Graphic technology — Process control for the production of half-tone colour separations, proofs and production prints — Part 3: Coldset offset lithography on newsprint

ISO 12647-3:2013 specifies a number of process parameters and their values to be applied when producing colour separations and printing forms for newspaper single or four-colour printing. The parameters and values are chosen in consideration of the process, covering the process stages: "colour separation", "making of the printing formed", "OK print or proof" and "production printing". ISO 12647-3:2013 is intended to enhance communication between printers, publishers and advertisers and to make print buyers aware of the expected printed result in advance, enabling them to plan accordingly. ISO 12647-3:2013 defines tolerances, allowing for objective quality evaluations and raising the competitiveness of newspapers compared to other media. ISO 12647-3:2013 is applicable: to coldset offset production printing on newsprint that use colour separation data; by analogy to press printing from printing surfaces produced by direct imaging; to line screens and non-periodic screens, parameters given can be applied by analogy.

Technologie graphique — Contrôle du processus de confection de sélections couleurs tramées, d'épreuves et de tirages — Partie 3: Impression offset sans sécheur sur papier journal

Grafična tehnologija - Vodenje procesa izdelave rastriranih barvnih izvlečkov, preskusnih in proizvodnih odtisov - 3. del: Procesi v časopisnem ofsetnem tisku na rotacijah s hladnim sušenjem

General Information

Status
Published
Publication Date
11-Dec-2013
Current Stage
9093 - International Standard confirmed
Start Date
05-Mar-2019
Completion Date
05-Mar-2019

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INTERNATIONAL ISO
STANDARD 12647-3
Third edition
2013-12-15
Corrected version
2014-02-15
Graphic technology — Process control
for the production of half-tone colour
separations, proofs and production
prints —
Part 3:
Coldset offset lithography on
newsprint
Technologie graphique — Contrôle du processus de confection de
sélections couleurs tramées, d’épreuves et de tirages —
Partie 3: Impression offset sans sécheur sur papier journal
Reference number
ISO 12647-3:2013(E)
ISO 2013
---------------------- Page: 1 ----------------------
ISO 12647-3:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 12647-3:2013(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Requirements .......................................................................................................................................................................................................... 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Data files and printing forms ...................................................................................................................................................... 2

4.3 Proof or production print .............................................................................................................................................................. 4

5 Test methods ..........................................................................................................................................................................................................12

5.1 Computation of CIELAB colour coordinates and CIELAB colour differences ................................12

5.2 Control strip ...........................................................................................................................................................................................12

Annex A (informative) Densities of ink set colours ............................................................................................................................13

Annex B (informative) Grey reproduction and grey balance ...................................................................................................14

Annex C (informative) Process control targets .......................................................................................................................................17

Annex D (informative) Flexographic newspaper printing ..........................................................................................................18

Annex E (informative) Additional printing conditions ...................................................................................................................19

Annex F (informative) Handling differences in paper colour ..................................................................................................22

Bibliography .............................................................................................................................................................................................................................23

© ISO 2013 – All rights reserved iii
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ISO 12647-3:2013(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 130, Graphic technology.

This third edition cancels and replaces the second edition (ISO 12467-3:2005), which has been revised

due to demands from customer experience. The revision introduces grey reproduction and grey balance

calculation, a printing condition for standard newsprint, normative ΔE* tolerances for primary and

secondary colours, one general tone value increase curve, a change in the colouration of magenta, options

to monitor the printing characteristics and a general clean up.

ISO 12647 consists of the following parts, under the general title Graphic technology — Process control

for the production of half-tone colour separations, proof and production prints:
— Part 1: Parameters and measurement methods
— Part 2: Offset lithographic processes
— Part 3: Coldset offset lithography on newsprint
— Part 4: Publication gravure printing
— Part 5: Screen printing
— Part 6: Flexographic printing
— Part 7: Proofing processes working directly from digital data
— Part 8: Validation print processes working directly from digital data

This corrected version of ISO 12647-3:2013 incorporates the following corrections:

— in 4.2.8, a formatting error in the second paragraph has been corrected;

— in Annex F, the word “might” has been changed to “may” in the first sentence of the first paragraph.

iv © ISO 2013 – All rights reserved
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ISO 12647-3:2013(E)
Introduction

When producing a half-tone colour reproduction it is important that the colour separator and printer

have previously specified a minimum set of parameters that uniquely define the visual characteristics

and other technical properties of the planned print product. Such an agreement enables the correct

production of suitable separations (without recourse to “trial-and-error”).
For more information on the technical background refer to ISO 12647-1.

It is the purpose of this part of ISO 12647 to list and explain the minimum set of process parameters

required to uniquely define the visual characteristics and related technical properties of a half-tone

production print produced by coldset offset lithography on newsprint from a set of half-tone separation

data.

It is a further purpose of this part of ISO 12647 to list values or sets of values of the primary parameters

specified in ISO 12647-1 and related technical properties of a half-tone newspaper print produced

from a set of half-tone colour separation data. When deemed useful, secondary parameters are also

recommended for specification.
Provisions for flexographic printing can be found in informative Annex D.
© ISO 2013 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 12647-3:2013(E)
Graphic technology — Process control for the production
of half-tone colour separations, proofs and production
prints —
Part 3:
Coldset offset lithography on newsprint
1 Scope

This part of ISO 12647 specifies a number of process parameters and their values to be applied when

producing colour separations and printing forms for newspaper single or four-colour printing. The

parameters and values are chosen in consideration of the process, covering the process stages: “colour

separation”, “making of the printing formed”, “OK print or proof” and “production printing”.

