Alt Text: Writing Alternative Text

Images are one of the biggest concerns regarding accessibility for our students. Canvas offers us many ways to incorporate images into our courses, and our students benefit greatly from visuals as examples and engagement. However, when using an image, you must include alternative text (also known as ALT text). This enables a screen reader to read the description of the image to the student, much like you would describe a scene or picture over the phone to a friend.

With practice, the step of adding an alt text becomes second nature. Take a look at how to become an alt-text expert below. (Excerpted from the ALLY Website Write Accessible Content Links to an external site..

Why is the image here?

Ask yourself what the purpose of an image is. Is it to give a page visual appeal? Or to give a sighted user a visual reference of what to expect? Is the image something all users need to consume to understand your content? You can use both Ally and the Canvas text editor to differentiate between a decorative image and an informative content image.

  • A decorative image is one that only provides decoration. If it helps someone better understand the content in any way, it's informative and needs alternative text. 

Writing Alternative Text

You will come across a field for alt text when uploading an image. If the image is already in your course, you can access this by clicking the image, then click on the "Add Image" button in the editor. You can also click on the accessibility indicator (the small gauge icon). 

For decorative images, leave the alt text field blank and click on the "Decorative image" box. When a screen reader is reviewing the page, it will ignore the image. 

For informative images, you don't want the screen reader to skip the image, because students using that tool will miss the content. Include a brief (max 75 characters) description. 

A few more tips for writing alternative text:

  • You don't need to say "Image of" as the assistive tools already know it is an image. Be concise, clear, and descriptive.
  • Do not use the same alt text for every image, such as "Image illustrating associated text." It is meaningless and adds clutter.
  • If the image requires a longer description, create another Canvas page with that longer description written out, then link to that page from a clearly written caption below the image. 

Additional resources for writing Alt Text: