Under the Desktop: Making Time for Color Profiling

David Morgenstern

Most of us know that color calibration is good for us — like bran. Some of us may have even incorporated profiling into one or more parts of our color workflow. But how often do we need to check its goodness? Is it daily, like the proverbial apple that keeps the doctor away? Once a week? Monthly? Or whenever?

That was the question posed by reader Hans Andriese, an Amsterdam-based “DTP warrior” following my recent column that described my experience with GretagMacbeth’s Eye-One Pro and Eye-One Match color calibration package. He wondered exactly when one should profile their monitor, scanner or printer. And how long should that process take?

Of course, the glib response would be: It all depends. But that’s no answer.

A Time to Calibrate Color
The basic rule of thumb would be to calibrate whenever there’s some change with a component of your color workflow. Some of these “changes” can be significant, while others are easily overlooked.

According to GretagMacbeth application engineer Paul Hultgren, scanners should be calibrated when the bulb is swapped out. However, the lifespan of bulbs can be difficult to find — I have yet to see the figure clearly listed on spec sheets. A call to the technical support department for my long-in-the-tooth scanner revealed that its fluorescent bulb lasts up to 4,000 hours, really not all that long when you consider the many minutes involved for its prescan and fine-scan routines.

In addition, Hultgren advised that a printer will need a new profile whenever you replace an ink cartridge or use a new type of paper. And the monitor should be calibrated “as often as possible.”

However, the vagaries of color hardware may produce a more complicated schedule, according to Karl Lang, a color-imaging consultant based in Madison, Wis.

“Scanners are notorious for calibration problems — it’s called light bulbs. They age and they do it in weird ways,” he said. “As scanner bulbs age they not only become less bright, but their output spectrum changes. This means you will need to reprofile the device. How often in this case depends on the type of light source and how much you use it. Some drum scanner halogen sources can exhibit this problem all of a sudden after a certain amount of use.”

In addition to the simple changes of inks and papers, environmental factors can shift colors on hardcopy output. For example, toner-based printers such as color laser printers are particularly susceptible to humidity and temperature, Lang said.

He added that each printing technology has its own issues. He pointed to color changes from aging heads on inkjet printers, and differences as paper stock ages.

“The water content of paper can take a week to stabilize after being moved from one place to another. If it is used during this time it will produce differing results every day,” Lang said. “Some fine art shops calibrate the printers and do a profile before every run. Then they monitor for any color shift during the run. If one occurs they stop, recalibrate the device, and continue.”

Lang recommended that monitors be profiled every two weeks, although a month should suffice for most of us. “As you can see a monitor may be the most stable part of the system — or not.”

Establish a Profile
Notice how Lang makes a distinction between calibrate and profile? This points to an interesting difference in terminology between folks working on the print and prepress sides of the fence. Or those deeply into the mystery that is color science.

On the shop floor, calibration adjusts a device to produce “consistent density of colorant for any given value,” Lang observed. So if we ask a press to lay down 50 percent cyan, it should give us 50 percent cyan.

On the other hand, a profile describes how the primaries mix on a device, often modeled in a 3D space. My colleague Bruce Fraser offers an excellent description of the difference in his color management tutorial.

Lang said it’s often easier for operators to create a profile and then return the press to that previously profiled state during a job. However, that practice assumes that everything stays constant. “If we change paper or ink, the spectral mixing changes and we need to reprofile,” he advised.

So when discussing your color management situation with hardcopy mavens or color consultants, be sure that you’re both talking the same dialect of shoptalk.

Practice Makes Perfect (for Color Calibration)
So on to the second question: How long does it take to calibrate a color workflow? This requires testing each of your devices, at the minimum the monitor, a scanner, and a printer. The time will depend on your particular hardware setup as well as your dexterity in manipulating the profiling equipment. And if you have several monitors or printers, each will need its own color profile. That extra time can add up.

As you can see from my experience, the pile of pieces that comes out of an Eye-One kit could rival a box of Lego pieces. There’s the sensor, a target, adapters for different types of monitors, and plastic guides to help the sensor read the target or printouts (see below). So, it can take some time to gain familiarity with the apparatus and the software. But I found that once I made a half-dozen round trips, it was no problem.

In addition, expect your first pass with the equipment to take extra time — beyond the simple unfamiliarity with the process. For example, calibrating a scanner requires the line-by-line reading of the target. Thankfully, that task must be done only once.

The worst part of monitor profiling is fiddling with the on-screen display. Once that is accomplished, and the monitor is close to the mark, subsequent profiling took a short while effort, perhaps five or so minutes with practice.

After the initial testing of the target, the scanner process was straightforward. Most of the time is taken up with the scan itself. I would budget 10 to 15 minutes, depending on your scanner.

Finally, the printer profile will always be a pain, since it involves running the sensor over a printout. It should take about 10 to 15 minutes, depending again on the speed of the printer.

Have I made this process sound too troublesome? I hope not.

There’s a Jewish saying that sheds some light on the subject: “In time, even a bear can learn to dance.” Calibrating your color devices may be a bear at times, but its benefits could make your workflow boogie.