HunterLab SpectraTrend HT, Руководство пользователя

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SpectraTrend HT User’s Guide 3.2
96
n
Y
Y
100 L
=
n
n n
a
Y
Y
Y
Y
-
X
X
K a
=
n
n n
b
Y
Y
Z
Z
-
X
X
K b
=
where:
X, Y, and Z are CIE tristimulus values
X
n
, Y
n
, and Z
n
are tristimulus values of the standard illuminant as listed in ASTM E308 with Y
n
always equal to 100.00 (normalized)
K
a
and K
b
are chromaticity coefficients for the illuminant used (see ASTM E308).
Illuminant A represents incandescent (tungsten) lamp light with an approximate color
temperature of 2854K.
Illuminant C represents average, or north sky, daylight with a correlated color temperature of
approximately 6770K.
Illuminant D50 represents daylight with a correlated color temperature of approximately 5000K.
Illuminant D55 represents daylight with a correlated color temperature of approximately 5500K.
Illuminant D65 represents daylight with a correlated color temperature of approximately 6500K.
D75 represents daylight with a correlated color temperature of approximately 7500K.
Illuminants F2, F7, and F11 represent light from a cool white fluorescent source.
The CIE 1976 L*a*b* scale is recommended by the Commission Internationale de l’Eclairage (CIE). It is a
simplified cube root version of the Adams-Nickerson space produced by plotting the quantities of
L*a*b*in rectangular coordinates.
The relationship between the CIE L*a*b* scale and the CIE XYZ scale for any illuminant referenced in
ASTM E308 is as follows:
16 -
Y
Y
f 116 = * L
n






a * = 500 f
X
X
- f
Y
Y
n n


















b * = 200 f
Y
Y
- f
Z
Z
n n

















