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Webinar -- G7 for Grand Format Printers
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
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
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
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
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
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
