iarigai 2009 printing by the numbers

Printing by the numbers

Petter KolsethLuc Lanat, Örjan Sävborg

Stora EnsoSweden & [email protected]

36th International Research ConferenceStockholm, Sweden

Printing by the numbers on commercial paperPetter Kolseth, Luc Lanat, Örjan Sävborg

September 2009 Printing by the numbers / Kolseth-Lanat-Sävborg 3

Standardised Print


Standardised Print

So where was the Paper Industry…?


Standardised Print – Why Now?

• Fogra offset process standards date back to the 1980’s

• ISO 12647-2 appeared first in 1996• Paper sales was approached by printers only over last couple of years

• Print is moving towards an industrial process


Potential sources for confusion and debate

• "Numbers" in the ISO standards– Paper shade – Primary and secondary colours– Tone Value Increase – tonal transfer

• Measurement conditions and calibration procedures– Paper industry: D65/10°, C/2°, D50/2°– Graphic industry: M0, M1, M2, M3

• Paper fluorescence


Sheet offset on coated woodfreeStandardised Print

• Market follow-up on 50 European papers– Paper Type 1 and 2

• Comparison of 10 inks on three papers – Gloss, silk, matt (Type 1 and 2)

Scanning densitometer Print layoutGretag Spectrolino

Paper shadeLudovic Coppel, Innventia


Print substrate colour and glossISO 12647-2: Offset lithography

• Five typical paper types and their shade/colour and gloss: Paper type L* a* b* gloss1. Gloss-coated, woodfree 93(95) 0(0) -3(-2) 652. Matte-coated, woodfree 92(94) 0(0) -3(-2) 383. Gloss-coated, web 87(92) -1(0) 3(5) 554. Uncoated, white 92(95) 0(0) -3(-2) 65. Uncoated, slightly yellowish 88(90) 0(0) 6(9) 6Tolerance ±3 ±2 ±2 ±5----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

– Black backing to allow for showthrough from reverse printValues in brackets refer to white backingSubstrate backing (white) is standard in paper industry

– D50 illuminant, 2° observer, 0/45 or 45/0 geometryD65/10° or C/2° and d/0° geometry is standard in paper industry


Print substrate used for proofingISO 12647-2: Offset lithography

• Print substrate used for proofing – identical to that of the production• If not possible – close match in colour, gloss, surface grammage• Press proofing on closest match to five typical paper surface types • Proof substrate to conform … to attributes in Table 1 of the paper type

representing the production paper

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Paper type L* a* b* gloss1. Gloss-coated, woodfree 93(95) 0(0) -3(-2) 652. Matte-coated, woodfree 92(94) 0(0) -3(-2) 383. Gloss-coated, web 87(92) -1(0) 3(5) 554. Uncoated, white 92(95) 0(0) -3(-2) 65. Uncoated, slightly yellowish 88(90) 0(0) 6(9) 6Tolerance ±3 ±2 ±2 ±5


-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

-5 -4 -3 -2 -1 0 1 2 3 4 5

CIELAB-a*

CIE

LAB

-b*

Paper shade – Elrepho D65/10°Paper Type 1 – 90-250 gsm

Measurements according to paper industry standard

All products out-of-range


-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

-5 -4 -3 -2 -1 0 1 2 3 4 5

CIELAB-a*

CIE

LAB

-b*

Paper shade – Elrepho D65/10°Paper Type 2 – 90-250 gsm

Measurements according to paper industry standard

All except one products out-of-range


Paper shade – Elrepho C/2°Paper Type 1 – gloss 90-250 gsm

Measurements according to "indoor whiteness" standard

Some products in the box

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

-5 -4 -3 -2 -1 0 1 2 3 4 5

CIELAB-a*

CIE

LAB

-b*


-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

-5 -4 -3 -2 -1 0 1 2 3 4 5

CIELAB-a*

CIE

LAB

-b*

Paper shade – Spectrolino D50/2°Paper Type 1 – 90-250 gsm

Measurements according to printing industry standard

UV content not known

Most products in the box


-9,00

-8,00

-7,00

-6,00

-5,00

-4,00

-3,00

-2,00

-1,00

0,00

0,00 0,50 1,00 1,50 2,00 2,50

CIELAB-a*

CIE

LAB

-b*

Shades of double-coated glossy papers More than 80% would fit into a proposed new recommended range

Presentation WG3TF1 Paper Characterization (Bertholdt, ISO TC130 WG3, Bangkok 2007-05-15)


Paper shade – D65/10° - D50/2° - i1 D50/2°Paper Type 2 – Silk-coated fine paper

-20

-15

-10

-5

0

5

10

15

20

-20 -15 -10 -5 0 5 10 15 20

a*

b*

D50 i1D50 D65

Moderate fluorescence

The D65 UV setting high enough to offset the b*


Paper shade – D65/10° - D50/2° - i1 D50/2°Paper Type 3 – Uncoated fine paper

-20

-15

-10

-5

0

5

10

15

20

-20 -15 -10 -5 0 5 10 15 20

a*

b*

D50 i1D50 D65

Strong fluorescence

The D65 UV setting gives even larger offset in b*


Paper shade – D65/10° - D50/2° - i1 D50/2°Paper Type 4 – Uncoated WoodFree without OBA

