Primary Colors

Section Overview:

The human eye is sensitive to a narrow band of electromagnetic radiation that lies in the wavelength range between 400 and 700 nanometers, commonly known as the visible light spectrum, which is the only source of color. When combined, all of the wavelengths present in visible light, about a third of the total spectral distribution that successfully passes through the Earth's atmosphere, form colorless white light that can be refracted and dispersed into its component colors by means of a prism. The colors red, green, and blue are classically considered the primary colors because they are fundamental to human vision. Light is perceived as white by humans when all three cone cell types are simultaneously stimulated by equal amounts of red, green, and blue light.

The complementary colors (cyan, yellow, and magenta) are also commonly referred to as the primary subtractive colors because each can be formed by subtracting one of the primary additives (red, green, and blue) from white light. For example, yellow light is observed when all blue light is removed from white light, magenta forms when green is removed, and cyan is produced when red is removed. The color observed by subtracting a primary color from white light results because the brain adds together the colors that are left to produce the respective complementary or subtractive color.

Review Articles

Introduction to Primary Colors

Pigments and dyes are responsible for most of the color humans see in the real world. Eyes, skin, and hair contain natural protein pigments that reflect the colors visualized in the people around us. Books, magazines, signs, and billboards are printed with colored inks that create colors through the process of color subtraction. In a similar manner, automobiles, airplanes, houses, and other buildings are coated with paints containing a variety of pigments. The concept of color subtraction is responsible for most of the color produced by the objects just described.

Interactive Tutorials

Contributing Authors

Kenneth R. Spring - Scientific Consultant, Lusby, Maryland, 20657.

Matthew Parry-Hill, Robert T. Sutton and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.