Living in a World Without Color(bars)johnthemathguy.com/files/pdf/Living in a World Without...

The Art and Science of Color Management

Living in a World

Without Color(bars)

John Seymour

Principal Research Engineer

QuadTech


Living in a World

Without Color(bars)

John Seymour

Applied Mathematician

QuadTech


I don't want to live in a world

without love or grief or beauty

or color bars, I'd rather die.

Dana Winter,

Invasion of the Body Snatchers


Why no colorbars?

1. Colorbars aren’t welcome


Why no colorbars?

Color patches can hide in a flap


Why no colorbars?

What if there is no flap?


Why no colorbars?

No color patches

Hershey’s has a

2.0 DECMC tolerance


Why no colorbars?

No color patches


Why no colorbars?

Color patches


Why no colorbars?

Magazines are trimmed

Colorbars can hide in the trim


Why no colorbars?

Newspapers are not trimmed

Colorbars can run,

but they can’t hide


Why no colorbars?

Where is the eye drawn?


Market research

2009 – QuadTech sales force collected newspapers

142 newspapers, twelve countries


Market research Belgium Metro

Montreal La Presse

Montreal Le Journal

Montreal Les Affaires

China Guangzhou Daily

Santo Domingo Listin Diario

Manchester Daily Express

London Daily Express

Manchester Daily Mail

Manchester Daily Telegraph

London Daily Telegraph

London Evening Standard

London Guardian

London Observer

Manchester Times

London Times

Finland Lansi-Savo

France La Depeche du Midi

Nimes Le Fiagro (Nimes)

Paris Le Fiagro (Paris)