-20

-15

-10

-5

0

5

10

15

20

-20 -15 -10 -5 0 5 10 15 20

a*

b*

D50 i1D50 D65

No fluorescence

D65 and D50 quite close, but D50 slightly more red

Conclusions – Paper Shade

A matter of taste – forget "ISO compliant"

ISO does not specify allowed shades

Should be determined with dedicated equipment

Most papers are within a narrow range of shades

Primaries and SecondariesAndreas Paul, FOGRA


Colour gamut – Spectrolino D50/2°Paper Type 1 and 2, gloss/matt/silk 90-250

-100

-80

-60

-40

-20

0

20

40

60

80

100

-100 -80 -60 -40 -20 0 20 40 60 80 100

a*-a*

-b*

b*GlossMatt/Silk

Target valuesAll prints rather close to target colour CMYRGBOriginal RGB targets


Colour gamut – Spectrolino D50/2°Paper Type 1 and 2, gloss/matt/silk 90-250

-100

-80

-60

-40

-20

0

20

40

60

80

100

-100 -80 -60 -40 -20 0 20 40 60 80 100

a*-a*

-b*

b*All prints very close to target colour CMYRGBAfter the 2004 Amendment


Ten inks on gloss, silk and matt paperColour gamut – Elrepho C/2°

-100

-80

-60

-40

-20

0

20

40

60

80

100

-100 -80 -60 -40 -20 0 20 40 60 80 100

CIE a*CIE -a*

CIE b*

CIE -b*

Ten inks on Gloss paperTen inks on Silk paperTen inks on Matt paper 30 ink-paper

combinations but almost identical results

Conclusions – Primaries and Secondaries

No (or very small) influence of paper brand

Target colours can be reached with standard inks

Paper fluorescenceLudovic Coppel, Innventia


Fluorescence – CIE Whiteness (D65)

Gloss-Coated 200 – 350 gsm

10

20

30

40

50

60

70

100 110 120 130 140 150

CIE Whiteness (D65/10°)

Fluo

resc

ence

(D65

/10°

)


CIE Whiteness – CIELAB-b* (D65)

Gloss-Coated 200 – 350 gsm

100

110

120

130

140

150

-14 -12 -10 -8 -6 -4 -2 0

CIELAB-b* (D65/10°)

CIE

Whi

tene

ss (D

65/1

0°)


Primaries and Secondaries – Elrepho D65/10°Paper Type 2 – Silk-coated fine paper

-60

-40

-20

0

20

40

60

80

100

-80 -60 -40 -20 0 20 40 60 80

a*

b*

Elrepho D65/10°


Primaries and Secondaries – i1 D50/2°Paper Type 2 – Silk-coated fine paper

-60

-40

-20

0

20

40

60

80

100

-80 -60 -40 -20 0 20 40 60 80

a*

b*


Primaries and Secondaries – D50/2°Paper Type 2 – Silk-coated fine paper

-60

-40

-20

0

20

40

60

80

100

-80 -60 -40 -20 0 20 40 60 80

a*

b*

Elrepho D50/2°


Primaries and Secondaries – D50/2° UV excludedPaper Type 2 – Silk-coated fine paper

-60

-40

-20

0

20

40

60

80

100

-80 -60 -40 -20 0 20 40 60 80

a*

b*

Elrepho D50/2° UV excluded


Spectral power and Relative UV contentIlluminants D65, C, D50, A

0

50

100

150

200

250

300

350 400 450 500 550 600 650 700 750

Wavelength, nm

Spec

tral P

ower

D65 C D50 A

Relative to 560 nm (max colour vision)

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

340 360 380 400 420 440 460 480 500 520 540 560

Wavelength, nm

Spec

tral P

ower

D65rel Crel D50rel Arel

Relative to 440 nm fluorescence peak

Relative power of A is almost twice that of C between 340 and 380 nm


Illumination is NOT same as Illuminant Illumination 5000K and Illuminant D50

Ludovic Coppel, Innventia, 2008300 350 400 450 500 550 600 650 700 7500

0,5

1

1,5

2

Wavelength (nm)

Rel

ativ

e Po

wer

D50D655000K CCT5000K CCT + UV

300 350 400 450 500 550 600 650 700 7500

0,5

1

1,5

2

Wavelength (nm)

Rel

ativ

e Po

wer




-14,0

-12,0

-10,0

-8,0

-6,0

-4,0

-2,0

0,0

2,0

4,0

6,0

-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0

CIELAB-a*

CIE

LAB

-b*

Proof substrates from one supplierx-rite iOne – a*-b* data

Red symbols denote certified proof substrates

Green symbols denote production paper PT2 and PT4

Type 2

Type 4

Conclusions – Paper Fluorescence

Fluorescence make papers whiter (more blue)

