Geospatial Response

Accessibile Conversations


About once a month I receive a message from my accessibility coordinator at work asking to help out, or answer an accessibility question pertaining to cartography.

The latest question posed was related to cartographic color contrast on interactive, and printed maps. A designer tested out some color schemes against an approved color contrast tool, where all of the schemes failed the check.

Instead of trying to answer the question electronically, the accessibility coordinator and I met in person to discuss the problem, see the color contrast checker tool in action, and discuss the details together.

We discussed the problem, determined who was effected, and the next steps. Below are some of our discussions and findings:

What’s the problem?

ColorBrewer’s color schemes fail against Web Content Accessibility Guidelines (WCAG) 2.0’s color contrast ratio. One of the tools used to verify the contrast ratio was WebAIM’s Color Contrast Checker.

Figure 1. WebAIM color contrast checker

Got it. So, who is affected?

This was the main focus during our discussions, and it’s where we started asking a wide range of questions. Does color contrast on maps even make sense?

This was one of the questions we couldn’t answer, and it led to a few others, such as:

  1. If you have a choropleth map, without any labels on it (Figure 2), is color contrast an issue for any audiences?
Figure 2. ColorBrewer choropleth map
  1. If you have an interactive map with a basemap (Figure 3), how do you consider color contrast with the colors of the basemap, transparencies (if applicable), and colors of the data displayed?
Figure 3. Interactive map with choropleth data over a basemap.

So let’s assume audiences aren’t effected… What does it look like now?

Using some of the tools I use to check my maps, both interactive, and print (on computer monitors, and printed on paper) we determined the colors checked out with visually impaired audiences. We already knew this from past meetings, but we confirmed it together to be sure.

Our concluding thoughts

After the testing, we determined, in most circumstances, if the cartographer isn’t layering color on top of color, WebAIM’s color contrast checker doesn’t do us much good.

The color contrast checker tool’s goal is to verify a foreground and background color have enough contrast between one another. The checker is not made to work with adjacent colors. There are other, more useful tools, to check on adjacent colors on a webpage, or in our case maps.

Final thoughts

So, why am I sharing this story with you? Because accessibility is hard, and not all answers are yes and/or no.

Accessibility is determined by people, which is why it can be so difficult. But the payoff for making an experience the same for all users makes it all worth it!

In the last year, I’ve learned three awesome takeaways when it comes to accessibility:

  1. Have discussions: When it comes to accessibility, there isn’t always a clear cut answer. My accessibility coordinator and I frequently sit down and talk about issues as they come up. Do we always come up with the answer(s)? No. Many times we come up with more questions than we started with. That’s the nature of accessibility!
  1. Ask questions: Accessibility is about people. If any components of your work fail an accessibility check, that doesn’t always mean you have to change anything. Always ask: Who does this effect, and why would it effect them? If you can’t answer either question, is it always necessary to build around them? Sometimes the standard rules won’t apply, and we could be overthinking the process, and forgetting about the experience.
  1. Accessibility is awesome. Accessibility inspires innovation, and makes it possible to deliver similar experiences to all audiences. I mean, that’s pretty cool, right? 🙂