The night is dark. The highway is crowded. The only thing in sight are miles of tail lights. And although those points of light mainly serve to agitate the drivers sitting behind them, thanks to the Society of Automotive Engineers’ standard J578, tail lights can also teach an important principle of color management. It’s no accident the red portion of tail lights are within a specific range of colors.
“If you look at tail lights of cars they all look the same because the color of the tail light is measured using CIE-based L*, a*, b* values — that’s how universal the CIE system is for measuring color,” says Jim Rich, president of Rich & Associates, Bethesda, MD, and author of three Adobe PhotoShop books.
CIELAB refers to a standardized three-dimensional color model with coordinates that describe three characteristics of a color — L* representing lightness, a* representing where the color is on the redness-greenness axis, and b* representing the yellowness-blueness axis. It is an objective, device-independent way to define a color. (Device-independent means the color can be defined without the color-rendering capabilities of any specific device, such as a monitor, scanner, or printing press.)
The same L*, a*, b* standard used to make tail lights the familiar color of red is also used to ensure that a picture remains consistent from scanner to monitor to printer and from job to job. Consistency is the goal of color management. But before discussing color management further, it is imperative to first understand the principles of color.
|Profiling software converts RGB values to CMYK values through the CIELAB standard.|
The visible spectrum ranges from wavelengths of 400 nm to 700 nm (one nanometer is one-millionth of a millimeter). The wavelength determines the color perceived. For instance, the longest wavelengths are viewed as red and the shortest, violet. When waves within the visible spectrum hit an object, objects absorb and reflect the waves. The colors we see when we look at an object come from the reflected waves. While both an object and the waves coming from it are necessary components of color, if there isn’t a person looking at an object and detecting the waves, the object has no color.
Color, at its core definition, requires human involvement. And since all humans perceive color differently, color communication becomes very subjective if color isn’t measured and communicated through a universal standard.
Take the example of tail lights. The Society of Automotive Engineers mandates that tail lights be manufactured according to standard J578, which sets an acceptable color range. Without a device-independent standard, getting tail lights to adhere to this regulation would be a difficult task.
|A GretagMacbeth spectrophotometer measuring density blocks.|
Not everyone agrees on the definition of color management. “One of the biggest problems with the adoption of color management is: What does it really mean?” says David Zwang, president of Zwang & Company located in Danbury, CT.
There are generally two schools of thought when it comes to color management. The first view: color management is getting colors to match, regardless of the methods involved. The second view: color management today involves using color science to arrive at consistent color.
William Li, Project Engineer for Creo Inc., Burnaby, BC, Canada, falls in the first camp of opinions. “Most people have come to associate the phrase ‘color management’ quite narrowly with the use of ICC profiles to change color in digital files. Under my definition, on the other hand, people have been managing their color for decades before this, it’s just that the tools they had to manage color with — ink keys on press, film burn charts, etc. — were very different in detail,” he says.
Until recently, color management was based solely on human perception — operators matched color using past experiences and eyesight. This is still an important aspect of color management for some in the printing industry. “Going by the numbers,” as Rich describes the technique, “is where skilled operators use halftone percentages of cyan, magenta, yellow, and black inks or even red, green or blue level values for RGB image files to numerically match specific colors and tones they have learned by looking at previous color proofs.”
Relying on operator expertise is still where color management begins and ends for many printers. This is demonstrated in part by the fact that advanced color management tools are not yet widely used. “According to TrendWatch Graphic Arts, almost 80 percent of printers say they use color management, but only 20 percent own or even use spectrophotometers,” says Zwang.
Most color experts agree color science technology is fundamental to color management, but there is disagreement about whether or not methods grounded in operator ability, such as “going by the numbers,” are viable color management processes at all. While it was the only way to manage color in the past and is still in wide use today, many choose to exclude it from modern day definitions.
According to Don Hutcheson, president of Hutcheson Consulting, Washington, NJ, color management is “any method of reproducing color or matching color that is based more on color science rather than on trial and error.”
