Spectral Data: The most complete and precise means of describing a color, by specifying the amount of each wavelength that the sample reflects. Typically, spectral data records the amount of reflected light in 10-nanometer or 20-nanometer bands.
Spectral Power Distribution: The amount of light a light source produces at each wavelength.
Spectrophotometer: An instrument that measures the amount of light a color sample reflects or transmits at each wavelength, producing spectral data.
Standard Illuminant: See CIE Standard Illuminants.
Standard Observer: See CIE Standard Observer.
Subtractive Primaries: Cyan, magenta, and yellow. Used to create reflective color. Cyan absorbs (subtracts) all red light, reflecting blue and green. Magenta absorbs all green light, reflecting blue and red. Yellow absorbs all blue light, reflecting red and green.
Tristimulus: The practice of specifying or creating colors using three stimuli. These may be additive (RGB) or subtractive (CMY) primary colorants; three attributes such as Lightness, Chroma, and Hue; or three purely synthetic mathematical constructs, as with CIE XYZ (1931) or CIELAB.
Tristimulus Data: The three values used to define or create a color, such as Red 255, Green 0, Blue 0. Tristimulus values alone do not define a color unambiguously: The illuminant (light source) must also be defined. In the case of device-dependent tristimulus values such as monitor RGB, the primaries must also be defined in a device-independent system such as CIE XYZ or CIELAB. Tristimulus values can always be computed from spectral data, but spectral data cannot be inferred from tristumulus values.
Visible Spectrum: The portion of the electromagnetic spectrum with wavelengths between 380 and 720 nanometers. Wavelengths in this range provoke the sense of color when they impinge on the photoreceptors in the human retina. The shorter wavelengths within this range produce blue and violet sensations; the longer wavelengths produce orange and red sensations.
Yellow: One of the subtractive primary colors. Yellow absorbs all blue light, reflecting red and green.
This article was last modified on July 11, 2023
This article was first published on August 16, 2005
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