, its alternative text becomes the label that tells students what the button does. Without it, students may not know what will happen when they select it.

If the image is used to submit work, start a quiz, search, or open something, unclear or missing alt text can make that task difficult to complete.

How to Fix It in Canvas

1. Open the page in Edit mode.
2. Select the image used as a button.
3. Open Image Options.
4. Add alternative text that clearly describes the action and purpose, such as “Submit Assignment” or “Open Quiz.”
5. Click Save.

Design Guidance
When an image performs an action, write alternative text that includes essential text and describes the action rather than the appearance.

Issue 5: Alternative text is too lengthy for optimal screen reader experience

What UDOIT Is Flagging
The alternative text contains a long or paragraph-length description.

Why This Matters
Alt text should be concise. Lengthy descriptions can interrupt the flow of content and overwhelm users who rely on text-based access.

Canvas limits alternative text to approximately 120 characters.

How to Fix It in Canvas

1. Open the page in Edit mode.
2. Select the image.
3. Open Image Options.
4. Revise the alternative text to summarize the key message of the image.
5. Move detailed explanations into the surrounding text within the page if needed.
6. Click Save.

Design Guidance
Keep alternative text focused on the most important takeaway. If the image requires a detailed explanation, provide that explanation in the main body of the page instead of in the alt text field.

Issue 6: Decorative image does not have an empty alternative text

What UDOIT Is Flagging
An image that appears decorative includes alternative text instead of being marked as decorative.

Why This Matters
If decorative images include alternative text, they may be announced unnecessarily, increasing cognitive load and distracting from instructional content.

How to Fix It in Canvas

1. Open the page in Edit mode.
2. Select the decorative image.
3. Open Image Options.
4. Mark the image as decorative.
5. Click Save.

Design Guidance
If removing the image would not change the instructional meaning of the page, it is likely decorative and should be marked as decorative.

Workflow Strategy

If your UDOIT report shows multiple image alerts, begin by reviewing decorative images. These are often the quickest to resolve by marking them as decorative in Image Options.

After addressing decorative images, prioritize instructional images that:

• Convey essential course content
• Include charts, diagrams, or screenshots
• Function as buttons or links

Resolve missing alternative text first, as this creates the greatest accessibility barrier. Then refine generic or filename-based alt text.

Work page by page in Canvas rather than addressing alerts individually within UDOIT. This approach helps maintain consistency and ensures that image descriptions align with surrounding content.

After making updates, re-run UDOIT to confirm that all image-related alerts have been resolved.