Trapping - Techkon SpectroDens Manual

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. In the Basic version
of SpectroDens the trapping calculation is carried out according to the formula of
Preucil.
1
K C M Y SLUR C+M
1. 2. 3.
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 %. The SpectroDens models of the Advanced-
and Premium-class offer extended trapping calculation according to Professor Ritz
and Felix Brunner, which ensure a better comparison between C+M, M+Y and C+Y
measurements. 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.
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2
K C M Y 80% 40% BAL
Manual TECHKON SpectroDens Chapter 2 – Measurement functions
There have to be made three measurements
in total: 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 which re-
sembles the overprint of Cyan and Magenta.
The trapping value is 65 %. The higher the
value the better 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
second 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
second measurement therefore will lead to
the same result.