Color Management

Because color-matching problems result from various devices and software using different color spaces, one solution is to have a system that interprets and translates color accurately between devices. A color management system (CMS) compares the color space in which a color was created to the color space in which the same color will be output, and makes the necessary adjustments to represent the color as consistently as possible among different devices.

The following components are integral to a color-managed workflow:
Device-independent color space. To successfully compare different device gamuts and make adjustments, a color management system must use a reference color space—an objective way of defining color. Most CMSs use the internal CIE (Commission International ed’ Eclairage) LAB color model, which exists independently of any device and is large enough to reproduce any color visible to the human eye. For this reason, CIE LAB is considered device-independent.
Color management engine. Different companies have developed various ways to manage color. To provide you with a choice, a color management system lets you choose a color management engine that represents the approach you want to use. Sometimes called the color management module (CMM), the color management engine is the part of the CMS that does the work of reading and translating colors between different color spaces.
Color profiles. The CMS translates colors with the help of color profiles. A profile is a mathematical description of a device’s color space, that is, how the reference CIE values of each color in the color space map to the visual appearance produced by the device. For example, a scanner profile tells a CMS how your scanner “sees” colors so that an image from your scanner can be translated into the CIE color space accurately. From the CIE space, the colors can then be translated accurately again, via another profile, to the color space of an output device. Illustrator uses ICC profiles, a format defined by the International Color Consortium (ICC) as a cross-platform standard.
Rendering intents. No single color translation method can manage color correctly for all types of graphics. For example, a color translation method that preserves correct relationships among colors in a wildlife photograph may alter the colors in a logo containing flat tints of color. Color management engines provide a choice of rendering intents, or translation methods, so that you can apply a method appropriate to a particular graphical element.

What is ICC Profiles?

ICC Profiles
ICC profiles describe the possible range and unique color characteristics of a given device (hardware or software). For instance, if your digital camera oversaturates yellows by 6% (thus, under saturating the opposite of yellow, blue, by the same amount), the ICC profile will state that defect. With that knowledge, the CMS can then pass on to other devices further down the line the instruction to swing the yellow-blue pendulum back 6% into the blue area. Thus, even though your very first step is flawed at creation time, the CMS compensates for the flaw (without actually altering the image content) to produce onscreen and printed color free of the defect and true to the color of the subject of the photo. Even while you work on a flawed image, the CMS will be actively compensating, adjusting the results of your manual editing to account for the actual yellow over saturation—an over saturation that you won’t see because the CMS, running Photoshop and your monitor, have compensated for it to display for you corrected colors. In the plainest English, a CMS does all the hard math for us. Where do these Rosetta stones come from?

Each and every color-handling device renders color slightly differently—even two of the same model. At this moment, for example, I’m using dual monitors. I ordered them from the manufacturer simultaneously, and they both carry the same lot number and date of manufacturer stamped on the back. From this information it’s reasonable to infer that they were made if not one right after the other, then at most only a few units apart. Despite that, they render colors differently. The one to my right shifts grays a shade or two onto the warm side. It also does a better job with midrange cyans and greens than the monitor on my left. I know because I’ve calibrated and profiled them.

Calibrating
Calibrating is the process of getting something as close as possible to its full color potential.
To calibrate your monitor(s) on Mac, use ColorSync in Control Panels. On Windows, it’s Microsoft’s feature-poorer Image Color Management (ICM) user interface. The way to get to and configure ICM has a tendency to change over versions of Windows, so rather than walk you through four or five different methods, the fastest way is to press WIN+F1 on your keyboard and search for the phrase “color management.” Once your monitor is calibrated, you should create an ICC profile for it (or them), which is the last step in both ColorSync and ICM. InDesign and other Creative Suite software will then pick up and use the monitor profile from ColorSync or ICM, compensating for the unique characteristics of your monitor as you work.

Both ColorSync and ICM rely on your eyes to determine color, gamma, and white and black points, but your eyes aren’t reliable color gauges. They can be influenced by ambient conditions like other lights in the vicinity, how long your monitor has been switched on, monitor light reflected off other surfaces, and the unique physical aspects of your eyes themselves. The configuration of rods and cones in our eyes are as unique as our retinal patterns. For instance, 10% of men and 1% of women have some form of color blindness, profound or subtle, and many never even notice it. Calibrations by eye—and the profiles created thereby—should be considered approximations, not accurate determinations of unique monitor color rendering. To get an accurate description of how the monitor interprets color, you need to take the subjective human out of the equation.

A software-backed hardware device that attaches to monitor screens is the best way to profile a monitor (and often calibrate in the same process). That device is a colorimeter. Note that device color characteristics change over time and should be profiled again often (monthly if not weekly).
To measure the color characteristics of a printer—anything from desktop to proof printer to digital press—use a spectrophotometer. This hardware device examines printed output, determining color fidelity on the printed page. If you go to your local Home Depot, you’ll find a spectrophotometer behind the counter in the paint department. Although they often only know it as the “paint matching scanner thing,” the folks at Home Depot use it to extract eight-color tint formulas from paper and other physical objects.

When it comes to profiling a printer, it gets a little more complicated. You see, a printer—inkjet, laser, web press, offset press, everything—lays down ink that is, more or less, the same color across all jobs and production floors. Cyan, magenta, yellow, black, Pantone colors, and all the other inks we use are predictable in their color and, for the most part, identical from one shop to the next. However, ink color is not the only factor when it comes to printed color. Equally important is the color of the substrate, or paper stock, on which ink is printed. Cyan, magenta, yellow, and many pre-mixed spot inks are semitransparent and are therefore tinted by the color of the substrate beneath. Laying down 100% cyan ink coverage on pure, neutral white substrate gives you pure cyan. However, putting down 100% cyan ink coverage on yellowed parchment yields a sea foam green. If you want to see pure cyan atop yellowed parchment, your software has to be told that fact so it can adjust the colors to compensate for the tint of the substrate. Thus, every time you print on a new substrate, you should use a new ICC profile built specifically for that output device and substrate combination.

When you don’t have direct access to the color rendering device—for example, your print provider’s devices or if you vended out your oversized scans—and therefore can’t profile it yourself, ask the service provider for the most up-to-date ICC profile for the relevant device (on the substrate you’ve chosen). ICC profiles are just ASCII files with an .icc (or .icm) extension. They’re easily emailed as attachments. Once you receive them, drop them into the correct system folder:

Mac: /Library/ColorSync/Profiles
Windows: \Windows\system32\spool\drivers\color

InDesign and other color-managed applications and technologies will automatically detect and make available in the Color Settings dialog (see below) profiles stored there, although you may have to restart the applications after installing new profiles. Once the profiles are recognized, you’ll need to actually tell InDesign or whatever application you’re using to use the new profiles.

By telling your creative tools about the color characteristics of your print devices, you can work in software like InDesign confident that what you see onscreen will print fairly close to the same way. Once your creative software knows your monitor, output, and input (digital camera, scanner, etc.) profiles, you will have achieved predictable color and a color-managed workflow.