When designing, be wary of using colors that are low in saturation because they
are hard to tell apart. A common map technique, for example, is to use a pale blue
for water features and pale yellow for land features. These two colors are a lot harder
for blue–yellow color deficient individuals to tell apart than high‑saturation colors.
Another situation to be on the alert for when designing for red–green color deficient
individuals is using two colors that are the same for all components except green and
red. A blue and a purple, for example, which differ only in their red component, may
appear the same (see Figure 5.17).