Color Blindness and Data Visualizations
Resources To Help Enhance Accessibility for Persons with Color Blindness
If you’ve created a data visualization, chances are you’ve taken some time to consider the colors making up your visualization. But have you ever stopped to think that maybe not everyone can fully appreciate and enjoy that beautiful visualization you’ve spent so much time poring into?
Color blindness — something that primarily affects men — comes in several variations with red-green color blindness affecting between 5 and 10 percent of all men. Red-green color blindness is when the viewer has difficulty distinguishing between the colors red and green. Blue-yellow color blindness is the difficulty telling the difference between blues and greens and also between reds and yellows (link). This type is much less common than red-green but is still more common than complete color blindness where the viewer cannot see color at all (link).
So what can a Data Visualization creator do to make visualizations more accessible to a wider audience — especially if you don’t even know where to begin? Fear not! There are several outstanding resources to help examine the colors you’ve selected.
First, a quick google search for ‘color blind tests’ will bring up plenty of resources to see how color blindness — especially red-green — is assessed and a variety of testing images. Most of the color blindness testing images you find will be taken directly from or based on the Ishihara test named after its creator University of Tokyo professor Shinobu Ishihara (link). An outstanding series of examples and descriptions can be found on the webeyeclinic.com webpage.
Second, a resource that allows you to upload an image of your choosing and then manipulate the settings based on type of color blindness you’d like to simulate is Coblis or the Color Blindness Simulator found on color-blindness.com. Below is what you can expect when you go to upload an image to run through the color blindness checker. You can select for which type of color blindness you’d like to simulate (options in grey box). This image is set to the default or how an image will look for someone who does not experience any form of color blindness.
After adjusting the settings to show what the image would like for individuals with a type of red-green color blindness, you can see how the image has changed below. This should give some insight to those who are not colorblind what the image would look like to someone with color blindness.
To examine individual colors in-depth, you can use the “Color Picker” option found on the coolers.com website. After selecting a color, you will see your choice and its corresponding Hex value. In the case of the selected color below, Spanish Red, the hex code is #E50F28.
After you’ve chosen a color to examine, a “Blindness simulator” gives an overview of how those with the varying types of colorblindness will perceive that color. Those with Protanopia and Deuternopia, 1.3 and 1.2 percent of men, respectively, will see this shade of red as a shade of dark yellow
Lastly, if you create maps, colorbrewer2.org will allow you to preview color schemes. The site also has an option to select for colorblind safe color schemes. This will allow you to see color schemes that are accessible to those with colorblindness.
So there you have it! A quick introduction to a handful of tools that can be used to make your own data visualizations accessible to a wide range of people — especially those with colorblindness.
