Webinar -- G7 for Grand Format Printers

How consistent is your color in printing?

G7 for Grand Format Printers

X-Rite Color Management forGrand Format Printers

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

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

First Webinar o PDF Slides – http://slidesha.re/17vHP5W

o Recorded Webinar – http://bit.ly/1coYVIi

• This is webinar is also being recordedo We will send links to the slides and recording

Part 1 — Printer Calibration

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

Agenda

(1st Poll Question)

• Have you implemented G7 calibration method at your business?

• If you have not implemented G7, why not?

(2nd Poll Question)

• 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 filesare either RGB or CMYK

Can you see a difference?

GRACoL– ICC profile Assigned

US Web Coated (SWOP) v2 – Original

GRACoL– ICC profile Assigned

US Web Coated (SWOP) v2 – Original

Can you see a difference?

• Equal values of RGB = neutrality

• Common agreed gray balance triplet for CMYK for mid-tone is 50/40/40/0o GRACoL 2006 and Web Coated SWOP 2006 are based on G7

calibration process.

Neutrals in RGB and CMYK

AFTER G7 Correction

Before G7 Correction

• 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?

• 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

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

• ICC profiles are not designed to fix or compensate o poor color calibration

o poor gray balance

o Consistent visual appearance

ICC Profiles

• 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 accuracyo 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

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

• 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 charto 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

How many near neutral and neutral patches do you see?

Black Generation options define how to gray is built but.....o Black Gen setting can minimize color bias but do not address tone

response curveo Tone Response curve provides the “look” of output

Poor Gray Balance — Color Cast

• Most Grand Format Printing RIPs do not offer iterative color tuningo Too many medias, not enough time o Not practical – there is typically some variance in

printing that is higher than color tolerance targetedo 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

•Output color gamut is frequently smaller than the source color gamut of SWOP or GRACoLo Using standard ICC profiles sometimes can result in

severe compressiono 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’tGRACoL or SWOP

G7 Grayscaleo Basic requirement for G7 Qualification

G7 Targetedo Used for printing presses – not Grand Formato Color Gamut similar to ISO 12647-2 / GRACoL / TR-

15

G7 ColorSpaceo 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

G7 Extremeo No color management (no reference print

conditions) but G7 Grayscale appliedo 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

Orig

inal

GR

AC

oL S

ep

GR

AC

oL S

ep p

rinte

d w

/o C

olo

r M

ana

gem

ent

File Printed with G7 cal but no Color Management

GR

AC

oL S

ep p

rinte

d w

/o C

olo

r M

ana

gem

ent

File Printed with G7 cal but no Color Management

AKA, G7 Extreme

Original GRACoL Sep

Original GRACoL Sep

• 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 patcheso Improves the shelf life of ICC profile

if based upon G7

Benefits of G7 for Your Business

• 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

Visual Contrast — Target L*95 Paper

Visual ContrastPaper (LAB) 95, -0.78, -1.75

• P2P25x has 300 patches

• Chart is formatted to be compatible with lots of measurement devices

Standard G7 Test Form

• Chromix Curve3

• Tucanna PrintControlPro

• Alwan PrintStandardizerX

Tools for Generating G7Correction Curves

• Chromix Verify

• Tucanna RapidCheck

• Alwan Verify

• SpotOn! Verify

• EFI ColorVerifier

• GMG ProofControl

• Bodoni ProofSign

Tools for Checking G7 Conformance

AFTER G7 Correction

Before G7 Correction

Before G7 Calibration

After G7 Calibration

Gray Balance Compensation

• 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 Densitieso 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

• Use ICC profile charts to smooth datao Apply smoothed data to P2P25x

G7 for the Advanced

• Do not resize the P2P25x imageo Special designed in a dithered pattern for accuracy

• Print at least two P2P25x on each test formo Rotate one of the charts 180°o Average data!! Either externally or in the G7 toolo You should have at least two data files to average, more the

better!

• Consider a program to collect measurements over timeo Improves correction curves by statistically more datao Proactive instead of Reactive (uh, what happened?)

Tips for Success

(Poll Question)

• What is the most troublesome way customers communicate color?

Device Link ICC Profiles

Best way to handle color conversiono No trip through LAB o “Baked” color conversiono Fastest since all calculations are done, not only the fly as in a

traditional in RIP color conversiono Best method for scaling source to destination

Several Device Link generation products are availableo They offer features on how to handle scalingo Purity of colorso Black generation preservation

X-Rite i1Profiler v1.5o 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

Last — Third Webinar

• Talk more about device link color matching

• Delve deep in how to communicate color intentions throughout productiono How to handle customer supplied --

• Proofs from a third-party vendor

• Print samples

• Named colors – PMS

• Brand color matching

• Communicating Color for Grand Formato Input | Reference color spaces

o RGB files

o New and old school PMS color

Upcoming Webinars

September25

2013

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How consistent is your color in printing?

G7 for Grand Format Printers

X-Rite Color Management forGrand Format Printers