7-21
IM AQ6373-01EN
Analysis
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App
Index
Explanation
Chromaticity measurement
The COLOR analysis function performs a color analysis of the active trace waveform
using a color matching function, determines the chromaticity coordinates, and displays a
chromaticity diagram.
The color of light is determined by the correlation between the spectral radiance of the
light source and the spectral luminous efficacy of the eye of the person viewing the light.
According to the CIE (international commission on illumination), the spectral responsivity
of the human eye is defined by three color matching functions: x (λ), y (λ), and z (λ). The
outputs when measuring a light source via these light matching functions are expressed
as X, Y, and Z, which are called the
tristimulus values
.
The instrument measures the spectral distribution using a monochromator to determine
the tristimulus values employing JIS Z 8701. The chromaticity coordinates x, y, and z
can be determined from the tristimulus values. There are two color matching functions:
CIE 1931 based on a 2-degree field of view, and CIE 1964 based on a 10-degree field
of view. The instrument uses the color matching function based on the 2-degree field of
view.
Chromaticity diagram
This is a diagram that expresses the characteristics of color through chromaticity
coordinates and spectrum loci.
Chromaticity coordinates
This is the numerical rendering of the characteristics of a light source’s color according
to the spectral luminous efficacy of the human eye. It is determined from the tristimulus
values.
Dominant wavelength
Like the chromaticity coordinates, this is a numerical rendering of the characteristics of
an input optical spectrum’s color according to the spectral luminous efficacy of the human
eye. If a straight line connecting point N (0.333, 0.333) of the chromaticity coordinates of
the achromatic color of a chromaticity diagram and point C of the chromaticity coordinates
of the input optical spectrum is extended, the dominant wavelength is the point at which
the line intersects with the spectrum locus. It is the wavelength that represents the color
of the measured spectrum, and is sometimes called the
main wavelength
.
7.8 Chromaticity coordinate analysis (COLOR analysis)