In 1931 the Commission Internationale de lEclairage (CIE) devised a methodology that permits any color that can be seen by the average human eye to be denoted by a pair (x,y) of real numbers each of which is seen between 0 and 1. This pair of numbers is termed the chroma of the color and the graphical representation is called the 1931 CIE Chromaticity diagram.
A Black body radiator is an object which when heated sufficiently produces a light emission whose color is directly related to the temperature. When the temperature versus the chromaticity of the emitted color is plotted on the CIE Chromaticity diagram, the graph is referred to as the Planckian locus or black body locus points on the locus are referred to by their Color Temperatures.
Two standard values of color temperatures of the white point on a video display are important for medical imaging applications. One is 9300 Kelvin with (x,y) coordinates ( 0.285, 0.292) and the other is 6500 Kelvin with (x,y) coordinates of (0.313, 0.329).
Many Color display for the Personal Computer have been set up to approximate a 9300 Kelvin white point. This white level is slightly bluish. This is the most preferred representation for the Grayscale images for Radiologists.
The 6500 Kelvin is also bluish-white but is more like a daylight fluorescent light. Colors for pathology specimens look more realistic when video display system has the value set at 6500 Kelvin.