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FLEXO Magazine : May 2013
Experts at GMG Color found themselves voicing such ob- servations time and time again, and they often explained, “For a combination of four inks you needed a CMYK IT8.7/4 test 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 com- puter-based tool that can predict and calculate the appear- ance of any different color combination with a much smaller test chart and much fewer patches. Their objective: “Mea- sure pure single tone ramps of any spot color and predict over- print 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 com- municating 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 choco- late 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 report- ed, “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 As- sociation’s 2013 Technical Innovation Award, reduces time to market, cuts makeready preparation and expenses, and elim- inates 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 af- fected 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 differ- ent 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 measure- ments 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 dif- ferent media and ink order simulations, without printing many patch charts for each combination. It works for reverse print- ing, used for scratch resistant packaging, as well. Profiles are calculated on-the-fly whenever a new ink combination must be simulated. This provides greater prepress automation. Color measurement data is centrally available, letting everyone work with 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 micro- scope and analyzed many different print results to determine how screening and dot shapes intersect, and how light is reflected on every surface. www.flexography.org may 2013 FLEXO 51 Start with single step scales... to get precise prediction of all color combinations.