France Le Progress

Germany Darmstädter Echo

Jalandhar Ajit Samachar

Kolkatta Anand Bazar Patrika

India Business Line

Agra Dainik Jagran

Noida Dainik Jagran

Ludhiana Dainik Jagran

Varanasi Dainik Jagran

Jalandhar Dainik Jagran

Delhi Dainik Jagran

Ludhiana Dainik Jagran

Meerut Dainik Jagran

Hyderabad Deccan Chronicle

Chennai Deccan Chronicle

Bangalore Deccan Herald

Mangalore Deccan Herald

Dharwad Deccan Herald

Pondicherry Dinakaran

Salem Dinakaran

Coimbatore Dinakaran

Madurai Dinakaran

Trichy Dinakaran

Vellore Dinakaran

Tirunelveli Dinakaran

Chennai Dinakaran

Madurai Dinamalar

Chennai Dinamalar

Coimbatore Dinamalar

Ahmedabad Divya Bhaskar

Mumbai DNA

India DNA Money

Mumbai Economic Times

Delhi Economic Times

Pune Economic Times

Kolkata Economic Times

Lucknow Economic Times

Hyderabad Economic Times

Chennai Eenadu

Delhi Hindustan Times

Mumbai Hindustan Times

Noida Hindustan Times

Chennai Indian Express

Noida Indian Express

Pune Indian Express

Navi Mumbai Indian Express

Nagpur Lokmat

Pune Lokmat

Kolhapur Lokmat

Mumbai Lokmat

Mumbai Loksatta

Cochin Malayala Manorama

Trivandrum Malayala Manorama

Kozhikode Mathrubhumi

Kochi Mathrubhumi

Pallakkad Mathrubhumi

Calicut Mathrubhumi

Navi Mumbai Midday

Mumbai Midday

Mumbai Mumbai Mirror

Mumbai Navbharat Times

Delhi Punjab Kesari

Jalandhar Punjab Kesari

Ludhiana Punjab Kesari

Mumbai Ratnagiri Times

Pune Sakaal

Ahmedabad Sandesh

Mumbai Sandhyanand

Kolkatta Telegraph

Coimbatore The Hindu

Madurai The Hindu

Cochin The Hindu

Trichi The Hindu

Vijayawada The Hindu

Delhi The Hindu

Chandigarh The Tribune

Jalandhar The Tribune

New Delhi The Tribune

Mumbai Times of India

Delhi Times of India

Pune Times of India

Kolkata Times of India

Lucknow Times of India

Bangalore Times of India

Hyderabad Times of India

Chennai Vaartha

Korea Chosun Ilbo

Korea Donga report

Korea Korean Economic

Korea Mailgungie

Korea Segai Ilbo

Korea Ecoprint

Korea World Journal

Wisc. Rapids Daily Tribune

USA Dow Jones

Jacksonville Florida Times Union

Miami Miami Herald

New York NY Daily Times

Sarasota Sarasota Herald Trib

4 German nationals

Clave

Germany De Morgen

De Standard

De Tijd

Diario Libre

Financial Times

guardian

Herald Tribune

Het Laaste Nieuws

Hoy

Independent

France La Province

France Le Figaro

France Le Monde

France Le Soir

England Telegraph

USA The Times

LA Times

Chicage Tribune

Cleveland Plain Dealer

New York Times

Pittsburgh Catholic

Pittsburgh Courier

Pittsburgh Post Gazette

Pittsburgh Tribune Review

San Francisco Chronicle

Washington Post

USA Chronicle of Higher Ed

USA Jewish chronicle

New York Village Voice

Washington Sports Weekly

Washington USA Today

USA Barron's Weekly

USA Wall St. Journal

New York Times


Market research

How many had color patches?

None CMY Gray

Just Solids

Just Halftones Full

57 61 42 1 9

40% 43% 30% 1% 6%

Q: Why do they add up to more than 100%?

A: Overlap – e.g. use of gray and solids


Market research

What color patches did they have?

None CMY Gray

Just Solids

Just Halftones Full

57 61 42 1 9

40% 43% 30% 1% 6%

Ok with using full color bar

94% are not ok


Market research

What color patches did they have?

None CMY Gray

Just Solids

Just Halftones Full

57 61 42 1 9

40% 43% 30% 1% 6%

Not interested in quality??

60% are interested in quality

… but only 6% use the full colorbar


Treasure of the Sierra Madre

Color bars? We ain't got no color

bars! We don't need no color bars! I

don't have to show you any stinking

color bars!


Image-based color control

Currently at least five vendors

QuadTech AccuCam

Mitsubishi Diamond Eye

EAE Loop

QI IDS

Grafikontrol Colorscan

TKS - rumored

Several million dollars development X 6 companies = >$10M



Currently at least ten newspaper printers

Newsprinters (Knowsley and Broxbourne)

Sankei

Yomiuri

Nikkei

Chunichi

Nikkan Sports Printing

Polaris (Alesund)

Freie (Chemnitz)

Transcontinental (San Francisco and

Montreal) Corelio (Brussels)

5+10

16+?

110

??

??

??

??

3?

3

??

Roughly 150 systems… maybe $15M?



$25 M spent to get

color quality

without color bars

Why?

Isn’t the newspaper market shrinking?

Newspaper printers that survive

must reduce labor costs

print semi-commercial work


Why measure in the work?


2. Circumferential variation



Are they all the same color?

Copied from presentation by Franz Sigg at TAGA 2007



Also stolen from presentation by Franz Sigg at TAGA 2007



Stolen from my own presentation at TAGA 2007

ISO Tolerances

Density equivalents

Cyan – 2.2 DE

Magenta – 2.3 DE

Yellow – 5.0 DE

Black – 2.0 DE

DE of circ variation

50% to 100% of tolerance window!


Colorbars don’t predict the work

Siljander, Roger, and Richard S. Fisch, “Accuracy and Precision in Color Characterization,” 2001 TAGA Proceedings Sigg, Franz, “Noisy Dot Gain”, 2007 TAGA Proceedings Breede, Manfred, “The Effect of Ink Film Thickness Variation on Color Control in the Circumferential Printing Cylinder Direction of Offset Presses”, 2007 TAGA Proceedings Motaal and Sikander, “Repeatability of Ink Transfer and Color Management Lithography”, 2009 TAGA Proceedings

Papers with similar results





3. Standard patches don’t predict much of CMYK


Some fun data

• 102 Newspaper printers applying for SNAP

certification

• IT8 target from each (928 patches)

“An Analysis of the Current Status of Process Control for Color

Reproduction in Newspapers”, Seymour, Stanton, 2011 TAGA


Correlation of measurements

Some printers

leaned heavy on cyan solid

C90 heavy

Also a bit heavy on C80 M10

Heavier on C60, M60, Y50, K20?

