Color
Color, physical phenomenon of light or visual perception associated with the various wavelengths in the visible portion of the electromagnetic spectrum (see Electromagnetic Radiation ; Spectrum ). As a sensation experienced by humans and some animals, perception of color is a complex neurophysiological process. The methods used for color specification today belong to a technique known as colorimetry and consist of accurate scientific measurements based on the wavelengths of three primary colors. PRIMARY COLORS The human eye does not function like a machine for spectral analysis, and the same color sensation can be produced by different physical stimuli. Thus a mixture of red and green light of the proper intensities appears exactly the same as spectral yellow, although it does not contain light of the wavelengths corresponding to yellow. Any color sensation can be duplicated by mixing varying quantities of red, blue, and green. These colors, therefore, are known as the additive primar...