Q: I heard that colour contrast is important for accessibility, is there a standard to use for slide decks? What are some tools that I can use to make sure that my slides meet the standards?
A: Colour contrast plays a huge factor for accessibility because it’s also tied to legibility of the text we see. We recommend following the Web Content Accessibility Guidelines (WCAG) and ensure that your text and images of text has contrast ratio of at least 4.5:1, to successfully pass the minimum requirements (AA), but encourage that you meet the enhanced requirements (AAA) wherever possible. You can check the contrast ratio by using the WebAIM: Contrast Checker or the built-in accessibility checker inside PowerPoint.
Using WebAIM: Contrast Checker
To check the contrast ratio, we use the WebAIM contrast checker. It has the colour pickers for you to easily pick the foreground (text) and the background colours from your slides.
Once you have your slides open and with the WebAIM contrast checker also open on the side, you can check the colour contrast by following these steps:
- Select the coloured box located under the Colour picker
- Select the eyedropper tool
- Select the colour of the text you wish to test
- Repeat same steps for background and the Pass/Fail results will be shown on the page
Using Accessibility checker within PowerPoint
PowerPoint also has Accessibility checker built in (accessible by selecting Review > Check Accessibility) to make colour contrast checking easier.
The only caveat to keep in mind when using these types of built-in checkers is that they can sometimes fail to detect the low contrast items with shapes and diagrams. In the screen capture below, on the left we have a slide in PowerPoint with text written directly inside the circle shape and also inside a textbox placed on top of the circle, both with very low colour contrast ratio. PowerPoint’s accessibility checker doesn’t seem to detect either items and incorrectly gives a false-pass on the contrast check, where we can clearly see that it fails the requirements when checked with the WebAIM: Contrast Checker on the right.
So we recommend double checking the colour contrast for shapes and images of text with a contrast checker to ensure that the contrast requirements are met.
Chat with us!
Lastly, we’re currently piloting Slide Design Office Hours for quick and casual chats about all things related to slide design. There is no registration required, just drop in with your slides and get expert tips on the spot!
For further questions or assistance with slide design accessibility, please contact the EdTech Office or book a consultation.