Not heavier on K40



-10

-8

-6

-4

-2

0

2

4

6

8

0 50 100 150 200 250 300 M100

M90

Comparison of variation between M100 and M90



R² = 0.8221

-8

-6

-4

-2

0

2

4

6

8

-10 -8 -6 -4 -2 0 2 4 6 8 10

r2 = 0.8221



Correlation of measurements r2 = 0.8221

r is the correlation coefficient

82% of the variation is “explained”

82% of the variation is shared

The M100 patch

is a good proxy

for the M90




The M100 patch

is a good proxy

for the M90

If I want to track 90% magenta,

I can watch the magenta solid


Using patches as a proxy

Good proxy – sharing at least 50% of the variation

Fair proxy – sharing at least 25% of the variation



Solid M - good proxy for 10 of 928 patches

Solid Good proxy Fair proxy

Cyan 6 26

Magenta 10 61

Yellow 9 35

Black 3 9

C+M+Y+K 28 131

Four solids predict

3% of CMYK values



Mama always said life was like a

box of solid patches. You never

know what you're gonna get.

Forrest Gump



Patch set Num

patches

Good proxy Fair proxy

Four Solids 4 28 (3%) 131 (14%)

4 Solids + 40% 8 186 (20%) 587 (63%)

ISO 12647-2 requirements

only speak for

20% of the colors





3. Standard patches don’t predict much of CMYK

4. Tony the Tiger, flesh tones, mastheads


Who uses colorbar data?

1. Press crew

2. Press office

3. Print buyer

4. Prepress


Customers of the data

1. Press crew

2. Press office

3. Print buyer

4. Prepress

Needs data to run the job well

Familiar with density / dot gain / trap

Hard to use CIELAB


I don't care what they say,

I won’t stay in a

world without color bars.

In a World Without Colorbars,

by Paul McCartney

(made famous by Peter and Gordon)



1. Press crew

2. Press office

3. Print buyer

4. Prepress



Hard to use CIELAB

Press diagnostics


Insurance against customer complaints



1. Press crew

2. Press office

3. Print buyer

4. Prepress



Hard to use CIELAB

Press diagnostics



Proof that job ran properly


Differing viewpoints



1. Press crew

2. Press office

3. Print buyer

4. Prepress



Hard to use CIELAB

Press diagnostics




So… what is needed to prove this?



1. Press crew

2. Press office

3. Print buyer

4. Prepress



Hard to use CIELAB

Press diagnostics




Adjustment of plate curves


Requirements for metrics

Data to run job

Know density / dot gain / trap

Don’t know CIELAB

Press diagnostics

Insurance for complaints

Prove that job correct

Adjust plate curves

Density-based colorbar CIELAB-based in the work


Gap analysis

Data to run job


Don’t know CIELAB

Press diagnostics



Adjust plate curves

Training

Better software



Gap analysis

Dense City

is on an island

Colorimetropolis

is the mainland

Paint

Textiles

Spot colors

Tennis court lighting


Gap analysis

Data to run job


Don’t know CIELAB

Press diagnostics



Adjust plate curves

Better software



Gap analysis

Solid ink density TVI

from the image

We’re working on it…


Gap analysis

Data to run job


Don’t know CIELAB

Press diagnostics



Adjust plate curves Better software



Gap analysis

We’re working on this, too…

US patent 7,032,508

Adjust plate curves


Gap analysis

Data to run job


Don’t know CIELAB

Press diagnostics



Adjust plate curves


Will be taken care of


Cold hearted orb that rules the night

Removes the color bars from our sight

Red is gray and yellow, white

But we decide which is right

And which is an illusion

Nights in White Satin, The Moody Blues


Changes to 12647-3

ISO standard for newspaper printing

Current version requires

CIELAB values of solids and overprints

Tone Value Increase targets


Changes to 12647-3

Latest draft requires one of…

CIELAB values of solids and overprints

Tone Value Increase targets

Target CIELAB values for

CMY gray and K midtone

Some set of measurements from the work

--or--

--or--


ISO 15339-1

All CMYK values

specified in CIELAB

via a characterization data set


Imagine there’s no color bars

It isn’t hard to do

Nothing to adjust your ink keys

to…

Imagine, John Lennon


How to do CCIW?

