Reflections on the Uses and Available Choices of Categorical Colorschemes

Abstract

Categorical colorschemes must respect a number of criteria-mainly, they need to incorporate a number of easily distinguishable colors, and they need to avoid giving to the reader the impression that the colors in the visualization have particular relationships. Crafting these palettes requires careful attention to the distribution of colors; thus, for a long time, visualization designers have been relying on a limited choice of readily available palettes. Although such palettes have been proven practical and functional, our own experience with designing visualizations had us struggle repeatedly with the limited choice, the feeling of repetitiveness in seeing the same colors in visualization papers, and a number of other limitations that we discuss in the paper. In this document, we discuss some properties of the most common categorical colorschemes, and propose a method to generate new palettes that are comparable in properties to the existing ones.