This document discusses using G7 calibration for grand format printers to achieve consistent color in printing. It provides an overview of G7 calibration including: - G7 calibration can provide benefits for non-lithographic printing processes by improving neutrality and visual contrast. - There are different levels of G7 compliance including G7 grayscale, G7 targeted, and G7 colorspace which can be used with or without color management. - Tools exist to generate and verify G7 correction curves to calibrate printers to the G7 standard and improve color consistency.

1. How consistent
is your color in printing?
G7 for Grand Format Printers
X-Rite Color Management for
Grand Format Printers

2. Sponsor
• X-Rite is the global leader in color
science and technology
• Pantone is part of the family
• Mature product line for printing and
graphic arts markets

3. Today's Speaker – Dan Reid
o Founded in 1998 to help business
realize the benefits of color management
o Consulting and product sales for some of
the largest and smallest print providers
o Early adopter of G7 calibration technique
for non-litho applications. Certified by IDEAlliance in 2006

4. First Webinar
o PDF Slides – http://slidesha.re/17vHP5W
o Recorded Webinar – http://bit.ly/1coYVIi
• This is webinar is also being recorded
o We will send links to the slides and recording
Part 1 — Printer Calibration

5. • Quick Poll
• G7 Myths & Background
• Ways to Achieve G7 Compliance
• G7 Tools to Achieve Compliance
• Tips
• QA
Agenda

6. (1st Poll Question)
• Have you implemented G7 calibration
method at your business?

7. • If you have not
implemented G7, why not?
(2nd Poll Question)

8. • RGB files by their nature are neutral
• Files from RGB to CMYK are typically a US
Web Coated (SWOP) v2 or GRACoL (2006)
separations
• Though US Web Coated in not based on G7
using GRACoL as a source ICC profile in your
RIP usually works
Invariably source files
are either RGB or CMYK

9. Can you see a difference?
GRACoL
– ICC profile Assigned
US Web Coated (SWOP) v2
– Original

10. GRACoL
– ICC profile Assigned
US Web Coated (SWOP) v2
– Original
Can you see a difference?

11. • Equal values of RGB = neutrality
• Common agreed gray balance triplet for CMYK
for mid-tone is 50/40/40/0
o GRACoL 2006 and Web Coated SWOP 2006 are based on G7
calibration process.
Neutrals in RGB and CMYK

12. AFTER G7 Correction
Before G7 Correction

13. • Just getting prints neutral won't alone achieve
a visual match
• Using a method to consistently achieve a
visual contrast relative to the substrate color
is missing key
So neutrality is well defined,
what about visual contrast?

14. • Formally introduced in 2006 by IDEAlliance
• Origins and original calculations were based
on lithographic printing
• Slowly introduced and tested in other printing
processes
• Most Grand Format RIPs supports G7
calibration method either directly or
indirectly by color reference
Brief History of G7 Method

15. Common Myths about G7
• G7 does not replace color management
• If you are using a printing process other
than commercial (litho) printing then G7
calibration provides little benefit
• Color ICC profiles can achieve the same
results

16. •ICC profiles are not
designed to fix or
compensate
o poor color calibration
o poor gray balance
o Consistent visual
appearance
ICC Profiles

17. • Targeting G7 via color management may not be
sufficient meet required tolerance metrics
• Output (Printer) ICC profile typically does not have enough
samples to be accurate enough
• Output (Printer) ICC profile does not have enough
resolution for accuracy
o Table resolution needs to be higher resulting in larger sized ICC
profiles (MB). Not a huge deal, but not all RIP profiling
solutions allow adjustable table resolution
• May necessitate manual ICC Profile tuning to achieve
a match within tolerance
• Possible but requires some trial and error
• Tedious | time consuming
G7 via Color Reference

18. Of course no one would consider building ICC
profiles without first optimizing color balance
There could be a color bias the ICC profile will
faithfully record
ICC profile will not automatically re-distribute
color tones to achieve smooth gradients
Poor Color Calibration

19. • If your ICC profiling chart prints with a color cast
then the ICC profiling software will record that
bias
• ICC Profiling Black Generation options define
how to black is used to create neutrals
(GCR/UCR)
o Invariably there are not enough samples available to provide
sufficient accuracy on first attempt from the ICC profiling chart
o Improvements are possible by iterating correction by re-printing
profiling charts with corrections applied, measure, and evaluating if
further improvement is needed
Poor Gray Balance — Color Cast

20. How many near neutral and
neutral patches do you see?

21. Black Generation options define how to
gray is built but.....
o Black Gen setting can minimize color bias but do not address tone
response curve
o Tone Response curve provides the “look” of output
Poor Gray Balance — Color Cast

22. • Most Grand Format Printing RIPs do not offer
iterative color tuning
o Too many medias, not enough time
o Not practical – there is typically some variance in
printing that is higher than color tolerance targeted
o Traditional color match using ICC profiles in a RIP
may be sufficient to pass within tolerance
• No mechanism to compensate other than re-linearization which
may not be sufficient since the goal is not meeting a gray
balance tolerance
• May require more frequent profiling of printing device if re-
linearization does bring the printer back in line within tolerance
G7 via Color Reference

