What is Correlated Colour Temperature

When the chromaticity point of the light source is not on the blackbody track and the chromaticity of the light source is closest to that of the blackbody at a certain temperature, the absolute temperature of the blackbody is the relevant color temperature of the light source, which is referred to as the correlated color temperature for short. The unit is Kelvin (K).

The longitude and latitude on the map represent the location of the city, and the (x, y) coordinate values on the color coordinate map represent the location of a light color. Look at the figure below, (0.1, 0.8) this position is pure green, (0.7, 0.25) this position is pure red. The middle part is basically white light. This "degree of white" cannot be described in words, so there is the concept of "color temperature".

The light emitted by tungsten bulb at different temperatures is represented as a line on the color coordinate diagram, which is called "blackbody trajectory", abbreviated as BBL, also known as "Planck curve". The light color emitted by blackbody radiation looks "normal white light" to our human eyes. Once the color coordinates of the light source deviate from this curve, we think it is "color biased".

No matter what we do with our earliest tungsten bulb, its light color can only fall on this line representing cold and warm white light (the thick black line in the figure). We call the light color at different positions on this line "color temperature". Now with the development of science and technology, the color of white light we make does not necessarily fall on this line. We can only find a "nearest" point and read out the color temperature of this point, which is called his "correlated color temperature". Now you know? Do not say that as like as two peas, 150K, even if the two lights are the same as CCT, the light and color may be very different. Enlarge the "isotherm" of 3000K:

It's not enough to just say the color temperature. Even if everyone is 3000K, it may be reddish or greenish. "