Calibrating, Printing and Proofing by the G7™ Method
Calibrating, Printing and Proofing by the G7™ Method
Calibrating, Printing and Proofing by the G7™ Method
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Calibrating</strong>, <strong>Printing</strong> <strong>and</strong> <strong>Proofing</strong> <strong>by</strong> <strong>the</strong> G7 <strong>Method</strong> Version 6, August 2006<br />
two or more calibration utilities, one for basic 'linearization' <strong>and</strong> ano<strong>the</strong>r for user-editable curve<br />
adjustment, OR if this is an ink-jet device <strong>and</strong> <strong>the</strong> manufacturer's calibration produces ink-limiting<br />
tables.<br />
• If multi-stage calibration utilities exist, perform <strong>the</strong> manufacturer's recommended linearization<br />
method as a base-line calibration, <strong>and</strong> use <strong>the</strong> user-editable curve adjustment to implement G7<br />
NPDC <strong>and</strong> gray balance calibration.<br />
• If <strong>the</strong> manufacturer's instructions involve any kind of ICC-based or custom color management,<br />
disable this function during G7 calibration.<br />
IMPORTANT: Make sure any ICC or o<strong>the</strong>r color management functions are turned OFF prior to G7<br />
calibration. (These should be re-enabled after <strong>the</strong> calibration <strong>and</strong> profiling process is completed.)<br />
10.5 Print <strong>the</strong> proofing form target<br />
Print ei<strong>the</strong>r <strong>the</strong> GRACoL 7 Press Form (www.printtools.org) or your own version of it (see 5.2 Assemble<br />
<strong>the</strong> press form)<br />
10.6 Measure <strong>the</strong> Press2Proof (P2P) target<br />
Measure <strong>the</strong> K-only gray scale (column 4) <strong>and</strong> CMY-only (column 5) of <strong>the</strong> P2P target.<br />
(see 7.2)<br />
10.7 Plot <strong>the</strong> curves<br />
(see 7.3)<br />
10.8 Align end-points at 100%<br />
(see 7.4)<br />
10.9 Choose <strong>the</strong> optimum curve points<br />
(see 7.5)<br />
10.10 Calculate <strong>the</strong> RIP curve correction values<br />
(see 7.6)<br />
10.11 Evaluate <strong>and</strong> adjust gray balance<br />
(See section 8)<br />
Unlike presses, most proofers do NOT allow gray balance adjustment <strong>by</strong> physical changes. Proofer gray<br />
balance is typically achieved EITHER with three separate RIP curves for C, M <strong>and</strong> Y, OR with a 4-D<br />
transform (using ICC profiles or some o<strong>the</strong>r color management system).<br />
If <strong>the</strong> proofer already requires ICC profiles (or equivalent) for color matching, <strong>the</strong>re may be less<br />
advantage in calibrating <strong>the</strong> proofer to G7 gray balance <strong>and</strong> NPDC curves, but if <strong>the</strong> proofer is capable<br />
of approximating a commercial press WITHOUT a 4-D transform (true of most halftone digital proofers)<br />
<strong>the</strong>n calibrating to G7 gray balance <strong>and</strong> NPDC curves should optimize quality, even without fur<strong>the</strong>r color<br />
management.<br />
10.11.1 Gray balance precision<br />
When calculating gray balance corrections for a proofer (or any o<strong>the</strong>r stable device) <strong>by</strong> <strong>the</strong> graph paper<br />
method, every block in <strong>the</strong> GrayFinder target should be used. When using IDEAlink Curve, switch OFF<br />
‘Smoo<strong>the</strong>d Gray Balance’ under ‘Gray Options..’<br />
10.12 Apply new aim values to RIP<br />
(Section 8)<br />
33 Copyright © International Digital Enterprise Alliance, Inc. [IDEAlliance] (2006). All Rights Reserved.