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Mixing and combining red and blue in data visualization
Correcting an Unsuccessful Diverging Color Scheme
In color theory, mixing colors in a painting context differs from combining lights together in a display environment . With painting, pigments are combined together to create another color. In a display context, lights are merged together to produce a different hue. For the specific case of Red and Blue, mixing the two paints together yields Purple. However, Magenta results when Red and Blue lights are blended. Combining Purple and Magenta hues results in Violet in either context. Red and Blue are also used to depict opposing trends in data. In this writing, I discuss how to work with both concepts to create sequential and diverging color schemes for your data visualizations. I show an example where the combination of Red, Blue, and Violet as a diverging color scheme is unsuccessful in color-blind simulator tests. I propose a solution that does pass color deficiency.
A Color Theory Viewpoint of Red and Blue:
Red and Blue are both primary colors in either the traditional Red-Yellow-Blue (RYB) color space or the Red-Green-Blue (RGB) color space for desktop and mobile display devices. Like concepts in music, color harmony is the process of choosing colors that work well together in the composition of an image. This concept is frequently depicted with the use of a Color Wheel, a tool that organizes color hues in a circle to visualize how the hues relate to each other. The color wheels for the RYB and RGB color spaces differ slightly and are shown below.
The RYB color model is called a subtractive color model since when the Red, Yellow, and Blue paints are mixed, the result will be Black. The RGB color model is defined as an additive color model where the combination of Red, Green, and Blue lights produce White light. Examining the Painters’ RYB color wheel and the Display RGB color wheel more closely, it becomes clear that the Blue and Red hues produced with paints are slightly different hues than the Blue and Red lights in the display space. Mixing Blue and Red pigments yields a Purple paint in RYB color space while merging Blue and Red…
