The battle between efficiency and quality in packaging graphics is one that has raged for decades. Flexographers have been conditioned to choose one or the other. Equinox, a technology to reproduce custom spot colors with standard 7-color process, has proven to deliver both.
“It used to be that all flexographic package printing was done with custom spot colors,” recalls Esko’s Product Specialist-Color, Mark Samworth. “Each brand color was reproduced with a custom mixed ink and printed on a separate deck of the press. In the 1970s, 4-color CMYK was added for the reproduction of images. For the first time in flexography, color was being mixed on press instead of in the ink room.”
But even then, printers wondered, “If we can print images with 4-color CMYK, why not print brand colors the same way?” The cost benefits were obvious, but two big obstacles stood in the way. First, the CMYK color gamut wasn’t large enough for most brand colors. Second, flexo did not have the stability required to achieve consistent color throughout the length of a production pressrun.
“The entire value chain—from brand owner through converter— has been well aware of the extreme inefficiencies of the custom spot color workflow for 30 years, but until recently, there has not been an alternative,” Samworth says.
On the Horizon
Advancements in digital prepress, digital plates and flexo presses have made stable process color printing a production reality. However, having stable process colors is only half the battle. The ability to achieve a color gamut capable of reproducing brand colors that package buyers demand was also a requirement.
And so Esko set about investigating ways to print spot colors accurately using seven process colors instead of four. The goal was to mix colors on press instead of in the ink room, in a way that the consumer could not tell the difference when viewed on the supermarket shelf. Samworth notes that the term “fixed ink set printing” may be more descript of the economic benefits than the term “expanded gamut.” It’s about using the same seven colors on every job, eliminating the enormous costs associated with custom mixing in the ink room, custom setup on press and running every item as a separate job. It’s about gaining the efficiencies of a process color workflow without sacrificing quality.
Esko’s solution, a suite of software technologies called Equinox, converts brand colors as well as RGB or CMYK images to 5-, 6- or 7-color process. For its achievements, it has been awarded an FTA 2014 Technical Innovation Award in the prepress graphics category.
Commenting on the award, Samworth reflects, “There’s a lot of great new flexo technology out there. For a committee of industry experts to objectively select Equinox as the most valuable technology of the year is a great compliment to the development team at Esko. Receiving this award will help further the adoption of Equinox in the flexo industry and encourage Esko to continue its large development commitment. That will be good for the flexo industry as whole.”
In developing Equinox, Esko examined how current 4-color management technologies could be applied to 7-color. After studying ways to make 7-color profiles using all combinations of CMYKOGV and ICC formats, the company found it could get more accurate profiles and, therefore, greater color accuracy by using 7-color profiles that consisted of relevant combinations of four colors.
Instead of fingerprinting and profiling all combinations of CMYKOGV, four combinations of four colors are used:
“It was early in the inventive stage that we found these 4-color combinations of seven colors were capable of color accuracy in the range of custom mixed inks, but we didn’t really see the benefits of applying Equinox technology to images until we began testing with a major CPC on real, live jobs,” Samworth explains. “We realized that most package designs today contain photographic images, and how dull and lifeless the CMYK images looked on the 7-color package design. With 7-color gamuts that range an average of 70 percent larger than 4-color gamuts, we knew we had the potential for significant improvements in photographic image quality—we just needed to develop the math to make the conversions.”
Moving from RGB to 7-color was fairly straightforward. But since most packaging images are CMYK, Esko wanted to find a way to convert 4-color CMYK to 7-color in a way that takes advantage of the full 7-color gamut. In researching different algorithms, the team discovered that the “mathematical maximum” gamut expansion looked great on some images, but provided too much on others. Samworth gives as an example an image containing flesh tone and a peach. Both are tan colored and have similar L*a*b* values, but applying the maximum gamut expansion to the peach increased perceived visual quality while applying the maximum gamut expansion to the flesh tone instead decreased perceived visual quality.
After attempting to differentiate between colors based on L*a*b* value, they realized more of what was deemed the “correct” colors was dictated by psychology. “We actually did some research and learned that this phenomena was well understood,” recalls Samworth. “People have preferences on how they want different types of images to be reproduced and these preferences are highly predictable. To oversimplify, people prefer to increase the chroma in an image as high as possible without making it look unnatural.” Although the phenomena of the “preferred reproduction” was well documented, there were no tools to achieve it, particularly when converting a photographic image from 4-color to 7-color.
“Now, through a user friendly interface and a series of curves related to lightness, chroma and hue, a user can get the benefit of truly color managed gamut expansion and be able to selectively discriminate according to color space how much gamut expansion to apply to different subjects,” Samworth says.
Equinox features a Photoshop plugin to convert RGB or CMYK images to 5-, 6- or 7-color. It also features plug ins to the well established products ArtPro and PackEdge, for vector conversion of spot colors. New in 2014 will be the ability to automate the conversion of images and vector graphics in Automation Engine, Esko’s packaging graphics workflow.
Equinox is applied in the prepress department while jobs are being readied for the press. Its expanded color gamut technology works in tandem with Flexographic Image Reproduction Specifications & Tolerances (FIRST) guidelines. The software allows jobs to be printed more economically and more consistently. It also enables “gang” pressruns, or combining multiple jobs into one run. A printer’s savings from gang runs, according to Esko, can eclipse $1 million per press annually.
If any single technology can help flexo increase market share versus other print processes—particularly digital— Samworth believes it is expanded gamut. “Many of the benefits attributed to digital printing have nothing to do with digital printing and are actually benefits of printing with a fixed ink set,” he says. Lots of short run packaging is going digital already and most long runs will remain flexo for the foreseeable future. Expanded gamut—fixed ink set flexo—enables flexo to compete with digital for short to medium runs.
In the battle between efficiency and quality, Equinox improves both. Spot colors print more stably with 7-color Equinox than with custom mixed spot colors. Images look better. Above all, the total economic impact is extreme. For most flexo printers, implementing 7-color process—whether it’s called expanded gamut or fixed ink set printing—is the single largest step they can take to increase profitability. Equinox makes this large step easy. And Samworth says that future development efforts will focus on increasing ease of implementation. “We don’t plan to stop our commitment until we make 7-color process as easy as CMYK.”