G7 and ISO 12647 are the two references most offset printers run into. They are not rivals so much as two routes to the same destination: predictable, repeatable color. Here is how they differ and how to choose, or combine, them.
Two routes to the same goal
Both methods aim to make color consistent and reproducible. The difference is what they put first: ISO 12647 fixes target values, while G7 fixes how gray and tonality should appear, then lets you reach the rest from there.
What ISO 12647 controls
ISO 12647-2 defines aim values for the primaries, tone value increase and tolerances on a given substrate class. It is a specification: print these numbers, within this spread, and you conform.
What G7 controls
G7 is a calibration method built around gray balance and a neutral print density curve (NPDC). By matching a shared gray appearance relative to the substrate, jobs look consistent across devices and plants, even on different papers.
How to choose, or combine
- Working mostly in the North American supply chain or matching by gray appearance: G7 fits naturally.
- Driven by European or ISO-based specifications and aim values: ISO 12647-2 is the reference.
- In practice many printers calibrate with G7, then verify against ISO 12647 aim values, combining both.