What is a G7 Master?
The IDEAlliance G7 Master Program is a qualification program that identifies those creatives, premedia and printing companies who have been trained to proof or print to G7 Neutral Print Density Curves and can meet print buyer requirements to produce proofs or printed output conforming to the metrics that reliably render brand images across print locations and different printing types.. The qualification mark means that the printer uses the modern technology based on colorimetry, and employ G7 process controls. G7 Masters bear the IDEAlliance seal of approval. Attaining G7 Master status is a competitive goal for those providing creative, premedia and printing services, worldwide.
G7® specifies the components of an image that define a similar "visual appearance" to the human eye. To do this, the G7 Specification:
• defines a colormetric definition for gray balance |
G7 development was driven by print buyers and agencies. Buyers were pleased with print quality. , they were frustrated because . Yet while everything was printed to the "numbers" when compared side by side the visual appearance did not appear to match based on principles of digital imaging, spectrophotometry, and computer-to-plate (CtP) technologies. G7 is currently being applied to many types of printing including commercial and publication printing, newsprint and even flexo. This publication utilizes the existing ISO 12647 Standards as the basis for good printing. G7 specifies printing with inks defined by ISO 2846-1 so that the dry solids measure as close as possible to the ISO CIELab values for seven colors ─ the four primary colors and three 2-color overprints specified in ISO 12647. Because our goal is to simplify calibration help the printers reliably achieve a close “visual match” from proof to press, G7 breaks from tradition by focusing on colorimetric data for gray balance in the mid-tones rather than on densitometric aims, i.e. dot gain, for each color. G7 is named for its gray scale calibration technique and the 7 ISO ink colors it requires. G7 is a trademark of IDEAlliance.Although G7 was developed by the efforts of the GRACoL Committee, it should not be confused with GRACoL or with GRACoL 7.
NOTE: G7 is a registered trademark of IDEAlliance.
Frequently Asked Questions about G7
Who Developed G7?
The basics of G7 were developed by its inventor Don Hutcheson, Hutchcolor LLC. Hutcheson granted to IDEAlliance intellectual property rights, free-of-charge, including the right to publish IDEAlliance specifications based on this intellectual property, the right to develop and deliver training materials based on the IP, and the right to use the intellectual property as the basis for IDEAlliance programs. Hutcheson and a team from the IDEAlliance GRACoL Committee refined the process controls defining visual similarity and G7 was first published as an IDEAlliance Specification in 2007. Today, because of its broad application beyond sheetfed offset printing, G7 is advanced and maintained by the IDEAlliance Print Properties and Colorimetrics Working Group.
What does the G7 mean?
The name G7 was derived from “G” for gray balance and the 7 ISO colors, CMYK/RGB. G7 is not the same as GRACoL 7 which was the 7th Edition of the IDEAlliance GRACoL Specification.
Is G7 a printing standard? Or a proofing standard?
Actually G7 is neither a printing standard nor a proofing standard. In fact, it is not a standard at all. G7 defines process controls for the neutrality and tonality of an image whether on a proof or from a press of any kind
Is G7 the same as GRACoL? SWOP?
GRACoL provides specifications and guidelines for commercial sheetfed offset printing. SWOP provides specifications and guidelines for publication web offset and gravure printing. Both specifications address proofing as well. While G7 was developed under the jurisdiction of the IDEAlliance GRACoL Committee, its application today is far beyond the world of commercial sheetfed printing.
The G7 gray balance and Neutral Print Density Curves are being used to develop a family of characterization data sets (i.e. profiles) that for the first time have a shared visual appearance. The new IDEAlliance characterization data sets for GRACoL and SWOP were both developed based on G7. When compared visually, GRACoL and SWOP proofs and printed output have an amazing similarity. This is because the image neutrality and the tonality are identical for both GRACoL and SWOP. In years to come we expect to see the family of characterization datasets based on G7 to grow, enabling print buys across printing device types and substrates to have a shared visual appearance despite differences in substrate, gamut, and device-dependent printing characteristics.
Does G7 compete with ISO standards?
IDEAlliance has always intended that their G7 efforts be in compliance with ISO 12647. For the sheetfed offset world we recommend using inks compliant with ISO 2846. We believe G7 compliments and enhances existing ISO standards. In places where G7 provides innovations beyond ISO 12647, those innovations are submitted to ANSI/CGATS and from there to ISO for inclusion in the body of international standards. We have contributed to the new draft specification ISO TR 10126 which includes G7 process controls documented as the “Near Neutral” methodology.
Are there Different G7 Conformance Levels?
The Print Properties and Colorimetrics Committee has identified two conformance levels for G7:
G7-GT complies with the G7 gray balance and tonality specifications. It does not apply color management but focuses on achieving tight tolerances for gray balance and for the neutral print density curve.
G7 Targeted complies with the G7 gray balance and tonality specifications but in addition uses color management to achieve a color match to an aim characterization data set. So G7 GRACoL meets GRACoL aims in addition to matching the G7 gray balance and NPDCs. And G7 SWOP meets SWOP aims in addition to matching the gray balance and tone curves.