Effect is very dependent on illumination

Fluorescence shines through all print

Matching proof to print with proper choice of proof substrate and illumination

Tone Value Increase


Tone Value Increase: Black and CyanPaper Type 1 – 90-250 gsm

Black and Cyan Dot Gain are both within tolerance

0%

5%

10%

15%

20%

25%

30%

0% 20% 40% 60% 80% 100%

Nominal tone

Bla

ck T

one

Valu

e In

crea

se

20% +/- 4

0%

5%

10%

15%

20%

25%

30%

0% 20% 40% 60% 80% 100%

Nominal tone

Cya

n To

ne V

alue

Incr

ease

20% +/- 4


Optical dot gainEffect on tone value and colour

after Matthieu Bossan, Creo, 2002

AM

FM


Reflectance histograms of K100, K40 and paper white13,2% TVI(40)

0,0

0,5

1,0

1,5

2,0

2,5

0 20 40 60 80 100

Reflectance, %

Freq

uenc

y, %

0,0

5,0

10,0

15,0

20,0

25,0

<K40> <BLACK> <WHITE>



0,0

0,5

1,0

1,5

2,0

2,5

0 20 40 60 80 100

Reflectance, %

Freq

uenc

y, %

0,0

5,0

10,0

15,0

20,0

25,0



0,0

0,5

1,0

1,5

2,0

2,5

0 20 40 60 80 100

Reflectance, %

Freq

uenc

y, %

0,0

5,0

10,0

15,0

20,0

25,0



Solid black

Halftone dots Between dots

Unimaged paper


0,0

0,5

1,0

1,5

2,0

2,5

0 20 40 60 80 100

Reflectance, %

Freq

uenc

y, %

0,0

5,0

10,0

15,0

20,0

25,0



Solid black

Halftone dots

Between dots

Unimaged paper


Black halftone seen in the microscope


Thresholding between peaks in histogram


Tone Value comparisonDensitometer readings vs. microscopy

46

48

50

52

54

56

50 52 54 56 58 60 62 64

Densitometer Tone Value

Mic

rosc

opy

Tone

Val

ue


0,0

2,0

4,0

6,0

8,0

10,0

-20 -15 -10 -5 0

Reduction in paper reflectance between dots

Opt

ical

TVI

Optical Tone Value Increase Tone Values by microscopy

Single-coat matt

multicoat gloss multicoat silk

Conclusions – Tone Value Increase

Mechanical TVI is small (in the ideal case)

Optical TVI is quite large

Optical TVI is an inherent paper property (but not related to brand)

TVI variations are mechanical due to press settings

What is next?

Luc LANAT Stora Enso PrintNet at iarigai Stockholm Sept 2009


Optics – What next?

• To define (White) Paper shade targets– Use ISO 5631-1 or 2 Colour L*a*b* C/2° or D65/10°

• ISO 13655-2009 must not be used to specify (white) papers– Use ISO 5631-3 Colour L*a*b* D50/2°

• To evaluate Fluorescence in papers– Use ISO 2470-2 (Note 8.4) on D65 Brightness– Use ISO 11476 (Note 10.3), ISO 11475 (Clause 10.3). Whiteness

• Organize UV calibration of D50 illuminant is a MUST


Dot Gain – TVI

• ISO TS 10128-2008 « Methods of adjustment of the colour reproduction of a printing system to match a set of characterisation data »

– When measuring quality of a print thru reflectance, you are indeed integrating all variations, variations coming from base, thus paper, variations coming from inks, from press, etc…

– To define Dot Gain or TVI of a paper is a misunderstanding


Standardization – What next?

• There is no ISO compliant paper– See Paperdam statement Sept 2009– We recommend publicly available colour profiles and

characterization data (ECI, PSR, FOGRA…)

• ISO TC 6 Berlin, support creation of NWI– Develop ISO 5630-7, aging under light conditions to evaluate light

fastness– Develop D 50 UV calibration rules

• ISO TC 130 Beijing, support creation of NWI– How to measure proof papers– JWG (joint working group) liaison TC 6 – TC 130


The last slide – 3 points

• The daily challenge in a paper mill is to fulfil paper specifications communicated in Technical Data Sheets, in this order

– Brightness and shade– Smoothness (PPS,…)– Gloss– Anything to satisfy printing results at printer

• Process Management at printer and at papermaker is the topic– For a given grade, work on process consistency and not on

upgrade of paper definition to reach better printed results

• It is common interest of all players in this market to help standardization and support quality of printed media at lowest cost

Thank You

iarigai 2009 printing by the numbers

Technology

production paper

numbers kolsethlanat

paper typel

paper typerepresenting

paper sales

innventia paper shade

paper shade d6510 d502

uncoated fine paper