Color Management: What it is and what it isn't
In a theoretically perfect Color Managed world, a photographer captures a scene and
by checking a few boxes in Photoshop, the scene is perfectly reproduced on a computer screen,
in a magazine, in a coffee table book and on the Internet.
In the real world, Color Management is a tool that helps skilled and experienced people produce
reasonably accurate and consistent color with a minimum of time and materials wasted. Color
Management is not a perfect, idiot-proof system that allows you to turn off your judgment or
send off files to a printer or client with your eyes closed.
Where does Color Management "happen"? Or where do you "turn on" Color Management? In today"s
world, Color Management is integrated into your computer's operating system, software
applications, RIP's and printer drivers. As a result, it is virtually impossible to "turn off"
Color Management. Therefore, learning to use Color Management to get the results you want is an
inescapable fact of digital imaging.
Color Management in a Prepress Production Environment
At BowHaus, we've scanned tens of thousands of film originals (35mm, 120, 4x5 and larger),
prints and artwork. Many of our scans end up on a four-color press and eventually in a book,
magazine or brochure. By profiling our scanners, monitors and SWOP proofing systems, we can
guarantee our clients accurate results whether the press is five minutes away or an ocean away.
What follows is a brief overview of Color Management and some of the tools it offers you.
The Real World
To understand the solution, let's look at the problem. What we "see" is what we believe to be
the Real World. The sky, trees, people, and this piece of paper you hold in your hands. Color
is the perception of different wavelengths and frequencies of the light as it is reflected off
different surfaces of objects in the Real World. Perception is individual and somewhat
subjective. I cannot see through your eyes or process the information with your brain.
Therefore, how do I know if my "apple red" is the same as your "apple red"? That is a question
not easily answered, but in 1931 a series of experiments culminated in the CIE color space that
mathematically quantified and diagrammed the human perception of color based on an "average
This diagram is a visual representation of the CIE color space. The horse-shoe shaped color
area is the range of colors visible to the human eye.
The CIE color space mathematical model makes it possible for us to reference specific colors
using numerical values. In other words, by using the notation developed for the CIE color
space, two people can remotely discuss color in an accurate and objective way. Using a
spectrophotometer, we can "read" the light waves reflected from a color swatch and translate
the Real World into a series of numbers (usually LAB which has evolved from the original 1931
Seeing a color and reproducing that color on a printing press or computer monitor are two
different matters. The Real World has a diversity of light, shadow and color that cannot be
absolutely reproduced on a piece of paper. The Gamut (or portion of visible color that a device
or color space can reproduce) of a printed page is much smaller than what the human eye can see.
The three white triangles are the gamuts of three common RGB color spaces (Wide Gamut, Adobe
1998 and sRGB) superimposed over the CIE diagram of visible colors. As you can see, they are a
subset of what we can see. The black hexagon is the gamut of SWOP four-color printing.
When a scene from the Real World is photographed, it is compressed into a smaller gamut. This
is true whether the scene is photographed on film or digitally. When that photograph reaches
the print stage, it is compressed once again into an even smaller gamut. This process is
destructive by nature, but we can manage the process and define the compromises we"re willing to
make. This is the essence of Color Management, maintaining the essence of an image or integrity
of a color as it traverses from monitor to monitor and one output device to another.
Characterizing Devices and Media with ICC Profiles
Each brand of monitor, scanner, printer, paper, etc. has unique characteristics. In order for
you to maintain the integrity of an image across these different devices and media, we need to
give Photoshop (or whatever application you might use) detailed information about the Gamut and
behavior of each device and media you use. This is what an ICC Profile does. ICC is an acronym
for International Color Consortium.
At BowHaus, our Crosfield Drum scanners are "profiled" by scanning in a standardized film or
print target using standardized scanner settings. The resulting image file is then "read in" by
Color Management Profiling software that compares the scanned data with readings that were
taken from the target using a precise measuring device like a spectrophotometer. The profiling
software creates an ICC "scanner profile" that quantifies the Gamut and specific behavior of
our scanner using the standardized settings. For example, if the scanned image is lighter than
the target, the ICC scanner profile compensates by telling an output device to print or display
the image darker! Which leads us to the monitor profile.
Calibrating monitors using ICC Profiles and Color Management ensures that what we see is going
to be close to what we get. Keeping your monitors calibrated should be part of your routine
maintenance. At BowHaus, we use a variety of monitors and also a variety of software for
calibration. We know that monitors have limitations, and they will never absolutely display
how the final printed piece will appear. Therefore, we treat monitors as an approximation and
also pay close attention to the actual RGB or CMYK values of the file. In the days before
industry wide acceptance of Color Management, skilled scanner operators and digital retouchers
learned how to predict final color based on "reading the numbers".
Next, is the output device and media profile. A monitor is also an "output device", but we are
referring to printers and film recorders. At BowHaus we use Canon, Epson and HP inkjet printers for
small to wide format 60" posters and banners. We also produce Exhibition prints for museums and
galleries. All of our printers and media are profiled and linearized (calibrated) to ensure
consistent results. A print on glossy paper will reasonably match one on canvas, etc.
For SWOP Certified prepress proofing, we use both the Onyx and EFI RIP systems and inkjet
printers. SWOP is an acronym for Specifications for Web Offset Publications. These systems use
device and media profiles, printed test targets and calibration/linearization to ensure that
proofs are accurate.
Assigning and Converting with ICC Profiles
Profiles are like the name tags that convention attendees wear. Your name tag announces who
you are and possibly where you are from, to the hundreds or thousands of other convention
attendees. An ICC Profile gives Photoshop (or other application) detailed color and gamut
information about how an image should be displayed on a monitor and how to print it or convert
it from one colorspace to another, as you would in an RGB to CMYK conversion for four-color
If you mistakenly wear someone else"s name tag, you will be mistakenly identified as that
person. The consequences may range from amusing to worse, but they will be inaccurate in
any case. The same is true if you "tag" or "embed" an image with the wrong ICC Profile.
For example, BowHaus Drum scans are tagged with an ICC Profile that is unique. If you
simply "assign" another profile to one of our drum scans, you will "tag" it with inaccurate
information. The actual image data in the scan will remain the same (the RGB values) but the
scan will probably appear display differently on your monitor.
When you "convert" from one color space to another (Adobe 98 to sRGB, or to CMYK), you are
interpolating and altering the data. This is a critical difference between "assigning" and
"converting". You can assign and reassign an image with different ICC Profiles all day long
without interpolating the data and degrading it. Conversions, on the other hand, do involve
"transforming" the data and multiple conversions will degrade the image and possibly cause
posterization and banding.
Color Management offers you tools and guidelines for the accurate reproduction of your images
and artwork. In a color critical production environment like BowHaus, we use Color Management
PLUS a heavy dose of operator skill and experience.
In the end, our clients (and their clients) are interested in the final result: the book,
publication, display print or fine art print. The Color Management software, RIP"s, ICC
Profiles and monitors that we use, are just part of the process.