Highlights

Use color to highlight a specific aspect of the data (e.g. trend lines) or to depict all values without bias.

Color serves two seemingly contrasting purposes in data visualization. It’s used to either draw the reader’s attention to a specific piece of information, or to make all information equally visible. Both uses of color may be implemented in the same plot and we’ve already seen lots of examples, e.g. the regression line in Figure fig-mamm-explain and the semi-transparent dots of the scatter plot in the background.

The challenge to using color appropriately is choosing the right combinations which allow them to fulfill their purpose. To this end, we need to consider the kind of data we’re encoding as color.