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Paper for IS&T NIP16 Conference, Vancouver, Canada, Oct. 16-20, 2000 (Final manuscript)
CIE Fundamentals for Color Measurements
Optical Technology Division
National Institute of Standards and Technology
Gaithersburg, MD 20899 USA
The paper first overviews the CIE system of
colorimetry, covering CIE 1931 color matching functions,
tristimulus values, the
diagram, the 1976
diagram, and the evolvement of CIELUV and CIELAB
color spaces and color difference formulae.
reviews the measurement of object colors introducing CIE
standard illuminants and the CIE terminology for color and
reflectance measurements, then the measurement of light-
source colors (including displays) with calculation of
correlated color temperature and color rendering indices.
The paper also discusses practical aspects of color
measurements for imaging applications using
spectroreflectometers, spectroradiometers, and tristimulus
colorimeters. Overview is given for calibration and
verification of instruments’ accuracy, spectral irradiance and
reflectance standards (available from national laboratories),
and uncertainty components.
is used with different meanings in
different technologies. To lamp engineers, color refers to a
property of light sources.
To graphics art engineers, color is
a property of an object’s surface (under a given
illumination). In each case, color must be physically
measured in order to record it and reproduce the same color.
The perception of color is a psychophysical phenomenon,
and the measurement of color must be defined in such a way
the results correlate accurately with what the visual
sensation of color is to a normal human observer.
is the science and technology used to quantify
and describe physically the human color perception.
basis for colorimetry was established by
Internationale de l clairage) in 1931
based on visual
experiments. Even though limitations are well recognized,
the CIE system of colorimetry remains the only
internationally agreed metric for color measurement.
the official color-related international standards and
specifications use the CIE System. The CIE system works
well in most cases, but one should know the assumptions
and limitations in visual conditions where the CIE system is
In this paper, the CIE system of colorimetry is
briefly overviewed, and then practical aspects of color
measurements and instruments – spectroreflectometers,
spectroradiometers, and colorimeters – are discussed, with a
focus on the calibration methods and standards. Uncertainty
components and correction for errors are also discussed. For
further details in colorimetry and color science, refer to
official CIE publications
and many other appropriate