Color Contrast

Comparative Visibility of Full Value Color Combinations

These 14 color combinations for lettering were tested using only primary and secondary colors of full intensity and value. Tests for readability at a distance were conducted through various advertisers under the sponsorship of the Outdoor Advertising Association of America (OAAA).

Color Frequencies and Contrast

Like sound waves, light rays have varying wave lengths or frequencies. The lighter the color, the higher the frequency. These wave lengths determine how we perceive color. Some pigments absorb certain light frequencies and reflect others. We see the reflected frequencies as color.
Complementary colors such as red and green are not readily legible. They have similar black and white value, so their wave lengths set up a vibration. Any combination of colors of similar value, even without vibrating, will have low visibility. However, although yellow and purple are complementary colors, they have strong contrast in value and therefore little vibration.