This part of ISO 12647 is intended to enhance communication between printers, publishers and

advertisers and to make print buyers aware of the expected printed result in advance, enabling them to

plan accordingly. This part of ISO 12647 defines tolerances, allowing for objective quality evaluations

and raising the competitiveness of newspapers compared to other media.
This part of ISO 12647 is applicable:

— to coldset offset production printing on newsprint that use colour separation data;

— by analogy to press printing from printing surfaces produced by direct imaging;

— to line screens and non-periodic screens, parameters given can be applied by analogy.

Although this International Standard does not specify process control for flexographic printing, digital

printing systems or letterpress production printing, the production aims defined by this International

Standard may be applied when these printing technologies are used and where the printing result is

intended to be similar to that produced by coldset offset lithography.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 5-3, Photography and graphic technology — Density measurements — Part 3: Spectral conditions

ISO 2846-2, Graphic technology — Colour and transparency of printing ink sets for four-colour printing —

Part 2: Coldset offset lithographic printing

ISO/TS 10128, Graphic technology — Methods of adjustment of the colour reproduction of a printing system

to match a set of characterization data

ISO 12647-1:2013, Graphic technology — Process control for the production of half-tone colour separations,

proof and production prints — Part 1: Parameters and measurement methods

ISO 12647-7, Graphic technology — Process control for the production of half-tone colour separations, proof

and production prints — Part 7: Proofing processes working directly from digital data

ISO 13655:2009, Graphic technology — Spectral measurement and colorimetric computation for graphic

arts images
© ISO 2013 – All rights reserved 1
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ISO 12647-3:2013(E)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 12647-1 and the following

apply.
3.1
coldset offset lithography

method of offset lithographic printing (conventional or waterless) where the inks set “dry” primarily by

absorption into the print substrate
3.2
digital proof print

digital print of high colour accuracy, useable as reliable visual colour reference for printing, and as a part

of a commercial agreement as defined in ISO 12647-7
4 Requirements
4.1 General

Digital data files delivered for printing should be accompanied by a digital proof print, a press proof print,

or an OK print from a previous print run. An OK-print from a previous print run (or a press proof), being

in conformance with the requirements for an OK-print stipulated in 4.3 and stored under appropriate

conditions, shall be used as the reference for the OK-print.

Digital proofs using an electronic display and digital proof prints shall not be used to gather measurement

values to be used as reference in this part of ISO 12647.

NOTE On-press proof prints are test prints of the data files on a printing press. Most proofs are digital proof

prints. However, for colour or content critical work sometimes there is a request for press proof prints using the

same setup as the production print.
4.2 Data files and printing forms
4.2.1 Data files

Data delivered for printing shall be in the colour formats CMYK or three components and should be

exchanged in PDF/X data formats as defined in ISO 15930 (all parts).

The intended printing condition shall be indicated in case of PDF/X data exchange. In case of PDF/X

the mechanisms provided by the specified data format shall be used. In case of other data formats, a

printing condition description, a characterization data set, or an International Colour Consortium (ICC)

output profile shall be communicated.

Data other than CMYK shall be defined by colorimetric description using an ICC profile or other

mechanism. An ICC CMYK output profile should be included. The rendering intent to be used with the

output profile shall be communicated.

If the characterization data or ICC output profile provided conflict with the printing conditions defined

in this part of ISO 12647 one of the methods defined in ISO/TS 10128 shall be used for data adjustment

toward the printing conditions defined in this International Standard.

Checks are recommended to ensure the conformance of the data with the requirements of the printing

standard.
4.2.2 Printing form quality

The resolution of the plate setter shall be set to a minimum frequency of 393cm and should be set to a

minimum frequency of 500cm .
2 © ISO 2013 – All rights reserved
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ISO 12647-3:2013(E)

The deviation of similar tone values of the data file in different areas of the printing form shall not

exceed ± 1,5 tone value %.
4.2.3 Screen frequency (periodic screens)
−1 −1

For all half-tone elements, the screen frequency should be between 40 cm and 54 cm . Within the

same print product the screen ruling shall be the same for colour and black-and-white printing. If other

screen rulings are used the tone value increase shall be adjusted such that it agrees with Table 7 and

Figure 3.

NOTE 1 Older Raster Image Processor (RIP) software might not be able to produce the requested screen angle

at the requested screen ruling exactly. This is why with computer-generated screens, the parameters screen

ruling and screen angle can be varied slightly.

NOTE 2 Screen frequencies are often required or given in lpi (lines per inch). To convert between lines per

centimetre and lines per inch a conversion factor of 2,54 should be used. For example the requirement of 40 and

54 given in lpi will read as follows (rounded to commonly used integral numbers): for all half-tone elements, the

screen frequency should be between 100 lpi and 140 lpi.
4.2.4 Screen dot size (non-periodic screens)

The screen dot size for non-periodic screens should be 40 µm ± 10 µm, depending on substrate

requirements.
4.2.5 Screen angle (periodic screens)

For half-tone dots without a principal axis, the nominal difference between the screen angles for cyan,

magenta and black should be 30°, with the screen angle of yellow separated at 15° from another colour.