1. Find the patch in the image

2. Convert RGB to CMYK

3. Tease out black with IR

4. CIELAB optimization

Four methods for color control in the work

From “Closed loop color control in the work”,

Seymour, Tiltman, Nelson, 2010 TAGA


Find the patches in the image

Pseudo-color bar

Method #1


Find the patches in the image

?

Method #1


Convert to CMYK

Capture RGB image

Convert to CMYK

Compare against correct CMYK

US patent 7,040,232

Add up errors

A measurement

at each pixel

of C, M, Y, & K ink

Method #2


Convert to CMYK

Capture RGB image

Convert to CMYK


Add up errors

Is this just standard

color separation?

Color separation finds one

of many possible

combinations of CMYK to

give the RGB value.

CCIW needs to know how

much of each ink is there.

No

Method #2


Convert to CMYK

Test image

Cyan Magenta Yellow Black

Method #2


Convert to CMYK

Capture RGB image

Convert to CMYK


Can’t get

four pieces

of information

from three

Add up errors

Method #2


Tease out black using IR

Black can be seen in IR;

CMY are invisible

Once you know black,

you can take black

out of RGB image

QT patents 5,412,577 and 5,724,259,

Man Roland patent 5,530,656

Goss patent 5,903,712

May be used in other color control systems

Capture RGB+I image

Convert to CMYK


Add up errors

Method #3


RGB+I method

• Requires special camera

• Weighting of errors does not match the

human eye

Method #3


RGB+I method

Tiny changes in C, M, and Y

will cause big visual shifts

Method #3


Methods 1, 2, and 3

Paradigm -

Goal: correct amount of each of the inks

If this is the goal…

you need to measure

the amount of each ink


Methods 1, 2, and 3

Paradigm -

Goal: correct amount of each of the inks

What is the correct amount?

Is it the correct cyan density of a C40

M60?


CIELAB optimization

Alternate paradigm -

Goal: correct color

If this is the goal…

you need to measure

the color

Method #4


All pixels request color change

Target image Live image

Redder

Brighter

More

saturated

Darker

Method #4


Every pixel gets a vote Method #4


CIELAB optimization

Adjust these values

To minimize this

Estimate

and evaluate

color change

DC, DM, DY, DK

Overall DE

Current

L*a*b*

values

Target

L*a*b*

values

US Patent 5,967,050

Method #4


How to do CCIW?

1. Find the patch in the image

2. Convert RGB to CMYK

3. Tease out black with IR

4. CIELAB optimization

Four methods for color control in the work

Target CMYK

amount

Target CIELAB

value


Measuring in the work

1. Image at 300 DPI

2. Image whole web

3. 32 spectral channels

4. Up to 3,000 FPM

5. Really inexpensive

Ideal measurement system



Possible design options

Device Channels DPI All the web?

RGB area

camera

3 300+ DPI No





RGB area

camera

3 300+ DPI No

Point spectro 30+ 1 DPI? Yes, in a spiral





RGB area

camera

3 300+ DPI No


Hyperspectral

linescan

30 2 DPI Yes





RGB or RGB+I

area camera

3 or 4 300+ DPI No


Hyperspectral

linescan

30 2 DPI Yes, in blocks

Six channel

linescan camera

6 25 DPI Yes, in pages


QuadTech AccuCam

300 DPI 25 DPI 6 DPI

Can read text, can see wrinkles

Lost detail, still color faithful

Color starts to suffer


QuadTech AccuCam

Measurement accuracy on 1,296 CMYK patches

95th percentile 1.5 DE94


Summary

• Color bars not always welcome

• Color bars don’t ensure correct image

• Customers of data can be satisfied

• Standards are following

• Various algorithms for CCIW

• Various possible measurement devices


Thanks for listening!

John Seymour

Principal Research Engineer

QuadTech

[email protected]

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