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Choosing Colors for Accessibility

Earlier this week, Ryan sleeper wrote a very informative post about improving the design of your data visualizations with your color choices. He touched on how straying from the built-in Tableau color palettes can give your dashboards a more custom feel, solidify the theme, and effect the appeal of the dashboard to your audience. But there is also another time that you should be cognizant of your color choices: when you need to make your dashboard accessible to folks who are colorblind. The U.S. National Library of Medicine estimates that 1 out of every 10 men have some form of color blindness. If you are using color to code important data, you should think about using color palettes that accessible to color blind people.

Tableau has a built-in palette of 10 colors that translate well to colorblind people. But what about when you need something with more options? James Davenport of If We Assume turned me on to a color scheme dubbed “Cubehelix”.

This is a color scheme that is generated programmatically and always de-saturates to black and white. This makes it not only a great option for those who are color blind, but also for charts that will eventually be printed in black and white. For example, take a look at the dashboard below. The top is the original in a standard Blue-Orange diverging palette and the bottom is in Cubehelix. If we de-saturate this image, it becomes much harder to tell what is happening in the original map. The areas in the south with high diabetes rates look to be at equal values with areas like Colorado who have some of the lowest rates of diabetes. But, you can see that Cubehelix de-saturates perfectly.

James was provided me with the hexcodes for his go-to Cubehelix palettes. I created a preferences.tps file that you can use to install these custom palettes on your computer. You can find the file, as well as the code for creating Cubehelix palettes for yourself here.

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