G7

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==More Information==
==More Information==
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* This is an article by Steve Upton which originally appeared in CHROMiX ColorNews.  He discusses some of the history of why we have come to the point of using gray balance to calibrate presses, the differences between GRACoL 7 and G7, and how CHROMiX has become involved.
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* Article: <b>The Ins and Outs of GRACoL 7 and G7</b> This is an article by Steve Upton which originally appeared in CHROMiX ColorNews.  He discusses some of the history of why we have come to the point of using gray balance to calibrate presses, the differences between GRACoL 7 and G7, and how CHROMiX has become involved.
http://www.colorwiki.com/wiki/The_Ins_and_Outs_of_GRACoL_7_and_G7
http://www.colorwiki.com/wiki/The_Ins_and_Outs_of_GRACoL_7_and_G7

Revision as of 22:46, 13 May 2009

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/industry_resources/branding_media_and_color/g7/how_to

An updated amendment for the "How to" is here:

Amendments to G7 How to

A list of downloadable G7 documents is here: http://www.idealliance.org/industry_resources/branding_media_and_color/gracol

IDEAlink Curve

IDEAlink Curve software

IDEAlink Curve is software that greatly simplifies the process of G7 calibration. Doing it "by hand" involves manually drawing out curves on graph paper. This software makes the process automatic, consistent, allows for automatic averaging of multiple press sheets, compares the press run to SWOP and GRACoL standards, automatically creates correction values for the most popular RIPs, provides several visual graphs for feedback on your press condition, and more.

http://www.idealliance.org/industry_resources/branding_media_and_color/gracol/idealink_curve_software

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

https://www2.chromix.com/idealink

More Information

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

http://www.paperspecspro.com/blog/?p=359

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