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Manual TECHKON SpectroDens
Trapping
With the feature
Trapping
there can be checked, how good two layers of ink which
are printed over each other represent the resulting mixed color.
There are no standard values for the trapping measurement. The values which can
be obtained depend on the printing process and particularly on the type of ink and
paper used. Typical values for standardized print with Paper Class 1 (glossy, coated) are:
C+M > 60 %, M+Y > 72 % and C+Y > 85 %.
SpectroDens offers extended trapping calculation according to Professor Ritz and Fe-
lix Brunner, which ensure a better comparison between C+M, M+Y and C+Y measure-
ments. An alternative determination how well two separate colors overprint can be
checked with a colorimetric function, such as the L*C*h*-feature, where the L*- and
C*-values give the information of the printable gamut.
Three measurements are necessary: Two
measurements on each of the two separate
process colors and finally one measurement
on the resulting overprinted patch.
Here in this example first Cyan and second
Magenta has been measured. The final mea-
surement is done on a blue patch as the
overprint of Cyan and Magenta. The trapping
value is 73.2 %. The higher the value the bet-
ter the overprint of two colors.
Additionally to the trapping value in %
there are the densities for the separate color
patches displayed. The densities are always
displayed with the filter channel of the sec-
ond printed ink; in this case Magenta. This
explains why the density value for the first
printed ink Cyan is so low. SpectroDens will
recognize automatically the order of colors as
they are printed. Switching the first and sec-
ond measurement therefore will lead to the
same result.
K
C
M
Y
SLUR C+M K
C
M
Y
1
80% 40% BAL
2
1. 2. 3.
