Calibrating, Printing and Proofing by the G7™ Method

Calibrating, Printing and Proofing by the G7 Method Version 6, August 2006
8.5 Correcting Gray Balance in IDEAlink Curve
8.5.1 Switching gray balance on and off in IDEAlink Curve
Gray balance correction can be switched ON (default condition) by checking the Gray Balance button in
the Create Curves window. When the Gray Balance button is checked, IDEAlink Curve calculates
separate gray balance correction curves for C, M and Y.
Gray balance correction can be switched OFF by un-checking the Gray Balance button in the Create
Curves window. When the Gray Balance button is un-checked, IDEAlink Curve calculates identical
CMY curve values based only on the NPDC curve aims.
8.5.2 Changing the gray balance basis color
Gray Balance can be based on the color of the actual paper the P2P target was printed on by clicking
Gray Options.. and checking the Paper White button. Alternately, gray balance can be based on an
arbitrary paper color (for example the paper color of the characterization data you are trying to imitate)
by clicking Custom White and entering the a* and b* values manually.
8.5.3 Smoothed gray balance
By default IDEAlink Curve produces 'smoothed' gray balance curves based on an averaged analysis of
the whole CMY gray scale. This minimizes the possibility of unwanted side-effects on devices whose
gray balance is unstable - particularly offset presses. By un-checking the Smoothed Gray Balance
button you will create more complex CMY correction curves based on the separate errors discovered at
12.5%, 25%, 37.5%, 50%, 62.5% and 75% cyan values.
CAUTION: Switching off Smoothed Gray Balance is only recommended if the device has a highly
stable and repeatable gray balance error. It is usually safe to switch smoothed gray balance OFF for
ink jet printers and laminate-based pre-press proofing systems. It is usually best to leave Smoothed
Gray Balance ON for offset presses.
8.6 Apply new aim values to RIP or CtP device
Apply the new gray-balanced aim values from your worksheet to the RIP or calibration utility. Note that
some RIPs require you to enter 'Measured' values instead of 'Wanted' values, while other RIPs ask for
delta values. This method assumes you know how to modify the New Aim values accordingly. When in
doubt, remember the new aim value is what each curve point should be AFTER correction.
8.7 When NOT to apply gray balance in RIP curves
Gray balance should NOT be corrected in RIP curves if;
• The device is already nearly neutral.
• You feel it can be neutralized next time you print by simple adjustments, for example by modifying
CMY ink quantities (usually true in offset printing).
29 Copyright © International Digital Enterprise Alliance, Inc. [IDEAlliance] (2006). All Rights Reserved.