Cie L*A*B - Techkon SpectroDens Manual

CIE L*a*b*

The previously described measurement functions all were based on densitometry.
Thanks to the spectral performance of SpectroDens it is possible to calculate and
display colorimetric values as well. Measurements in colorimetry modes have the
advantage of an absolute description of color based on characteristic values.
L* = 100
- a*
- b*
L* = 0
Manual TECHKON SpectroDens Chapter 2 – Measurement functions
+ b*
L* = 50
+ a*
The thematic separation between densito-
metric and colorimetric functions is displayed
by a dotted line within the measurement
function window. CIE stands for the interna-
tional color institute Commission Interna-
tionale de l'Eclairage which publishes the
standards for colorimetry.
The most popular color system in the print-
ing industry is the CIE L*a*b* color space.
Every color is precisely described by three
values: The L*-value stands for the luminance
and can have values between 0 (a theoretical,
absolute Black) and 100 (a theoretical, ideal
White).
The a*-value describes the color value on
the Green/Red-axis (- a*: Green, + a*: Red)
and the b*-value the color value on the Blue/
Yellow-axis (- b*: Blue, + b*: Yellow).
Example: Colorimetric L*a*b*-measurement
on a blue sample. The blue color has a lumi-
nance of L = 41,5 and a low portion of Red
(a < 1).
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