Color Management 101 - Monitor Calibration
Color management, even of the simplest sort, may not be a ball, but it's the only way to WYSIWYG color.
by: Chris Murphy
All of us who produce print documents want our onscreen
color to be consistent and trustworthy. Yet most
of us don't want to practice color management, which
can seem like a dreaded homework assignment.
However, the reward of that homework, better
onscreen color, is more accurate color on press,
which means happier clients and a happier you.
In this article, I'll demystify certain elements of
color management and suggest helpful tools that
don't require a PhD. I can't promise you'll end up
feeling that color management is akin to recess, but at
least you'll have a study buddy.
How Red Is Red?
Your computer, and the Creative Suite applications,
can't provide the most accurate color without knowing
which colors your monitor is displaying. That is, when
you specify an object as 100% red (often called "255
red"), exactly what shade of red do you see on your
monitor? Every monitor displays it a little differently.
Defining that shade of red and all other colors your
monitor displays is called characterizing or building
a profile. You can also calibrate a monitor, which is
forces a monitor to behave consistently over time with
respect to its color of white, brightness, and tonality.
The tool for both of these tasks is a color measurement
device called a colorimeter. I'll discuss
three mid-range entry-level devices later in the section
"Colorimeters in Action."
Why Can't All Monitors Display the Same Colors?
There are several technological reasons for the
wide variation in monitor colors. Makers of displays
don't always stick to standards, such as sRGB. Some
affordable wide-gamut displays easily exceed the
gamut of sRGB, while most laptop displays have
smaller gamuts than sRGB.
There are also two categories of monitors, each
of which handles color differently: CRTs and LCDs.
CRTs aren't manufactured anymore, but they're still
on many desks. If you have one, it's probably time to
replace it.
Within the LCD market, there are two backlighting
technologies that affect how colors display: CCFL and LED.
What's a Backlight?
A backlight is the light source for any LCD, and it's
essentially what you're changing the intensity of when
you adjust the brightness control. The brightness of
the display affects how bright black and white are. The
difference between black and white luminance is called
dynamic range, or contrast ratio.
The point of any kind of calibration and profiling
system is to approximate the dynamic range of print.
There's no point in looking vastly better than a proof or
press sheet. When your monitor's brightness is set too
high, its contrast ratio is much greater than print. That
makes layouts onscreen look much better (have more
"pop") than prints and proofs.
When your monitor's brightness is set too low, shadow
detail won't be visible onscreen but will be on prints and
proofs. And there's a point at which it's really too low,
and then the color science of all of this color management
stuff doesn't work correctly. So it's necessary to get
the backlight intensity in the ballpark of reasonable.
CCFL has been around for a while, so the colors it
emits are fairly consistent among manufacturers. This
is not the case with the newcomer, LED backlighting.
It promises greater stability and more sensitive
environmental qualities (no mercury). However, LED
backlighting is so new that some measurement
devices can't correctly calibrate LED-backlit displays.
For a few monitor recommendations, see "My Favorite Monitors" below.
My Favorite Monitors
High-end professional displays do cost more than the
displays you'll find on the remainder shelves of your local
electronics store. However, the prices have dropped in
recent years, and the quality really is much higher. If a
more accurate monitor means your jobs are more accurate
when printed, you may find the price worth paying.
When you're looking for a complete end-to-end color management
solution, something you know works, is
worth the money, and is a prerequisite for serious softproofing
and color-critical use, a closed-loop solution is
the best way to go. Prices for high-end professional displays
have dropped recently, and the quality really is much
higher. I like the NEC SpectraView and Eizo ColorEdge
monitors, which come with their own color-management
software for calibrating and profiling the display. I'm particularly
fond of NEC's recent offerings driven by the SpectraView
II Color Calibration Solution, which includes colorimeter
and software thoroughly tested to work very well
with their displays. It's hard to beat the price/performance
of the $560 Multisync P221W entry-level professional 22"
wide-gamut display. And their high-end 2690 and 3090
series SpectraView II displays, which also closely approach
the Adobe RGB (1998) color gamut, yet remain within the
grasp of mortals to purchase, are personal favorites.
Designers often wonder why a monitor can't
calibrate itself and provide its own custom profile. As
it turns out, there is something that could help, called
EDID, or Extended Display Identification Data. It's a
standardized method for displays to announce their
capabilities—such as their resolutions, and specific
measured colors of their red, green, and blue primaries.
If the color information in a display's EDID correlates
reasonably well to actual display behavior (that is, if
the monitor is telling the truth), we might not even
need to calibrate and profile them. For example, the
Mac OS automatically asks for EDID from any display
when you plug it in and builds a display profile from
that information on the fly. For example, the profile
built by the Mac OS from EDID for my 23" Apple
Cinema Display performed comparably to the profiles
produced by third-party colorimeters I tried out (see
"Colorimeters in Action" below).
For various practical manufacturing reasons, the
EDID won't exactly correlate to your specific display,
but if manufacturers could put a little more effort into
this, it would likely make this process good enough for
most designers.
Unfortunately, there are two problems with EDID:
First, there's no way to know if a monitor's EDID
information is correct. And second, Windows users
must track down software to build an ICC profile based
on EDID information, as it's not created automatically
by the operating system.
