Color temperature

Color temperature is the temperature of a blackbody whose emitted color most closely matches a light source. It describes the source’s appearance, not necessarily its physical temperature.

Blackbody radiation: Electromagnetic radiation emitted by an ideal object that absorbs all incident radiation. Its spectrum shifts toward shorter wavelengths as the blackbody heats, creating the temperature-to-color relationship.
White balance: A camera adjustment that makes neutral objects appear neutral under a particular illuminant. Camera white balance often uses an estimated color temperature to compensate for scene lighting.
Physical temperature: A measure of the thermal state of matter, related to the distribution of particle energies. A lamp’s color temperature need not equal the temperature of its components or surroundings.
Planck's law: A formula describing the spectral radiance of an ideal blackbody at thermal equilibrium. It predicts the wavelength distribution underlying blackbody color at each temperature.
Planckian locus: The curve in a chromaticity diagram traced by the colors of blackbody radiation at different temperatures. It maps each blackbody temperature to a chromaticity used to define color temperature.
Daylight (standard illuminant): A family of standard illuminants representing average daylight at specified correlated color temperatures. Daylight references let imaging systems and color measurements use reproducible illumination.
Tint (color science): A green-to-magenta color adjustment used to correct deviations from the Planckian locus. Color temperature alone cannot indicate whether a source lies above or below the locus.
Wien's displacement law: A relation stating that a blackbody’s peak emission wavelength is inversely proportional to its absolute temperature. It summarizes why hotter blackbodies appear bluer, though color depends on the full spectrum.
Correlated color temperature: The temperature of the nearest point on the Planckian locus to a light source’s chromaticity. It extends blackbody-based temperature labels to sources whose colors do not lie on the locus.
Tungsten lighting: Incandescent lighting produced by passing electric current through a tungsten filament. Its warm appearance is commonly associated with a low color-temperature reference in photography.

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