G7 Methodology

About G7®

G7, a calibration methodology developed by IDEAlliance, enables different proofing devices, screen presses and digital printers to produce a very similar appearance regardless of substrate, line count, ink type or printing condition. IDEAlliance (International Digital Enterprise Alliance) is promoting the G7 method as a constant component of all future print specifications, and has offered it openly for adoption by all standards associations, for all types of imaging or media, worldwide.

G7 is a method for a media-independent, universal grayscale appearance that is applicable to all color imaging processes. G7 manages gray balance and tonality using simple CMYK calibration curves and provides a basis for “shared appearance” that aligns multiple printing platforms as closely as possible to each other without additional color management. With G7, you can achieve a common visual appearance in your prints — even if you are using different materials.

How it Works

G7 adjusts the device via typical CMYK RIP curves, or other device calibration utilities, to match a pre-defined NPDC (Neutral Print Density Curve) and gray balance. Calibrating a device to G7 valves will give it the same neutral gray scale appearance as all other G7 devices. This is the secret of the G7 method — achieving a common visual appearance, regardless of what colorants you use or how they are applied to the substrate. What’s more — there’s no need for additional color management.

What it’s Not

Now that you know what G7 is, take a look at what it isn’t.

• G7 is not an ICC color management system, nor does it replace it.
• G7 is not an ISO standard, but rather a specification to help printers meet those standards.

G7 vs. GRACol 7

G7 is not the same as the GRACoL 7 print specification. G7 is a calibration method; the 'G' refers to calibrating Gray values, while the '7' refers to the seven primary color values defined in the ISO 12647-2 printing standard: Cyan, Magenta, Yellow, Black (K), Red (M+Y), Green (C+Y) and Blue (C+M). Although originally intended for commercial offset printing, the G7 method is applicable to virtually any CMYK imaging process and has been successfully tested on a wide range of processes, including screen, offset, newsprint, gravure, flexography, dye-sublimation, ink-jet and electrophotography, as well as a wide range of AM and FM screening methods.

G7 allows for a non-subjective specification of standardized process color output. Standardizing to a common neutral gray produces a file with no cast. This means the print truly represents the file because no color cast is added to it. This allows printers to have confidence that the print is correct, repeatable and non-subjective, saving them both the cost and time of reprinting.