The screen angle of the dominant colour should be 45°. The dominant colour is defined as the one that

contains most of the image information compared to the others. For typical newspaper applications

the dominant colour will be black. Refer to Figure 1 for an example of a screen angle combination for a

screen with a principal axis and with black as the dominant colour.

For half-tone dots with a principal axis (elliptical half-tone dot shape), the nominal difference between

screen angles for cyan, magenta and black should be 60°, with the screen angle of yellow at 0° and 15° off

from the next screen angle. The screen angle of the dominant colour should be 45° or 135°.

Figure 1 — Example of a screen angle combination for a screen with a principal axis and with

black as the dominant colour

NOTE The dominant colour is defined as that which contains most of the image information compared to the

others. For typical newspaper colour separations with GCR the dominant colour will be black.

© ISO 2013 – All rights reserved 3
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ISO 12647-3:2013(E)
4.2.6 Dot shape and its relationship to tone value (periodic screens)

For periodic screens, elliptical half-tone dot shapes should be used. For half-tone dots with a principal

axis, the first link-up should occur no lower than at 40 % tone value (data) and the second link-up no

higher than at 60 % tone value (data).
4.2.7 Tone value sum

Unless otherwise specified, the tone value sum should not exceed 220 % and shall not exceed 240 %.

Where the maximum tone value sum approaches this limit, the tone value of black should be at least

90 %.

NOTE Any colour that is reproduced using all three chromatic process inks can be thought of as having a

neutral component. This is defined by the lowest tone value and its grey balance equivalents of the other two

inks. It is possible to replace all or some of the neutral component by black ink. Under colour removal (UCR) limits

the tone value sum by replacing chromatic colour ink with black ink in the neutral shadows. Grey component

replacement (GCR) replaces chromatic colour ink with black ink in the entire colour space. GCR is recommended

for newspaper colour separations because it reduces colour variations caused by poor ink trapping, back transfer,

set-off during the print run, and eases registration.
4.2.8 Grey reproduction and grey balance

The grey balance in printing can effectively be used for print quality control in newspaper print

production. Since typical newsprint does not have a neutral but a yellowish colour, the following

calculation method of grey balance in printing should be applied for coldset printing.

The tone values of cyan, magenta and yellow leading to a visually neutral grey should be calculated from

the standard printing condition or actual printing condition or the associated profiles by the following

formula describing the grey reproduction La*, *,b* with respect to a given paper colour

La*, *,b* and CMY-overprint L* for each L* in the range from L* to
() ()
paper paper paper cmy paper
L* :
cmy
 
aa**=× 10−×,*85 LL− */ LL**−
() ()
paper paper papercmy
 
 
bb**=× 10−×,*85 LL− */ LL**−
() ()
paper paper papercmy
 

NOTE 1 A single grey balance condition is usually not sufficient to ensure an achromatic colour for all print

substrates and printing inks that may be used with a given printing process. Therefore the grey balance has to be

determined for each printing condition separately based on a well-defined grey reproduction.

NOTE 2 The grey balance of a given printing process can be used for process calibration and process control as

long as the tolerances for tone value increase and mid-tone spread as defined in Table 7 are not exceeded.

NOTE 3 The multiplying factor of 0,85 represents a visual adaptation of 85 % to the paper white.

NOTE 4 See Annex B for more information on specifying grey balance values.
4.3 Proof or production print
4.3.1 General

A printing condition for coldset offset printing shall be described by a print substrate, a colorant

description, a screening description, an ink set, and a printing sequence. In all printing conditions

described in this part of ISO 12647, the ink set shall be according to ISO 2846-2 and the printing

sequence shall be Cyan – Magenta – Yellow – Black or Black - Cyan – Magenta – Yellow. See specifications

4 © ISO 2013 – All rights reserved
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ISO 12647-3:2013(E)

of printing conditions for typical print substrates in Table 1. See Annex E for information on additional

printing conditions.

NOTE 1 Characterization data are based on CMYK which is generally the preferred printing sequence.

Table 1 — Printing conditions for typical print substrates
Screening description
Print substrate Colorant
Printing
description description Periodic screens Non-periodic screens
condition
(Table 2) (Table 3)
TVI Frequency TVI Spot size
40 cm
Offset Standard newsprint SNP 26 % 26 % 40 µm
to 54 cm

Colorimetric characterization data, as specified in ISO 12642, contain all the data to be specified in

accordance with 4.3.2.1, 4.3.2.3 and 4.3.4.1

NOTE 2 Additional printing conditions based on commonly used print substrates may follow the scheme

described in this and the following clauses.

NOTE 3 Table 1 does not define a paper specification but is intended to give an indication of a reference on

which the target colours can be reached.
4.3.2 Visual characteristics of image components
4.3.2.1 Print substrate colour

The production print substrate shall conform to the L*, a*, b* values and tolerances specified in Table 2.

