There is a misconception that people who are color blind cannot see color at all. There is a small percentage of the population that proves this true, those who have a monochromatic vision. However, the majority of people considered color deficient can see colors. They have difficulty differentiating between colors. Red and green being the hardest for them to distinguish.
How do You Design Dashboards for the Color Blind?
It is important to keep the color deficient in mind when creating data visualizations as approximately 1 in 12 men and 1 in 200 women have this condition.
- When designing a scatter plot, for instance, make the dots larger, space them out or use a wide range of intensities.
- When creating a geo regional map data visualization, use various shades of one color. There is a good representation of this technique from the BI-NOTES blog, shown in the following figure.
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What Colors do the Color Blind See?
The images below depict the differences between what a red-green color deficient person (right image) would see and what everyone else sees (left image). Notice that the red was changed to green and the blue sky took on a purple hue. The green trees have lost some of their brightness.
The following figure shows the same differences but for data visualization. If color-deficient people were to read the pie chart on the right, they would more than likely not read the information correctly as the red and green blend. They almost appear to be almost the same brown color.
But watch what happens when we apply a monochromatic color scheme. While the colors have changed slightly, the shading is consistent in both visuals. Both pie charts would work well!
Tips for Designing with the Color Deficient in Mind
Good design practices would ensure you take all of the population into consideration when creating data visualizations. An easy way to do this is to use a tool like ColorBrewer.org for selecting color deficient safe palettes.
If you are creating your own, to avoid color deficient pitfalls, here are some considerations:
- Use a standard color palette that is color-deficient friendly
Having a standardized palette set up is a sure way to avoid colors that may prove difficult or frustrating to the color deficient. - Know the combinations
Some colors are harder for the color deficient to differentiate. Avoiding color combinations like red and green, light green and yellow, brown and green. - Use monochrome colors
Distinguishing between colors can be difficult, using various shades of one color is a safe way to avoid issues when designing with the color deficient in mind. Differences in hue, saturation and brightness can be used to your advantage as color blind people can still perceive contrast.
When creating effective data visualizations make sure you think about all of the audiences you are trying to reach. Your goal should be to have clear and concise communications that clarify the data for all.