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Why colormanagement?
Every input or output device interprets colors in a
different way. This can be compared with the diffe-
rences in color perception between human beings,
as everyone has a different color perception and
„thinks" colors different. This is because we all differ
in respect of social, cultural and even physical deve-
lopment.
In contrast to the human being, we are able to adjust
any device to behave exactly like or at least close to
a standard. Colormanagement and calibration are
the key technologies to achieve a streamlined color
reproduction.
The display is a vital part in this workflow as it is
used for both, the artist´s work and the color judge-
ment. In an ideal world, the display should be able
to simulate what is later printed by the printer and
shows the colors of the digital camera or scanner
the same way as these devices have recognized the
color. All this is only possible if a description of every
device is available - the color profile or ICC-profile.
Working spaces (standardized color environments)
make sure that colors can be transformed from one
device to another.
Environmental light
The human eye is heavily influenced by environ-
mental issues in the way that the surrounding light
changes the perception of colors. Thus, wrong
or insufficient environmental lighting is one of the
most problematic issues upon comparing softproofs
on a display with prints. The tonal response of a
print always depends on the light that is used to illu-
minate the viewing area. As lighting is crucial, meta-
meric effects will occur. The color rendering (and our
perception) will be different from the original. A red
could easily tend to be orange, or a blue looks much
less saturated just because of different light sources.
To ease the color communication, ISO 12647, ISO
12646 and 3664 define D50 as the standard lighting
for judging colors and proofs.
Companies like Just, GTI or VeriWide supply D50
light sources for proofing and press environments.
However, other 5.000K tubes (designed for plants for
example) or full-spectrum bulbs will most likely not
match the D50 standard and should not be used.
Four times the same image, but four times with a different color
interpretation, because four different devices are used with
colormanagement and calibration.
INFO
ISO 3664 defines the requirement for the environmental light-
ing in the graphic industry:
The light source must match the D50 standard and needs a
rendering index (precision) of at least 90%. The light inten-
sity should match 2000 Lux (+/- 500) for press rooms and
450 Lux (approx. 140cd/m2) for prepress.
For a display for proof/print comparison, ISO 3664 and 12646
(Proofing Displays) define a working luminance for the display
of 120cd/m2 to 160cd/m2. A viewing booth therefore needs a
light intensity of 377 Lux to 503 Lux.
Different light creates different color rendering.
Introduction
7
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