C*
Metric Chroma defined in CIELab units. This value may be called as "Saturation"

c
CMC relative tolerance for Chroma.

Calibration
Definitions of calculations of the graduations of a measuring devices;

• With respect to the spectrophotometer, the calibration of factors which will compensate for instrument variables and produce repeatable and accurate measurement results.
• With respect to primary colorant file, the calculation of data to represent colorant optical behavior.

Color Difference Equations
The equation and method to calculate how far of two (or more) samples in color spaces.

• ANLAB Equation
  An apponent color scale for color difference proposed by Nickerson which is based on Adam's Chromatic Value parameters.
• CIELab
  Color Difference equations based upon the CIELab Color Space established by CIE in 1976.
• CMC
  Color Difference equations proposed by the Colour Measurement Comittee of the Society of Dyers and Colourists.
• Hunter Lab
  Color Difference equations based upon the Hunter Lab Color Space devised by Richard S. Hunter in 1942.
• FMC-II
  Color Difference equations based upon CIE Color Space devised by Friele, MacAdam and Chickering in 1943.

Chroma
One of the three terms used in Munsell notation which appox. correlates with the psychological dimension of saturation.

Chromaticity
Color attribute that encompasses Hue and Saturation.

Chromaticity Coordinates
Coordinates x,y,Y used in the location of Hue and Chroma attributes in CIE Color Space.

Color Difference
The magnitude and charater of the difference between two object colors under specified conditions.

Colorimeter
Instrument whichsenses tristimulus values and converts them to chromaticity components of color. It measures color directly by using red, green and blue filters, which correspond to a set of CIE tristimulus values.

Color Temperature
The color temperature of an illuminant is the temperature (in Kelvin degree) of black body which approx. the color of the illuminant.

Colorimetry
A numerical definition of perceived color which encompasses illuminant, sample reflectant or transmission, and visual response of the observer; the science of the quantitative measurement of color.

Color Space
Three dimensional Color Coordinate System which may be used to represent all colors. Some of the common Color Spaces and their respective dimentsions are;

• CIELAB >> L*, a*, b* and L*, C*, H*
• Hunter Lab >> L,a,b
• CIE >> x,y,Y

Color Tolerances
Allowable deviation in coloe from target sample may be expressed in terms of Color Space dimemsions or Color Difference units.

Contrast Ratio
A measurement of opacity, expressed as a percentage. The ratio of the reflectance of a sample over a black substrate to that of the reflectance of the same sample over a white substrate. In general practice, the CIE "Y" is chosen as a measure of reflectance. A contrast ratio of 100% is defined as complete hide (opaque).