where [bar.x]([lambda]), [bar.y]([lambda]), and [bar.z]([lambda])) are the tristimulus values
of the monochromatic stimuli and k is a constant.
The tristimulus value
Y corresponds to the luminance of a color.
These devices measure tristimulus values
according to CIE illuminant and observer conditions.
The second type called compensation approach reinserts metameric black spectrum to compensate for the loss of spectral details caused by the colorimetric tristimulus values
. Derhak and Rosen  had proposed an ICS called LabPQR with six dimensions.
at wavelength [lambda] of CIE color system  are
The simulations of colors are accomplished by calculating the tristimulus values
X, Y, and Z using the following equations:
CAMs rely on tristimulus values
as the primary input, in addition to adapting conditions and other related criteria.
The Commission International de L'Eclairage (CIE), an organization devoted to standardization in areas such as color and appearance, defined in 1931 a standards light source, developed a standard observer, and enable the calculation of tristimulus values
, which represent how the human visual system responds to a given color.
Drawdowns are made of the paint, and the Y tristimulus values
are measured using a spectrophotometer.
The amounts of the red, green, and blue lights required to match each of the spectral colors are called tristimulus values
. Unfortunately, all colors could not be matched with the set of red, green, and blue lights used in the experiment.
Where L*, a* and b* represent, lightness, red-green, and yellow-blue coordinate respectively; X, Y, Z are the CIE XYZ tristimulus values
of the sample; [X.sub.n], [Y.sub.n], [Z.sub.n] are the CIE XYZ tristimulus values
of the reference white point.
The basic colorimetric characterization of the CRT monitor can be represented as a combination of two parts: the tone reproduction curves (TRCs) for each channel, and the transformation matrix from linearized RGB to tristimulus values