Photos courtesy of GMG
Proofs that accurately simulate a printed result—flexographers and their consumer product company (CPC) customers have been asking for them, if not insisting on their development for years.
Rather than focus on color management for commercial print—which typically uses one CMYK ink set, a limited variety of substrates, and relies on International Standards Organization (ISO) or General Requirements for Applications in Commercial Offset Lithography (GRACoL) standards—GMG’s focus was on packaging, which typically requires five-to-eight different spot colors, a wide range of substrates; as well as a vast number of ink channels and print sequences. At issue: predictability of overprints—inks printed on top of each other.
Experts at GMG Color found themselves voicing such observations time and time again, and they often explained, “For a combination of four inks you needed a CMYKIT8.7/4test chart that actually printed 1,617 patches.” Its construction was deemed “costly and time-consuming,” especially given the fact that, the number of patches required to print grew exponentially with each ink.
Eventually, GMG color specialists set out to develop a computer-based tool that can predict and calculate the appearance of any different color combination with a much smaller test chart and much fewer patches. Their objective: “Measure pure single tone ramps of any spot color and predict overprint colors, saving lots of fingerprints and test charts.”
Motivating Force
Members of the team recalled, “One of the most difficult challenges facing a converter is accurately and reliably communicating color between all parties of the supply chain, from the brand manager to the printer.
“In packaging, many jobs require different combinations of inks, substrates, screening, and other variables. A chocolate wrapper might have two browns; fruit juice might have oranges, greens and reds. To understand colors by mixing them, every combination would require a specific test chart with the different combinations.”
Elaborating on such a scenario, they said, “It is costly to go to press with color fingerprint charts, make plates, and spend time testing rather than earning money on a job.” Today, as a result of their research and development efforts, they reported, “You do not have to print combinations of overprints. You can print the single color patches—color control strips—and combine the color and substrate properties in the software.”
The new technology, winner of Flexographic Technical Association’s 2013 Technical Innovation Award, reduces time to market, cuts makeready preparation and expenses, and eliminates 
unnecessary fingerprints. At the same time, it improves the color communication and approval process between all supply chain partners, and verifies color expectations.
For a printer, this has a profound effect on performance. It affords:
- Packaging standardization and shorter production cycles
- Production of promotional, limited time specials
- Faster testing of color and ink combinations that are affected by food safety
- Reduced carbon footprints, due to less time spent on makereadies and materials
Algorithms & Measurements
Consumer product companies (CPCs) have very high color accuracy expectations across printing processes and different converters, according to GMG. “OpenColor creates high-quality multi-color profiles simulating the printing behavior of diverse printing technologies, media types, and screening technologies—if necessary, without use of proprietary, chart based press fingerprinting.”
New spectral modeling algorithms are coupled with spectral ink measurements that analyze the properties of each ink color, as well as the substrate’s colorimetric properties, according to the software developers. This information is applied to a specific printing process (flexo, offset, gravure). Then, process specific information is added (ink rotation, trapping, etc.), and the final press condition is simulated on a proof.
Measurements are centrally saved and categorized according to print variables. This lets operators build an archive of measurements and combine existing measurements to new profiles, whenever a new combination of inks must be profiled.
The profile engine is even able to create a multi-color profile with single step scales of spot colors on the substrate, GMG explained. Accuracy is increased by adding more overprint readings. The system can support up to 15 arbitrary colors in one profile, is offered with standard targets, and is compatible with Hexachrome, Equinox and other multi-color technologies.
The prediction algorithms contained in the software, are said to combine existing color measurement data along with different media and ink order simulations, without printing many patch charts for each combination. It works for reverse printing, used for scratch resistant packaging, as well. Profilesare calculatedon-the-flywhenever a new ink combination must be simulated. Thisprovidesgreater prepressautomation.Color measurement data is centrally available, letting everyone workwith the most recent version of color-critical data.
Diligently Developed
GMG OpenColor was created from five years of scientific research and analysis about the spectral behavior of ink and media. Basically, GMG color scientists sat behind a microscope and analyzed many different print results to determine how screening and dot shapes intersect, and how light is reflected on every surface.
Based on these findings, the GMG color scientists developed the advanced mathematics for OpenColor. The algorithms are based on a sophisticated physical calculation model that considers how many variables affect how light is absorbed and reflected, including the layers of ink; the media; the screening (shape and size of the ink dots); and glossiness of the media. All influence color behavior, as well as the general characteristics of flexo, gravure and offset printing processes. Capturing such data and utilizing it effectively is critical to understanding how the print process behaves on the press and how printing affects color.
Every flexographer knows that a proof is the tool the industry uses to visualize job appearance. OpenColor helps provide the customer with a more reliable proofing process, where one can see what will come off the press before a job is printed, thereby saving both ink and press time; affording quicker approvals and speeding packages to the shelf.
Profile Engine
- High-quality multicolor profiles simulate the printing behavior of diverse printing technologies, media types, and screening technologies
- Spectral modeling algorithms are coupled with spectral ink measurements that analyze the properties of each ink color, as well as the substrate’s colorimetric properties
- Information is applied to a specific printing process (flexo, offset, gravure)
- Final press condition is simulated on a proof