23. •Output color gamut is frequently smaller than
the source color gamut of SWOP or GRACoL
o Using standard ICC profiles sometimes can result in
severe compression
o Accuracy in color compression is not always
sufficient
• Directly related to how many samples are taken
• Some color / neutrals need additional sampling to improve
accuracy
Grand Format Printing ain’t
GRACoL or SWOP

24. G7 Grayscale
o Basic requirement for G7 Qualification
G7 Targeted
o Used for printing presses – not Grand Format
o Color Gamut similar to ISO 12647-2 / GRACoL / TR-
15
G7 ColorSpace
o G7 Grayscale required but many proofing RIPs use
color management instead to G7 correction curves
achieve G7 compliance
o Color Match verified against G7 reference typically
GRACoL or SWOP3
G7 Compliance Levels

25. G7 Extreme
o No color management (no reference print
conditions) but G7 Grayscale applied
o Defines setup where color gamut is larger that
source (ie GRACoL) and not compressed to meet a
reference like G7 ColorSpace
o Usually not “accurate” color but pleasing
G7 Compliance Levels

26. OriginalGRACoLSep
GRACoLSepprintedw/oColorManagement
File Printed with G7 cal but no
Color Management

27. GRACoLSepprintedw/oColorManagement
File Printed with G7 cal but no
Color Management
AKA, G7 Extreme

28. Original GRACoL Sep
Original GRACoL Sep

29. • Better and more consistent match across
printing technologies
• Improved visual color appearance across
different substrates
• Alignment with source ICC profiles based upon
G7 method (GRACoL & SWOP)
• Improved recalibration process that aligns with
a visual system using only 300 patches
o Improves the shelf life of ICC profile
if based upon G7
Benefits of G7 for Your Business

30. • This defines how contrasty a image appears to
the eye.
o Some materials inherently have a lower visual
contrast
o Especially problematic in non-litho applications
o Media and printing technology have direct impact on
how an image contrast appears to the eye
Visual Contrast

31. Visual Contrast
— Target L*95 Paper

32. Visual Contrast
Paper (LAB) 95, -0.78, -1.75

33. • P2P25x has 300 patches
• Chart is formatted to be compatible with lots of
measurement devices
Standard G7 Test Form

34. • Chromix Curve3
• Tucanna PrintControlPro
• Alwan PrintStandardizerX
Tools for Generating G7
Correction Curves

35. • Chromix Verify
• Tucanna RapidCheck
• Alwan Verify
• SpotOn! Verify
• EFI ColorVerifier
• GMG ProofControl
• Bodoni ProofSign
Tools for Checking G7
Conformance

36. AFTER G7 Correction
Before G7 Correction

37. Before G7 Calibration

38. After G7 Calibration

39. Gray Balance Compensation

40. • Relative (native) Black Aim Point instead of
targeting absolute reference of (0a*0b*)
o Legacy G7 method black aim point is for absolute black
reference
o Though curves may be smoother you may fail G7
qualification by not being able to hold gray balance in
SC
• Normalize High Densities
o Designed to smooth out drastic curve corrections in the
shadows
o Again this may make it difficult to pass G7 Qual in
shadow areas
G7 for the Advanced

41. • Use ICC profile charts to smooth data
o Apply smoothed data to P2P25x
G7 for the Advanced

42. • Do not resize the P2P25x image
o Special designed in a dithered pattern for accuracy
• Print at least two P2P25x on each test form
o Rotate one of the charts 180°
o Average data!! Either externally or in the G7 tool
o You should have at least two data files to average, more the
better!
• Consider a program to collect measurements
over time
o Improves correction curves by statistically more data
o Proactive instead of Reactive (uh, what happened?)
Tips for Success

43. (Poll Question)
• What is the most troublesome way
customers communicate color?

44. Device Link ICC Profiles
Best way to handle color conversion
o No trip through LAB
o “Baked” color conversion
o Fastest since all calculations are done, not only the fly as in a
traditional in RIP color conversion
o Best method for scaling source to destination
Several Device Link generation products are
available
o They offer features on how to handle scaling
o Purity of colors
o Black generation preservation

45. X-Rite i1Profiler v1.5
o Adds Device Link Functionality
• Improvement in color gradients not banding as in a traditional LAB conversion
• Maintains purity of source black generation to be mapped to the destination
instead of converting to 4/C black in LAB conversion
Device Link ICC Profiles

46. Last — Third Webinar
• Talk more about device link color matching
• Delve deep in how to communicate color
intentions throughout production
o How to handle customer supplied --
• Proofs from a third-party vendor
• Print samples
• Named colors – PMS
• Brand color matching

47. • Communicating Color for Grand Format
o Input | Reference color spaces
o RGB files
o New and old school PMS color
Upcoming Webinars
September
25
2013

48. Questions and Answers
Discuss this topic further:
#G7grandformat
Type your questions into the side bar on right.

49. How consistent
is your color in printing?
G7 for Grand Format Printers
X-Rite Color Management for
Grand Format Printers