G7

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G7® is a Specification defined by the Print Properties and Colorimetrics Working Group of IDEAlliance.

G7 is a method for matching color across multiple printing devices, such as printing presses and proofing systems. It can be applied to any printer that has a calibration process (usually involving adjusting color "curves" in a RIP) that allows control over CMYK inks. These would include web presses, sheet-fed presses, proofing systems, inkjet printers being driven by RIPs. The goal of G7 is to provide visually consistent, repeatable color between different devices (like proofers and printers) as well as different presses, and even different facilities. The emphasis in this specification is on gray balance. Since human vision sees differences in gray more readily than more saturated colors, this specification is more likely to result in successful visual "matching" than merely matching solid ink densities which is typically done for more traditional processes.

Note that G7 is a specification - not a standard. It can be used in addition to other industry printing specifications such as SWOP, or GRACoL.

Contents

From the IDEAlliance website

G7® specifies the components of an image that define a similar "visual appearance" to the human eye. To do this, the G7 Specification:

History

Initially G7 was developed by the IDEAlliance GRACoL Working Group. But as adoption of G7 grew, it became clear that the application of this specification that enables printers to reproduce a similar visual appearance across printing types and substrates should be addressed by a group with reach beyond the focus on sheetfed offset printing that is unique to the GRACoL working group. Today, through the PPC Working Group, experts from across the spectrum of printing disciplines contribute to this important IDEAlliance Specification.

How to get it

The G7 specification is managed by IDEAlliance. Documentation describing the process is freely available at the IDEAlliance website which describes the specification and how to achieve it.

"How to" documents are available here:

http://www.idealliance.org/downloads/g7-g7-process-control-pass-fail-guidelines


A list of downloadable G7 documents is here: http://www.idealliance.org/specifications/gracol/resources/9

IDEAlink Curve

IDEAlink Curve software

IDEAlink Curve was the first software that greatly simplified the process of G7 calibration. Doing it "by hand" involved manually drawing out curves on graph paper. This software made the process automatic, consistent, allowed for automatic averaging of multiple press sheets, compared the press run to SWOP and GRACoL standards, automatically created correction values for the most popular RIPs, provided several visual graphs for feedback on your press condition, and more.

As of 2010, IDEALink Curve is no longer available for purchase new. It was replaced by Curve2, which was in turn replaced by Curve3. https://www2.chromix.com/idealink


Curve2

Curve2 software logo

In 2009 CHROMiX and Hutchcolor released Curve2. This was an upgrade to the original IDEAlink Curve software. Curve2 is not an IDEAlliance product as was the original Curve software.

Links to download the software (requires username and password to run), links to beta software, and the registration page are at the CHROMiX website:

https://www.chromix.com/curve2

Curve3

Curve3

In April of 2013, CHROMiX and Hutchcolor released a new version called Curve3.

Curve3 allows calibration of special (non-process) inks, TVI calibration, introduces a high quality smoothing function, and more options for inkjet calibration.

https://www2.chromix.com/curve3

More Information

GRACoL

http://www.colorwiki.com/wiki/The_Ins_and_Outs_of_GRACoL_7_and_G7

ColorNews issue #23 - Gracol 7 and G7

http://g7.supremegraphics.com/

http://ideallianceg7.blogspot.com/

G7™ Training

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