As technology continues to develop, color science will become more visible in the world of color management. Color management based on color science involves, along with other tools and methods, using measuring devices. There are three types of measuring instruments: densitometers, colorimeters and spectrophotometers. A densitometer helps determine how much ink is on a substrate and is the most elementary of the tools. Colorimeters and spectrophotometers are used to determine L*, a*, b* values.
Colorimeters mirror the way humans see color by filtering light into red, green and blue regions. While it is useful, the spectrophotometer is the most advanced color measurement tool. “It really sees color in a much more analytical way. It’s more like a fingerprint or a DNA test,” says Iain Pike, worldwide product manager for X-Rite, headquartered in Grandville, MI. Spectrophotometers collect spectral data, which can be transformed into both colorimetric and density data.
“Color measurement is absolutely fundamental to color management but it is only a small part of it. It is a bit like saying is there a difference between inks and a printing press. You cannot print without inks and you cannot do color management without color measurement, but neither is the totality of the subject,” says Tony Johnson, technical secretary for the International Color Consortium, a group dedicated to the standardization and evolution of color management, headquartered in Reston, VA.
Although both schools of thought are respectable, the duration of this article will focus on color management in relation to color science. This is the more modern view of the word, and as such, the least understood.
Calibration and characterization
The color management cycle starts with the original specifications and finishes when the final product is produced. While color management also occurs on press, pre-press is fundamental to the process.
Calibration, whether considered color management itself or a process control that leads to accurate characterization, is an important prepress process. It basically does two things: “First, it defines the optimum settings for that device; and second, it puts it into a stable repeatable position to which you can put it back any time in the future simply by re-calibrating,” says Hutcheson. One of the important functions of calibration is using it to control dot gain. To ensure accuracy, calibrating should be done before characterization.
“The key thing is to keep devices calibrated,” says Rich of Rich & Associates. “Once the devices are in a known state, you can get things optimized.”
Characterization, also known as profiling, is another important aspect of color management. Profiles have been standardized by the International Color Consortium.
“Think of the ICC profile as a dictionary to translate between languages. The dictionary doesn’t speak French, but it will help you to translate from English to French to enable you yourself to speak in French. The accuracy of translation, of course, is a vital factor in the utility of the dictionary,” says Li of Creo Inc. Profiles are created for scanners, monitors and printers. Once a profile of a device is created, profiling software converts device-dependent values to a device-independent standard, such as CIELAB.
“A color profile is essentially a giant look-up table of numbers from the device’s color space (e.g. RGB or CMYK) into a device independent color space (e.g. CIELAB),” says Mark Samworth, vice president of technology for Artwork Systems Inc., in Bristol, PA.
“All profiles are made with software, and sometimes hardware, that first print or display, (or in the case of a scanner, provide an original target), a series of color patches that are of known values. The software then reads the resulting colors and creates a profile,” says Brian Lawler, a graphic arts consultant in San Luis Obispo, CA.
“Profiles are the heart of color management. Without good profiles, color management can be worse than doing things the old way,” says Hutcheson.
There are myriad other processes under the umbrella of color management, but calibration and characterization are often the starting points. While color management can be tightly controlled within a pre-press environment, when color management extends into press operations there are an entirely new set of variables to consider.
“It involves a lot of cooperation from your vendors to make sure they’re in control,” says David Bruce, Graphics Manager of Info Label, Mechanicville, NY. It is possible for inks and substrates, even when coming from the same company and consisting of the same materials, to vary enough that color differences are noticeable to the human eye.
The investment vs. the payoff
Even with the latest technologies, color management is not perfect. Spectrophotometers measure L*, a*, b* colors slightly different. Colors created using RGB and converted to CMYK cannot always produce identical color matches, even with the best profiles. And even if the final color is a complete match with the original, it isn’t a guarantee the customer will like it.
“The biggest challenge in color management is meeting the customer’s expectation because even though our system says the color is accurate to what they want, it’s still personal — everyone sees color differently,” says Tony Lewandowski, general manager at Graphic Solutions Inc., located in Burr Ridge, IL.
No matter how objective color becomes through the use of devices and processes, there will always be some measure of subjectivity. But it doesn’t mean printers should throw up their hands and give up. Color management has come a long way, even from five years ago, and there are a lot of benefits to utilizing it.
