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What Is Correlated Color Temperature (CCT)?


Everyone should be able to see the data tested. It is the correlated color temperature(CCT), not 
the color temperature. Is there a difference between them? Of course, there are.
The color temperature of a light source is the temperature of an ideal black-body radiator that 
radiates light of comparable color to that of the light source.
In other words, it can only be called the color temperature when it falls on the black body 
radiation line.

black-body-radiation-line

Correlated color temperature and color coordinate conversion formula:
T=-437n3+3601n2-6861n+5514.31,n=(x-0.3320)/(y-0.1858)
T (Color Temperature)
N(coefficient)
X,Y (Color coordinates)

From the formula and definition:
1. The color temperature and color coordinates are one-to-many relationships, and the same 
color temperature has different XY values;
2. The same color temperature produces different color senses.
3. The two points in Figure AB below are the same color temperature, but they show 
completely different colors.


It means that the light from the light source, which is emitted from the black body radiation at 
3000K, has been deviated, but 3000K can only be described on this line. Then this happens:


▲ One color is greenish, and the other color is reddish. Although they are different from the 
human eye, both of them are called 3000K.
It can be concluded that the correlated color temperature is an interval, and the color 
temperature value in this interval fluctuates within a range.
Perhaps many people will be confused, and there are many XY combinations of the same color 
temperature, what color temperature and coordinates are in line with solid-state lighting and 
human eye sensory comfort? How can it be solved?
This is necessary to have our protagonist: SDCM (Standard Deviation of Color Matching)
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