A digital proof on an electronic display or a digital proof print according to ISO 12647-7 produced

directly from digital data should be used as a visual reference. Press proof printing should be carried

out using a substrate, which matches as closely as possible all of the properties listed in Table 2. For off-

press proofing, the requirements defined in ISO 12647-7 apply. A paper selection in the light of a close

simulation with respect to the aim values defined in Table 2 ensures an easy simulation of the associated

colorant description and therefore the visual appearance.
© ISO 2013 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 12647-3:2013(E)

Table 2 — CIELAB coordinates, mass-per-area, gloss, and CIE whiteness for typical print

substrates
Parameters Print substrate
Characteristic Standard newsprint
Type of surface Uncoated
g/m
Mass-per-area (informative only)
40 to 52 (45)
Brightness C (informative only)
55 to 80
Gloss (informative only)
< 5
Colour
Parameters L* a* b*
White backing (informative only) 85 1 5
Black backing 82 0 3
Tolerance ±4 ±2 ±2
a, b, c
Informative only. A bandwidth of typical values (product properties) applies.

Mass-per-area: values in brackets pertain to the respective colour coordinates (influence of white or black backing).

Measurement is in accordance with ISO 2470-1, ISO brightness.
Measurement is in accordance with ISO 8254-1, TAPPI method.

Measurement is in accordance with ISO 13655-D50 illuminant, 2° observer, 45:0 or 0:45 geometry. Experts of the paper

making industry usually use different measuring conditions. They measure according ISO 2469: C illuminant 2 observer,

d/0° geometry, opaque pad of newsprint backing. Under ISO 2469 conditions and according ISO 5631-1 the following colour

values correspond to the colour coordinates of this table: L* 83,4 / a* -0,3 / b* 5.

NOTE 1 Annex F gives more information on handling differences in paper colour.

NOTE 2 Table 2 does not define a paper specification but is intended to give an indication of a reference on

which the target colours can be reached.
4.3.2.2 Print substrate gloss

The gloss of the print substrate used for press proof printing should be a close simulation to that of the

production print substrate. Matching the gloss of the print substrate is also important for digital proof

printing stipulated in ISO 12647-7.
NOTE Information on gloss values is given in Table 2.
4.3.2.3 Ink set colours (colorant description)

The CIELAB colour coordinates L*, a*, b* of the process colour solids CMYK and the secondary colour

overprints Red (M+Y), Green (C+Y), Blue (C+M) on the OK print shall agree with the aim values specified

in Table 3 within the deviation tolerances specified in Tables 5 and 6. Table 4 specifies the aim values of

ink colours on newsprint measured on white backing and is informative only.

The variability of the process colour solids CMYK during the production run is restricted by the following

condition. For at least 68 % of the prints, the colour differences from the OK print shall not exceed the

appropriate variation tolerances specified in Tables 5 and 6.

At least 68 % of the print production shall follow the conditions expressed in 4.3.2.3, 4.3.4.2 and 4.3.5.

6 © ISO 2013 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 12647-3:2013(E)

Table 3 — CIELAB L*, a*, b* aim values of ink colours on newsprint black backing measurements

(normative)
Colour L* a* b*
Unit 1 1 1
Cyan 57 −23 −27
Magenta 54 44 −1
Yellow 78 −3 58
Black 36 1 4
Cyan + yellow 53 −34 17
Cyan + magenta 41 7 −22
Magenta + yellow 52 41 25
Cyan + magenta + yellow 40 0 1
Four-colour black; (K = 100 %, C = 52 %, M = 44 %,
34 1 2
Y = 44 %)

These values are aim values for the (dry) print product delivered to the customer. Measurements should be made using M1,

in accordance with ISO 13655-D50 illuminant, 2° observer, 45:0 or 0:45 geometry. Values for four-colour black are based on

colour sequence CMYK in printing.

Table 4 — CIELAB L*, a*, b* aim values of ink colours on newsprint white backing measurements

(informative only)
Colour L* a* b*
Unit 1 1 1
Cyan 59 −24 −27
Magenta 56 48 1
Yellow 80 −1 62
Black 37 1 4
Cyan + yellow 55 −34 17
Cyan + magenta 42 7 −23
Magenta + yellow 54 45 26
Cyan + magenta + yellow 40 0 0
Four-colour black; (K = 100 %, C = 52 %, M = 44 %,
35 0 2
Y = 44 %)

These values are aim values for the (dry) print product delivered to the customer. Measurements should be made using M1,

in accordance with ISO 13655-D50 illuminant, 2° observer, 45:0 or 0:45 geometry. Values for four-colour black are based on

colour sequence CMYK in printing.

NOTE 1 The secondary colours red, green, blue can vary depending on conditions that include the mechanics

of the press, the surface characteristics of the print substrate and the rheological and transparency properties of

the inks. Thus, conformance of the primaries C, M, Y to specifications is not sufficient for the conformance of the

secondaries to the values given in Tables 3 and 4.

NOTE 2 The values in Table 3 and Table 4 relate to printing with ink sets in accordance with ISO 2846-2; they

were derived from press runs in the field.

NOTE 3 The distribution of CIELAB values is not Gaussian but skewed. For reasons of consistency, the variation

tolerance is defined here as the upper limit for 68 % of the production copies. This is in analogy with a Gaussian

distribution where 68 % are within plus or minus one standard deviation from the mean.

