Software can be used to set ink restrictions for each colour.
Customizing a profile
When the standard steps do not achieve the expected colour results, the next option is to develop a custom profile. By taking the time to do so with the specific device and production environment in mind, signmakers can ensure the best possible colour gamut is attained.
A custom profile is developed for the precise resolution and speed of the combination of printer, ink and media being used. A canned profile may not support these desired settings.
The process of creating a custom profile involves setting primary or per-channel ink restrictions for each colour. The production department’s specific environmental conditions may dictate using more or less ink than with a canned profile. This step is very important. With some practice, colour managers will learn how to create the maximum colour gamut for a device under a given set of printing parameters.
After the primary ink restrictions are set, the next parameter to define is linearization. This is the process of optimizing control over the variables involved in printing, so as to ensure predictable results. With many RIPs, linearization is what enables G7 calibration to occur.
It can be tricky to determine where specifically to insert G7 calibration into the RIP software for wide-format inkjet printing. For one thing, there is no standard way of doing it. For another, the RIP’s own algorithms for the colour management workflow may generate calibrations that are lacking in image consistency.
So, some practice will be needed. The payoff will come when the grey-balanced and known ‘good’ print condition is achieved, as then a common visual appearance will be seen across many graphics despite their different variables, from fabrics to rigid substrates, from dye sublimation to ultraviolet-curable (UV-curable) inks and from small roll-fed printers to the largest flatbed presses.
Jim Raffel and Shelby Sapusek are co-founders of ColorCasters, a colour management consulting and training company. Raffel is a certified G7 expert and Sapusek is a certified digital colour professional. This article is based on a seminar they presented in October at the 2017 Specialty Graphic Imaging Association (SGIA) Expo in New Orleans, La. For more information, visit www.colorcasters.com and www.sgia.org.
