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Correlated color temperature
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Correlated color temperature
Correlated color temperature (CCT, Tcp) refers to the "temperature of a Planckian radiator whose perceived color most closely resembles that of a given stimulus at the same brightness and under specified viewing conditions". The SI unit is the Kelvin (K).
Black-body radiators are the reference by which the whiteness of light sources is judged. A black body is characterized by its temperature and emits light of a specific hue, which is referred to as color temperature. In practice, light sources that approximate Planckian radiators, such as certain fluorescent or high-intensity discharge lamps, are assessed based on their CCT, which is the temperature of a Planckian radiator whose color most closely resembles that of the light source. For light sources that do not follow the Planckian distribution, aligning them with a black body is not straightforward; thus, the concept of CCT is extended to represent these sources as accurately as possible on a one-dimensional color temperature scale, where "as accurately as possible" is determined within the framework of an objective color space.
The notion of using Planckian radiators as a yardstick against which to judge other light sources is not new. In 1923, writing about "grading of illuminants with reference to quality of color ... the temperature of the source as an index of the quality of color", Priest essentially described CCT as we understand it today, going so far as to use the term "apparent color temperature", and astutely recognized three cases:
Several important developments occurred in 1931. In chronological order:
These developments paved the way for the development of new chromaticity spaces that are more suited to estimating correlated color temperatures and chromaticity differences. Bridging the concepts of color difference and color temperature, Priest made the observation that the eye is sensitive to constant differences in "reciprocal" temperature:
A difference of one micro-reciprocal-degree (μrd) is fairly representative of the doubtfully perceptible difference under the most favorable conditions of observation.
Priest proposed to use "the scale of temperature as a scale for arranging the chromaticities of the several illuminants in a serial order". Over the next few years, Judd published three more significant papers:
The first verified the findings of Priest, Davis, and Judd, with a paper on sensitivity to change in color temperature.
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Correlated color temperature AI simulator
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Correlated color temperature
Correlated color temperature (CCT, Tcp) refers to the "temperature of a Planckian radiator whose perceived color most closely resembles that of a given stimulus at the same brightness and under specified viewing conditions". The SI unit is the Kelvin (K).
Black-body radiators are the reference by which the whiteness of light sources is judged. A black body is characterized by its temperature and emits light of a specific hue, which is referred to as color temperature. In practice, light sources that approximate Planckian radiators, such as certain fluorescent or high-intensity discharge lamps, are assessed based on their CCT, which is the temperature of a Planckian radiator whose color most closely resembles that of the light source. For light sources that do not follow the Planckian distribution, aligning them with a black body is not straightforward; thus, the concept of CCT is extended to represent these sources as accurately as possible on a one-dimensional color temperature scale, where "as accurately as possible" is determined within the framework of an objective color space.
The notion of using Planckian radiators as a yardstick against which to judge other light sources is not new. In 1923, writing about "grading of illuminants with reference to quality of color ... the temperature of the source as an index of the quality of color", Priest essentially described CCT as we understand it today, going so far as to use the term "apparent color temperature", and astutely recognized three cases:
Several important developments occurred in 1931. In chronological order:
These developments paved the way for the development of new chromaticity spaces that are more suited to estimating correlated color temperatures and chromaticity differences. Bridging the concepts of color difference and color temperature, Priest made the observation that the eye is sensitive to constant differences in "reciprocal" temperature:
A difference of one micro-reciprocal-degree (μrd) is fairly representative of the doubtfully perceptible difference under the most favorable conditions of observation.
Priest proposed to use "the scale of temperature as a scale for arranging the chromaticities of the several illuminants in a serial order". Over the next few years, Judd published three more significant papers:
The first verified the findings of Priest, Davis, and Judd, with a paper on sensitivity to change in color temperature.