NOTE 4 As a secondary reference, reflection densities for the process colours as measured with two different

[3] [6]

densitometer types are provided in Annex A. In and a reference to a complete list of X, Y, Z and CIELAB values

of a complete ISO 12642 target is given.
© ISO 2013 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 12647-3:2013(E)

Figure 2 shows the CIELAB L*, a*, b* black backing aim values of ink colours on newsprint (SNP).

Figure 2 — CIELAB L*, a*, b* aim values (bb) of ink colours on newsprint

The variation tolerance is defined as the upper limit for 68 % of the production copies.

Table 5 — CIELAB ΔE* tolerances for the solids of the process colour
Colour deviation Black Cyan Magenta Yellow
Unit 1 1 1 1
Deviation tolerance DE76,
5 5 5 5
normative
Variation tolerance DE76,
4 4 4 5
normative
Deviation tolerance DE2000,
5 3,5 3,5 3,5
informative only
Variation tolerance DE2000,
4 2,8 2,8 3,5
informative only
NOTE Deviation and variation tolerances are defined in ISO 12647-1.
8 © ISO 2013 – All rights reserved
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ISO 12647-3:2013(E)
Table 6 — CIELAB ΔE* tolerances for the secondary colour overprints
Colour deviation M+Y C+Y C+M
Unit 1 1 1
Deviation tolerance DE76,
8 8 8
normative
Variation tolerance DE76,
7 7 7
normative
Deviation tolerance DE2000,
5,6 5,6 5,6
informative only
Variation tolerance
4,9 4,9 4,9
DE2000, informative only
NOTE Deviation and variation tolerances are defined in ISO 12647-1.
4.3.3 Tone value reproductio
...

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Graphic technology - Process control for the production of half-tone colour separations,

proofs and production prints - Part 3: Coldset offset lithography on newsprint

Technologie graphique - Contrôle du processus de confection de sélections couleurs

tramées, d'épreuves et de tirages - Partie 3: Impression offset sans sécheur sur papier

journal
Ta slovenski standard je istoveten z: ISO 12647-3:2013
ICS:
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
SIST ISO 12647-3:2014 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 12647-3:2014
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SIST ISO 12647-3:2014
INTERNATIONAL ISO
STANDARD 12647-3
Third edition
2013-12-15
Graphic technology — Process
control for the production of half-
tone colour separations, proofs and
production prints —
Part 3:
Coldset offset lithography on newsprint
Technologie graphique — Contrôle du processus de confection de
sélections couleurs tramées, d’épreuves et de tirages —
Partie 3: Impression offset sans sécheur sur papier journal
Reference number
ISO 12647-3:2013(E)
ISO 2013
---------------------- Page: 3 ----------------------
SIST ISO 12647-3:2014
ISO 12647-3:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
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Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Requirements .......................................................................................................................................................................................................... 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Data files and printing forms ...................................................................................................................................................... 2

4.3 Proof or production print .............................................................................................................................................................. 4

5 Test methods ..........................................................................................................................................................................................................12

5.1 Computation of CIELAB colour coordinates and CIELAB colour differences ................................12

5.2 Control strip ...........................................................................................................................................................................................12

Annex A (informative) Densities of ink set colours ............................................................................................................................13

Annex B (informative) Grey reproduction and grey balance ...................................................................................................14

Annex C (informative) Process control targets .......................................................................................................................................17

Annex D (informative) Flexographic newspaper printing ..........................................................................................................18

Annex E (informative) Additional printing conditions ...................................................................................................................19

Annex F (informative) Handling differences in paper colour ..................................................................................................22

Bibliography .............................................................................................................................................................................................................................23

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Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 130, Graphic technology.

This third edition cancels and replaces the second edition (ISO 12467-3:2005), which has been revised

due to demands from customer experience. The revision introduces grey reproduction and grey balance

calculation, a printing condition for standard newsprint, normative ΔE * tolerances for primary and

secondary colours, one general tone value increase curve, a change in the colouration of magenta, options

to monitor the printing characteristics and a general clean up.

ISO 12647 consists of the following parts, under the general title Graphic technology — Process control

for the production of half-tone colour separations, proof and production prints:
— Part 1: Parameters and measurement methods
— Part 2: Offset lithographic processes
— Part 3: Coldset offset lithography on newsprint
— Part 4: Publication gravure printing
— Part 5: Screen printing
— Part 6: Flexographic printing
— Part 7: Proofing processes working directly from digital data
— Part 8: Validation print processes working directly from digital data
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Introduction

When producing a half-tone colour reproduction it is important that the colour separator and printer

have previously specified a minimum set of parameters that uniquely define the visual characteristics

and other technical properties of the planned print product. Such an agreement enables the correct

production of suitable separations (without recourse to “trial-and-error”).
For more information on the technical background refer to ISO 12647-1.

It is the purpose of this part of ISO 12647 to list and explain the minimum set of process parameters required

to uniquely define the visual characteristics and related technical properties of a half-tone production print

produced by coldset offset lithography on newsprint from a set of half-tone separation data.