Colorimeters in Action
Colorimeters, those measurement devices that define
what colors your monitor displays, range in price from
low to high. They're bundled with software that talks to
the colorimeter and your display to calibrate and then
build the ICC profile. This is why you'll find the same
colorimeter at different prices—the price depends on the features in the software. I'll focus here on entrylevel
packages that are low to mid-range in cost.
I tried out four products using a sample image
that contained high key, low key, neutrals, saturated
colors with fine detail, and multiple skin tones. I tested
each product on two monitors: a 23" Apple Cinema
Display and a fourth-generation MacBook Pro 15" LED
laptop. On the CCFL-based Cinema Display, all of the
colorimeters produced fairly similar and acceptable
results. There were no immediately obvious visual
differences in profile quality.
But when testing with the MacBook Pro laptop,
which uses LED backlighting, I found noticeable
visual discrepancies among all of the products. It may
be that none of these colorimeters work well with
LED displays. They may require an entirely different
category of instrumentation: a spectroradiometer,
such as the Eye One Pro or the device used in
ColorMunki Design and ColorMunki Photo.
The $129
Huey Pro from Pantone is so
inexpensive that I was suspicious of its sensor accuracy.
However, while its resulting tone reproduction curve
may not be 100% correct, it isn't objectionable visually.
The Huey Pro's ambient light compensation didn't
work as I expected. I tested it with extremely low
ambient light and with rather high ambient light, but
there was no difference in the two calibrations and
profile Huey created in those two different situations.
The $176
X-Rite i1Display LT is on the opposite
end of the options spectrum. It includes the Eye
One Display 2 colorimeter, which has been around
for some time and is a pretty decent colorimeter
for the price. Its default behavior doesn't help
set the brightness correctly, or flag the user of
unacceptably low brightness. Its advanced mode
is more accommodating but assumes you know
what settings to choose. The "Perform ambient light
check" does check ambient light but doesn't use
that information to suggest a more appropriate
brightness setting. And Leopard lovers beware:
X-Rite's web site states that its software is not
officially tested or supported
on Mac OS X 10.5 (Leopard).
Pantone's $149
Colormunki Create includes
a sensor based on the Eye
One Display 2. It's a piece
of cake to use because there
are no options: not for color
temperature, tone response,
or brightness. The lack of
assistance in setting brightness
is an unfortunate miss. You may
find Colormunki Create useful
if you like its features that create, manage, search,
and share color palettes.
As I mentioned earlier,
we could use help getting
the display brightness
setting established at
something other than
improper, and ideally at
something reasonable. Only
one product I tested does
this somewhat well: Datacolor's
$249
Spyder3Elite. This includes a new 7-sensor
colorimeter, the Spyder3, which the company says
performs correctly with a wider range of display
technologies. It makes a reasonable estimation of
ambient brightness and
corresponding suggestion
for display white luminance
(brightness setting).
With a particularly bright
Apple Cinema Display, the
Spyder3Elite software
proceeded with calibration
and at the end determined
my display was too bright.
It was the only software
I tested to do so. But instead of suggesting the
obvious—reducing the brightness of the display to
achieve the recommended white luminance—the
Spyder3Elite software suggested I increase the
brightness of the room I was in.
The software is very thorough,
involving quite a bit of interaction on
the part of the user. Even the default
path presents too much information,
tries to educate the user too much,
and yet doesn't perform ambient
light compensation by default to
make better recommendations off
the bat. I'd like a shorter path. Those
caveats aside, the Spyder3Elite comes
closest to the feature and performance
characteristics I expect in a professional
tool.
Although I didn't test the $169
Spyder3Pro package, which also
Left: The Huey Pro includes the same Spyder3 colorimeter
and has the same features as I tested in the
Spyder3Elite, I'd expect similar results. I recommend
Spyder3Elite if you need its additional features,
including support for calibrating and profiling
projectors, and for arbitrary white point, which comes
in handy if you want to match white points among
multiple displays.
Why Don't They Just Call It White?
One of the biggest problems with color management
in general, and monitor calibration in particular, is its
obscure terminology: D50, D65, 5000K, gamma 2.2,
gamma 1.8, 6500K, blah, blah, blah. Why in the world
are we still using words developed by color scientists?
One important part of making your monitor more
accurate is defining what it should display for the
color white. I wish color-management hardware and
software developers would give us a slider with which
to choose the color of white. Designers understand
that there are cool whites and warm whites, and
that the objective is to choose a white that roughly
corresponds to paper white.
But since that simple slider doesn't exist, here's
a little cheat sheet: D65 or 6500K are cool white. As
that number goes down toward D50 or 5000K, we
experience warm white.
The best white on which to standardize depends
on your environment and the papers you use. If you
work in a low ambient brightness on magazine-type
printing, 5000K is grand. If you tend to be in a brighter
environment, and/or you work with higher quality,
brighter white paper stocks, 6500K may be more to
your liking.
Liking?! This Is About Liking Something?!
Yes, absolutely. Color management is as much art as
science and therefore doesn't always offer a technical
answer. And when you're more at home in an art class
than a science lab, that may actually be comforting.
Chris Murphy is the founder of Color Remedies, a color management
training and consulting firm. He is a co-author of Real World Color Management, 2nd Edition.
More on
InDesign Magazine. Each issue gives you tips, techniques, and time-savers by an all-star cast of industry experts.