Color management is one of the most misunderstood areas
of print, even amongst print professionals. Perhaps
that is because it is not a concise system of predetermined
actions, but is rather a continuum of knowledge and
advisable behaviors intended to help practitioners to
predict (and thereby control) the color of a final printed
piece.
Color management theory is a response to what one might
call the “Babel Effect”— that every
color device (your monitor, your desktop printer, a
professional color proofer, an offset printing machine)
has its own unique way of representing color—its
own color language. As a result, the same image looks
different between one monitor and another, between digital
camera or scanner and monitor, between monitor and inkjet
proofer, between inkjet proofer and platesetter, and
so on. Color management practice is the “Esperanto”
of Color devices—a system whereby images can,
in theory, be represented the same way on every device,
every time.
While much more could be written on color management
than is practical to state here, the following are a
few need to know basics:
1. Color Space: The two primary color
spaces are RGB (Red, Green, Blue) and CMYK (Cyan, Magenta,
Yellow, Black). The RGB space, which allows a larger
color range, is marvelous for reviewing and working
with images on screen. The problem is, process color
printing uses CMYK inks on paper, producing a much smaller
range of color. It is therefore fundamentally important
to evaluate your color based not on how it looks in
RGB space on your monitor, but based on how it will
likely look in CMYK space on your final substrate.
2. Color Standards and Color profiles:
“What is correct color?” is the print industry
complement to the conundrum of “How long is a
piece of string?” International standards like
SWOP (Specifications for Web Offset Publications) and
GRACoL (General Requirements for Applications in Commercial
offset Lithography) are sophisticated and objective
baseline sets of color targets and tolerances around
which cameras, monitors, proofing devices, plate setters
and printing machines can be gauged and calibrated.
While this does not resolve the subjective question
of whether the color you see is “correct”
or not, it goes a long way in determining whether the
color you see on your screen or proof is accurate to
the underlying color benchmarks. In layman’s terms,
it lets you know “which way is up.”
For more on this subject, please visit the following
links:
www.swop.org/resources/Intro_to_SWOP.pdf
http://www.gracol.org/about/index.asp
ICC Profiling is a technique developed by the International
Color Consortium, first initiated by Apple® in the
1990’s. To make sure that each device you use
through the process represents color the same way, one
can identify the Color profile of one device and then
load this profile on another device, allowing it to
convert the image data in such a way that it will be
represented on both devices in the same way.
4. Device Calibration: Device calibration
is the process of adjusting the output of a color device
to a target—a known standard like SWOP. It is
limited by the range of color and the degree of refinement
allowed by your devices, Hence, if you are a professional
designer or photographer, you probably have expensive
scanners, computer monitors and proofing devices as
well as a spectrophotometer and color management software
to calibrate your devices. If not, then to some extent
or another, you are viewing your images through “Magenta-tinted
glasses”. Only when you receive a digital proof
from a machine calibrated to the elected standard will
you know how your images really look.
5. Digital proofing and Soft Proofing: As
the print industry more and more elects to eliminate
the use of intermediary films in the print plate making
process (CTP), digital proofs rather than traditional
“Wet proofs” are used to check color before
printing. The biggest advantage of digital proofing
is that a calibrated proofing device adjusted to a color
target, can provide very close accuracy of how your
color will finally look on press. Soft proofing works
the same way, without the paper. A properly calibrated
monitor and a set color target allow you to see on screen
a near approximation of the final piece. Digital proofing
is not without its pitfalls though. See our head to
head comparison of CTF vs CTP workflow to learn more.
6. Color Management in practice: In your work
with China Printing Solutions, what this means in practice
is that if you are a sophisticated color management
practitioner and want to work with us from the start
to control color, we can provide you with ICC color
profiles and test proofs calibrated to SWOP, GRACoL
or a device profile to gauge and manage color results
from start to finish. If you wish, we may assist you
in retouching photos or adjusting process colors to
help you meet a desired result. If you are not set up
to manage color in this way, the digital proofs we provide
you will be pretty darn close to what you can expect
in the final piece. If that red barn on page 42 turns
out to be kind of orange, better that you know that
at the pre-press stage than when a container of 30,000
pcs shows up at your door.
7. Shortcomings of Color Management:
The tragedy of Color Management Theory is that it is
based on ideal circumstances that don’t really
exist in the World.
A few of the limitations of the process are as follows:
—Images on monitors appear via transmitted light,
images on paper appear via reflected light. Our brains
perceive them slightly differently.
—Image devices have different ranges of color.
While its possible to limit the color range that makes
up an image on a device with a larger range, that’s
a one way street. Meanwhile, colors out of range are
going to be changed to the nearest approximation, which
may in fact be dead wrong.
—Proofing paper is different than printing paper.
There’s not a lot of range of proofing paper...if
we proof on a thick and slick glossy substrate but print
on an absorbent and slightly yellow substrate, it’s
going to look different.
—It’s an imperfect process. Even with great
attention to best practice, Calibration and Color management
are challenging only work “so well” How
close any device can be calibrated to a target depends
on that device, the spectrophotometer, the software,
and the practitioner.
—Images are considered stand alone, but print
in groups. That red barn on page 42 that looked perfect
on screen and on the proof is printing on a form right
above a blue sky on another page. If we allow it to
be the nice red we like, that sky is going to look more
than a little purple. As a result, the art of compromise
prevails...we pull back on the red a bit, resulting
in a good looking sky and barn, if less than the ideal
red.
Why bother at all, you may ask?
Printing remains a blend of art and science, and there
is no such thing as a perfect print job. But the pursuit
of perfection almost always produces far better results
than no effort at all.
Want to know more about color management? Visit this
excellent link:
http://www.idealliance.org/dal/resources/presentations/HutchNYC021005.pdf