It is a further purpose of this part of ISO 12647 to list values or sets of values of the primary parameters

specified in ISO 12647-1 and related technical properties of a half-tone newspaper print produced

from a set of half-tone colour separation data. When deemed useful, secondary parameters are also

recommended for specification.
Provisions for flexographic printing can be found in informative Annex D.
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INTERNATIONAL STANDARD ISO 12647-3:2013(E)
Graphic technology — Process control for the production of
half-tone colour separations, proofs and production prints —
Part 3:
Coldset offset lithography on newsprint
1 Scope

This part of ISO 12647 specifies a number of process parameters and their values to be applied when

producing colour separations and printing forms for newspaper single or four-colour printing. The

parameters and values are chosen in consideration of the process, covering the process stages: “colour

separation”, “making of the printing formed”, “OK print or proof” and “production printing”.

This part of ISO 12647 is intended to enhance communication between printers, publishers and

advertisers and to make print buyers aware of the expected printed result in advance, enabling them to

plan accordingly. This part of ISO 12647 defines tolerances, allowing for objective quality evaluations

and raising the competitiveness of newspapers compared to other media.
This part of ISO 12647 is applicable:

— to coldset offset production printing on newsprint that use colour separation data;

— by analogy to press printing from printing surfaces produced by direct imaging;

— to line screens and non-periodic screens, parameters given can be applied by analogy.

Although this International Standard does not specify process control for flexographic printing, digital

printing systems or letterpress production printing, the production aims defined by this International

Standard may be applied when these printing technologies are used and where the printing result is

intended to be similar to that produced by coldset offset lithography.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 5-3, Photography and graphic technology — Density measurements — Part 3: Spectral conditions

ISO 2846-2, Graphic technology — Colour and transparency of printing ink sets for four-colour printing —

Part 2: Coldset offset lithographic printing

ISO/TS 10128, Graphic technology — Methods of adjustment of the colour reproduction of a printing system

to match a set of characterization data

ISO 12647-1:2013, Graphic technology — Process control for the production of half-tone colour separations,

proof and production prints — Part 1: Parameters and measurement methods

ISO 12647-7, Graphic technology — Process control for the production of half-tone colour separations, proof

and production prints — Part 7: Proofing processes working directly from digital data

ISO 13655:2009, Graphic technology — Spectral measurement and colorimetric computation for

graphic arts images
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3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 12647-1 and the following apply.

3.1
coldset offset lithography

method of offset lithographic printing (conventional or waterless) where the inks set “dry” primarily by

absorption into the print substrate
3.2
digital proof print

digital print of high colour accuracy, useable as reliable visual colour reference for printing, and as a part

of a commercial agreement as defined in ISO 12647-7
4 Requirements
4.1 General

Digital data files delivered for printing should be accompanied by a digital proof print, a press proof print,

or an OK print from a previous print run. An OK-print from a previous print run (or a press proof), being

in conformance with the requirements for an OK-print stipulated in 4.3 and stored under appropriate

conditions, shall be used as the reference for the OK-print.

Digital proofs using an electronic display and digital proof prints shall not be used to gather measurement

values to be used as reference in this part of ISO 12647.

NOTE On-press proof prints are test prints of the data files on a printing press. Most proofs are digital proof

prints. However, for colour or content critical work sometimes there is a request for press proof prints using the

same setup as the production print.
4.2 Data files and printing forms
4.2.1 Data files

Data delivered for printing shall be in the colour formats CMYK or three components and should be

exchanged in PDF/X data formats as defined in ISO 15930 (all parts).

The intended printing condition shall be indicated in case of PDF/X data exchange. In case of PDF/X

the mechanisms provided by the specified data format shall be used. In case of other data formats, a

printing condition description, a characterization data set, or an International Colour Consortium (ICC)

output profile shall be communicated.

Data other than CMYK shall be defined by colorimetric description using an ICC profile or other

mechanism. An ICC CMYK output profile should be included. The rendering intent to be used with the

output profile shall be communicated.

If the characterization data or ICC output profile provided conflict with the printing conditions defined

in this part of ISO 12647 one of the methods defined in ISO/TS 10128 shall be used for data adjustment

toward the printing conditions defined in this International Standard.

Checks are recommended to ensure the conformance of the data with the requirements of the

printing standard.
4.2.2 Printing form quality

The resolution of the plate setter shall be set to a minimum frequency of 393cm and should be set to a

minimum frequency of 500cm .
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The deviation of similar tone values of the data file in different areas of the printing form shall not

exceed ± 1,5 tone value %.
4.2.3 Screen frequency (periodic screens)
−1 −1

For all half-tone elements, the screen frequency should be between 40 cm and 54 cm . Within the same

print product the screen ruling shall be the same for colour and black-and-white printing. If other screen

rulings are used the tone value increase shall be adjusted such that it agrees with Table 7 and Figure 3.

NOTE 1 Older Raster Image Processor (RIP) software might not be able to produce the requested screen angle

at the requested screen ruling exactly. This is why with computer-generated screens, the parameters screen

ruling and screen angle can be varied slightly.

