User guide

i1iSis Optical Brightener Compensation (OBC) Module - User Guide
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The information from both measurements is used by the OBC Module to correct for the optical
brightening agents in the substrate. As the level of correction must be adjusted to the intensity of
the effect of the optical brightening agents in a real-world viewing situation, the amount of UV light
in the viewing condition must be assessed as an additional step. Following the measurement process
with the i1iSis, the OBC Module then creates an individual gray evaluation test chart suitable for your
printing condition and your substrate using different corrective measures for the various amounts of
UV light present. The Gray Evaluation Chart is then printed on the same printer using both the same
substrate and same printer driver settings as used for the CMYK or RGB test chart printed earlier in
the process. Once the ink has dried, the individual patches in the Gray Evaluation Chart need to be
visually compared against the OBC Gray Standards in typical viewing condition used for hardcopy
proof evaluation (e.g. a viewing booth or on the control panel of a printing press). The OBC Module
comes with two sets of OBC Gray Standards - glossy and matte, each containing four different gray
levels. Depending on the surface properties of the substrate, either the glossy or the matte set of Gray
Standards is to be used.
The best match between the Gray Standard and the Gray Evaluation Chart will be achieved in the
fields A-C (no or little UV in the viewing condition), D-M (medium UV level in the viewing condition)
and N-S (high UV level in the viewing condition) contingent on the amount of UV light the is present
under the viewing conditions. Please note that some viewing booths have a UVcut filter applied to
the illuminants so results may always end up in fields A-C regardless the amount of optical brighten-
ing agents in your substrate.
The visually-perceptible difference between the various fields on the Gray Evaluation Chart is depen-
dent on the amount of OBAs in the substrate. Where low amounts of OBAs exist, the visual difference
is marginal, making it perhaps difficult to find the right patch. In such a case the strength of the
correction is also marginal so the accuracy of the match is of a lesser importance. In this situation,
the evaluation of the darker gray patches may not be necessary; while they might improve the quality
of the match, an assessment remains difficult for low amounts of OBAs in the substrates or ink films
with a high UV absorption.
If the OBC Module detects no OBAs in a substrate you will be asked to skip the evaluation process as
there won’t be any difference between a NoFilter and a UVcut filter measurement and the assess-
ment of the UV amount of the viewing condition becomes unnecessary. After the visual evaluation of
the UV effect of the viewing condition, a compensated measurement data file is generated and saved
to be used with your profiling application (ProfileMaker 5 or MonacoPROFILER).
Fig.1: Differences between conventional NoFilter (Green) or UVcut Filter (Red)
workflow and the new Optical Brightener Compensation (blue).