G7 Press Control System Certification
G7 Press Control System Certification Home | Pricing & Application | Certified Systems | Program Overview
Introduced as of January, 2016, the Idealliance G7 Press Control System Certification program validates a press control system’s ability to monitor and control G7 gray balance and tonality, supporting print service providers' ability to realize the full benefits of the G7 methodology.
Since its introduction in 2005, the G7 calibration method has been adopted by countless printing facilities world-wide. What makes it popular is that all properly G7-calibrated printing systems deliver the same predictable, standardized gray balance and tonality, which is a key requirement for accurate and predictable color printing.
A certified G7 Press Control System automates the process of measuring special G7 gray control patches. Any deviation in those patches are then used to guide the system back to its ideal “G7 appearance.” Utilizing G7 metrics that have been added to a press control system allows the press operator to see in real time how close to the G7 targets the printing is, and what adjustments are needed to achieve G7 compliance.
A Certified G7 Press Control System…
- Can be submitted for certification by a manufacturer or vendor of an automated press control system
- Is capable of measuring G7 gray control patches in real-time
- Offers real-time monitoring and/or adjustment of ink quantities to maintain consistent appearance of the printedresult
- Is accompanied by an Application Data Sheet (ADS) describing the actual steps an end-user must take to successfully repeat the certificationprocess.
What the Program Certifies
The testing program is based on a series of sample data representing different printing conditions. The program certifies the candidate system’s ability to:
- Calculate the ideal G7 target values for tonality and gray balance
- Suggest ink quantity adjustment trends likely to help the press meet those G7 targetvalues
- Correctly apply the math in TR015 to calculate target values for HR_cmy, HC_cmy, SC_cmy HR_k, HC_k and SC_k for the test conditions
- Indicate to the press operator, and/or directly send to the press, approximate ink adjustment values necessary to achieve the desired target values.
What the Program Does Not Certify
- G7 press calibration (e.g. calculating offset platecurves).
- Control of single-ink TVI or “Dot Gain” values from other specifications or standards, such as ISO12647-2.
- Control of solid ink colorimetric or density values according to any specification such as GRACoL, or the ISO 12647-2standard.
- Accuracy of production prints compared to a colorimetric reference print condition (CRPC) such asGRACoL, or a physical proof or referenceprint.
Limitations and Assumptions
The certification process only evaluates the system’s ability to control the G7 parameters of gray balance and gray tonality, and pays no attention to how the suggested G7 adjustments might affect solid ink values orTVI.
Idealliance recognizes that in many cases, press control based only on G7 parameters may not be sufficient, however for testing purposes, it is essential to measure G7 press control separately from other press controlvariables.
For practical reasons, the certification process is limited to testing the system’s response to synthetic (recorded) colorimetric data with no actual press runsinvolved.
Presumably a G7 press control system can only steer a press to meet G7 compliance if the press has already been G7-calibrated, or is naturally able to meet G7 parameters.