NOTE 2 Screen frequencies are often required or given in lpi (lines per inch). To convert between lines per

centimetre and lines per inch a conversion factor of 2,54 should be used. For example the requirement of 40 and

54 given in lpi will read as follows (rounded to commonly used integral numbers): for all half-tone elements, the

screen frequency should be between 100 lpi and 140 lpi.
4.2.4 Screen dot size (non-periodic screens)

The screen dot size for non-periodic screens should be 40 µm ± 10 µm, depending on substrate

requirements.
4.2.5 Screen angle (periodic screens)

For half-tone dots without a principal axis, the nominal difference between the screen angles for cyan,

magenta and black should be 30°, with the screen angle of yellow separated at 15° from another colour.

The screen angle of the dominant colour should be 45°. The dominant colour is defined as the one that

contains most of the image information compared to the others. For typical newspaper applications

the dominant colour will be black. Refer to Figure 1 for an example of a screen angle combination for a

screen with a principal axis and with black as the dominant colour.

For half-tone dots with a principal axis (elliptical half-tone dot shape), the nominal difference between

screen angles for cyan, magenta and black should be 60°, with the screen angle of yellow at 0° and 15° off

from the next screen angle. The screen angle of the dominant colour should be 45° or 135°.

Figure 1 — Example of a screen angle combination for a screen with a principal axis and with

black as the dominant colour

NOTE The dominant colour is defined as that which contains most of the image information compared to the

others. For typical newspaper colour separations with GCR the dominant colour will be black.

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4.2.6 Dot shape and its relationship to tone value (periodic screens)

For periodic screens, elliptical half-tone dot shapes should be used. For half-tone dots with a principal

axis, the first link-up should occur no lower than at 40 % tone value (data) and the second link-up no

higher than at 60 % tone value (data).
4.2.7 Tone value sum

Unless otherwise specified, the tone value sum should not exceed 220 % and shall not exceed 240 %.

Where the maximum tone value sum approaches this limit, the tone value of black should be at least 90 %.

NOTE Any colour that is reproduced using all three chromatic process inks can be thought of as having a

neutral component. This is defined by the lowest tone value and its grey balance equivalents of the other two

inks. It is possible to replace all or some of the neutral component by black ink. Under colour removal (UCR) limits

the tone value sum by replacing chromatic colour ink with black ink in the neutral shadows. Grey component

replacement (GCR) replaces chromatic colour ink with black ink in the entire colour space. GCR is recommended

for newspaper colour separations because it reduces colour variations caused by poor ink trapping, back transfer,

set-off during the print run, and eases registration.
4.2.8 Grey reproduction and grey balance

The grey balance in printing can effectively be used for print quality control in newspaper print

production. Since typical newsprint does not have a neutral but a yellowish colour, the following

calculation method of grey balance in printing should be applied for coldset printing.

The tone values of cyan, magenta and yellow leading to a visually neutral grey should be calculated from the

standard printing condition or actual printing condition or the associated profiles by the following formula

describing the grey reproduction La*, *,b* w it h respec t to a g iven paper colour La*, *,b*

() ()
paperpaper paper
and CMY-overprint L* for each L* in the range from L* to L* :
cmy paper cmy
 
aa**=× 10−×,*85 LL− */ LL**−
() ()
paper paper papercmy
 
 
bb**=× 10−×,*85 LL− */ LL**−
() ()
paper paper papercmy
 

NOTE 1 A single grey balance condition is usually not sufficient to ensure an achromatic colour for all print

substrates and printing inks that may be used with a given printing process. Therefore the grey balance has to be

determined for each printing condition separately based on a well-defined grey reproduction.

NOTE 2 The grey balance of a given printing process can be used for process calibration and process control as

long as the tolerances for tone value increase and mid-tone spread as defined in Table 7 are not exceeded.

NOTE 3 The multiplying factor of 0,85 represents a visual adaptation of 85 % to the paper white.

NOTE 4 See Annex B for more information on specifying grey balance values.
4.3 Proof or production print
4.3.1 General

A printing condition for coldset offset printing shall be described by a print substrate, a colorant

description, a screening description, an ink set, and a printing sequence. In all printing conditions

described in this part of ISO 12647, the ink set shall be according to ISO 2846-2 and the printing

sequence shall be Cyan – Magenta – Yellow – Black or Black - Cyan – Magenta – Yellow. See specifications

of printing conditions for typical print substrates in Table 1. See Annex E for information on additional

printing conditions.

NOTE 1 Characterization data are based on CMYK which is generally the preferred printing sequence.

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Table 1 — Printing conditions for typical print substrates
Screening description
Print substrate Colorant
Printing
description description Periodic screens Non-periodic screens
condition
(Table 2) (Table 3)
TVI Frequency TVI Spot size
40 cm
Offset Standard newsprint SNP 26 % 26 % 40 µm
to 54 cm

Colorimetric characterization data, as specified in ISO 12642, contain all the data to be specified in

accordance with 4.3.2.1, 4.3.2.3 and 4.3.4.1

NOTE 2 Additional printing conditions based on commonly used print substrates may follow the scheme

described in this and the following clauses.

NOTE 3 Table 1 does not define a paper specification but is intended to give an indication of a reference on

which the target colours can be reached.
4.3.2 Visual characteristics of image components
4.3.2.1 Print substrate colour

The production print substrate shall conform to the L*, a*, b* values and tolerances specified in Table 2.