“The need [to manage color] has always been there. As tools have become more available, then we use those tools,” says Mark Barnard, vice president of Trinity Graphics USA, Sarasota, FL. Trinity Graphics USA, color separators and platemakers for the flexo industry, started color managing in the modern sense of the word around 1998. Barnard estimates that a week was spent for training, and that costs to implement the system were around $3,000.
Consistency is the main goal of color management. “If we can see on our monitors what we are getting on our proofs, then at least we are consistent,” says Barnard. “On the inside of our little world, we’re going to get the same thing every time.”
Pike of X-Rite sees additional benefits. “The reason people do color management isn’t because they want to. People don’t want to make a profile... What they really want is to get good color out of their processes and to meet customer’s needs,” he says. Pike also lists saving money through less waste and more production on press, and an improvement in the quality of printing as further benefits of color management.
Other printers who have implemented color management technology agree. “If we had every dollar that we wasted [prior to color management] in press makeready or downtime we’d be able to revamp our prepress with that savings. Color management takes so much subjectivity out,” says Bruce of Info Label. Info Label places high priority on color management. Bruce estimates that $8,000 to $10,000 has been invested in color management. He says the payoff is worth the investment.
Customers are often the driving force to implementing a color management program. “The whole point is to make what the customer wants,” says Yates Downes, graphics director for Spectrum Label Corporation, Hayward, CA. “We have to communicate.” Spectrum Label switched to a modern color management system approximately a year ago.
Utilizing color management technology has proven advantageous to printers in other ways. “It offers great advantages in proofing and in any workflows where it is desirable to produce the same color by different processes. It also permits more flexibility in printing — when printing the same label in multiple sites it is not necessary for all printers to work to the same specification,” says Johnson of the International Color Consortium.
Is it necessary?
“It is not going as quickly and as smoothly as I’d like, but it’s a big project,” says Downes. “Everybody has to buy into it. There’s a lot of issues involved in making it work properly.” Given the relatively high level of investment and the fact color management is often a misunderstood process, printers may wonder if it is necessary.
Grant it, beautiful work can be done without color management. But when it comes down to it, an aesthetically pleasing label is not the only thing important to customers.
“You go to the trade shows and everyone has a nice piece of eye candy, but nobody is showing you the printed label against a contract proof,” says Bruce.
|The GretagMacbeth color target TC6.02 contains color patches, later measured to determine the gamut of colors possible on a printing device. From this data, an ICC profile is built.|
“I want [the package] to be visually consistent,” says Sward, “In my end of the business, we want it as close and as tight as we can.”
In some niches, good color management is vital. “In our markets, its worth the expense, it’s worth the time,” says Andre Michaud, graphic director of Dow Industries, located in Wilmington, MA. “It makes us much more effective in what we do with much less frustration.” Dow Industries focuses on health and beauty, and personal care products markets. The company’s investment has been significant. “In money, the whole thing is attached to our digital proofing system. We’ve probably spent $80,000 total. The investment in time is ongoing,” says Michaud.
However, not every printer prints labels that end up on store shelves, showrooms or on health and beauty counters. The needs of the customer, and the necessity of color management technology, are dictated in part by the industry. “Our industrial-based customers are less likely to complain about color. Customers who use our product for product identification are very, very critical of color,” says Lewandowski of Graphic Solutions.
The complexity of the jobs printed also needs consideration when deciding if modern color management tools are necessary. “If the printer prints almost entirely one type of ink on one type of stock, they’d be better off investing money in process control and just hiring someone to come in and create the profile for them rather than try to build up and maintain expertise in-house. On the other hand, if a large amount of custom work will be done, or if it’s a multi-site operation, it might be worthwhile to invest in building up in-house color capability,” says Li of Creo Inc.
Color management, no matter how it’s defined, is finding an increased audience that promises to grow as technology advances. While some may consider it a luxury to monitor color through the use of tools, others feel it is a necessity. “Before you could explain away why your color wasn’t quite right. Now, you can’t,” says Lewandowski.