Although everyone discriminates between colors differently, designers can make certain color choices to increase visual accessibility. Color contrasts must sometimes be exaggerated to ensure that even those with color deficiencies are able to distinguish between different hues and values.

Artists and designers choose colors carefully, sometimes altering the natural color of things to incite a specific reaction. Local color refers to the actual and expected hue, whereas occult color means a hue that is unexpected and abnormal for a specific object or scene.

The rods and cones in our eyes work differently under different light conditions. Cones do not function well at night so rods take over to help distinguish forms when our ability to separate between colors is lost.

Color perceptions vary between species. Some animals, like dogs, have a heightened nocturnal vision in order to compensate for their low color vision.

Simultaneous color contrast and optical illusions can be explained scientifically as the rods and cones in our eyes tend to fatigue when we focus on a certain color and we consequently create that color’s complementary in our minds. This is why when we close our eyes for a while on a sunny day, our vision shifts to a cool blue when we reopen them. The warm, orange-ish light we see behind our illuminated eyelids causes a negative afterimage and our brain produces oranges complement, blue, creating a successive contrast.

Color contrast plays an important role in the design of exhibitions and trade shows. Designers employ these contrasts to help visitors navigate or to signal areas of important content.

It is interesting to note that color theories were proposed across a wide range of disciplines, including painting, textile manufacturing, meteorology, physics, psychology, etc. The effects and interactions of color are visible in every aspect of life.

Johannes Itten seems to make contradictory statements about color harmony, or at least Designer’s Color Manual presents them as such. Page 44 says, “Itten believed that color harmony is entirely subjective” while also suggesting that he taught his students that “[harmony] is achieved only when colors are mixed . . . to produce grey.” Is this not an objective means of arriving at a harmonious color pairing? So… is finding color harmony a subjective task, or is it more methodical like finding musical harmony?

Why is Itten’s color star shaped the way it is? It seems natural to arrange hues in a circle, as the movement between them is indefinite. But why do the spaces representing darker colors get smaller as they move outward? I think this might be to suggest a balance of color proportions as their value changes. But as Goethe’s model of relative color strengths suggests, this reduction in size would not happen at the same rate between different hues. Munsell’s color tree addresses a similar problem by acknowledging the limits of saturation to which some hues are confined. Interestingly, Munsell’s color tree is also subject to some debate regarding his subjective rather than scientific choice or colors represented in his model.