G7 is the color control methodology that achieves color similarity across all print processes. The method balances the four primary process printing colors, CMYK and their three overprints RGB (the 7 in G7) to achieve neutral grey (the G in G7) in a raster image. This methodology was created in 2006 by Don Hutcheson and used primarily by the offset lithography printing process at that time.

In 2008, Nazdar Consulting Services introduced the G7 methodology to the screen and wide format graphic ink jet printing processes as the best way to achieve a common appearance in images when printed on different substrates, using different printing processes. This was a big departure from the existing printing specifications (SNAP, GRACoL, and SWOP) which were specific to the offset printing process on a certain grade of paper.

“The G7 methodology is not a print specification as it does not prescribe how to achieve a result, just the result, which in this case is neutral grey balance in the quarter to three quarter tonal areas of an image and a shared neutral appearance,” said Bruce Ridge, director technical services at Nazdar Ink Technologies. “There are two other levels of G7 conformity that can be achieved, Targeted and Color space.

“The focus on the grey balance in the quarter to three quarter tonal areas allows flexibility in substrate and ink deviations. This is critical to the screen and ink jet printing processes where the substrate white point can vary tremendously, and the ink hues may vary from the traditional hue targets originally set by offset inks.

“The Direct to Garment process of Inkjet printing directly to T-Shirts brings this area of printing in line with all the other processes that reproduce full color images using subtractive color inks,” Ridge noted. “The work at Nazdar demonstrates that three different DTG printers can all achieve a G7 qualified print.”