A digital proof on an electronic display or a digital proof print according to ISO 12647-7 produced

directly from digital data should be used as a visual reference. Press proof printing should be carried

out using a substrate, which matches as closely as possible all of the properties listed in Table 2. For off-

press proofing, the requirements defined in ISO 12647-7 apply. A paper selection in the light of a close

simulation with respect to the aim values defined in Table 2 ensures an easy simulation of the associated

colorant description and therefore the visual appearance.
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Table 2 — CIELAB coordinates, mass-per-area, gloss, and CIE whiteness for typical print substrates

Parameters Print substrate
Characteristic Standard newsprint
Type of surface Uncoated
g/m
Mass-per-area (informative only)
40 to 52 (45)
Brightness C (informative only)
55 to 80
Gloss (informative only)
< 5
Colour
Parameters L* a* b*
White backing (informative only) 85 1 5
Black backing 82 0 3
Tolerance ±4 ±2 ±2
a, b, c
Informative only. A bandwidth of typical values (product properties) applies.

Mass-per-area: values in brackets pertain to the respective colour coordinates (influence of white or black backing).

Measurement is in accordance with ISO 2470-1, ISO brightness.
Measurement is in accordance with ISO 8254-1, TAPPI method.

Measurement is in accordance with ISO 13655-D50 illuminant, 2° observer, 45:0 or 0:45 geometry. Experts of the paper

making industry usually use different measuring conditions. They measure according ISO 2469: C illuminant 2 observer,

d/0° geometry, opaque pad of newsprint backing. Under ISO 2469 conditions and according ISO 5631-1 the following colour

values correspond to the colour coordinates of this table: L* 83,4 / a* -0,3 / b* 5.

NOTE 1 Annex F gives more information on handling differences in paper colour.

NOTE 2 Table 2 does not define a paper specification but is intended to give an indication of a reference on

which the target colours can be reached.
4.3.2.2 Print substrate gloss

The gloss of the print substrate used for press proof printing should be a close simulation to that of the

production print substrate. Matching the gloss of the print substrate is also important for digital proof

printing stipulated in ISO 12647-7.
NOTE Information on gloss values is given in Table 2.
4.3.2.3 Ink set colours (colorant description)

The CIELAB colour coordinates L*, a*, b* of the process colour solids CMYK and the secondary colour

overprints Red (M+Y), Green (C+Y), Blue (C+M) on the OK print shall agree with the aim values specified

in Table 3 within the deviation tolerances specified in Tables 5 and 6. Table 4 specifies the aim values of

ink colours on newsprint measured on white backing and is informative only.

The variability of the process colour solids CMYK during the production run is restricted by the following

condition. For at least 68 % of the prints, the colour differences from the OK print shall not exceed the

appropriate variation tolerances specified in Tables 5 and 6.

At least 68 % of the print production shall follow the conditions expressed in 4.3.2.3, 4.3.4.2 and 4.3.5.

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Table 3 — CIELAB L*, a*, b* aim values of ink colours on newsprint black backing
measurements (normative)
Colour L* a* b*
Unit 1 1 1
Cyan 57 −23 −27
Magenta 54 44 −1
Yellow 78 −3 58
Black 36 1 4
Cyan + yellow 53 −34 17
Cyan + magenta 41 7 −22
Magenta + yellow 52 41 25
Cyan + magenta + yellow 40 0 1
Four-colour black; (K = 100 %, C = 52 %, M = 44 %,
34 1 2
Y = 44 %)

These values are aim values for the (dry) print product delivered to the customer. Measurements should be made using M1,

in accordance with ISO 13655-D50 illuminant, 2° observer, 45:0 or 0:45 geometry. Values for four-colour black are based on

colour sequence CMYK in printing.

Table 4 — CIELAB L*, a*, b* aim values of ink colours on newsprint white backing measurements

(informative only)
Colour L* a* b*
Unit 1 1 1
Cyan 59 −24 −27
Magenta 56 48 1
Yellow 80 −1 62
Black 37 1 4
Cyan + yellow 55 −34 17
Cyan + magenta 42 7 −23
Magenta + yellow 54 45 26
Cyan + magenta + yellow 40 0 0
Four-colour black; (K = 100 %, C = 52 %, M = 44 %,
35 0 2
Y = 44 %)

These values are aim values for the (dry) print product delivered to the customer. Measurements should be made using M1,

in accordance with ISO 13655-D50 illuminant, 2° observer, 45:0 or 0:45 geometry. Values for four-colour black are based on

colour sequence CMYK in printing.

NOTE 1 The secondary colours red, green, blue can vary depending on conditions that include the mechanics

of the press, the surface characteristics of the print substrate and the rheological and transparency properties of

the inks. Thus, conformance of the primaries C, M, Y to specifications is not sufficient for the conformance of the

secondaries to the values given in Tables 3 and 4.

NOTE 2 The values in Table 3 and Table 4 relate to printing with ink sets in accordance with ISO 2846-2; they

were derived from press runs in the field.

NOTE 3 The distribution of CIELAB values is not Gaussian but skewed. For reasons of consistency, the variation

tolerance is defined here as the upper limit for 68 % of the production copies. This is in analogy with a Gaussian

distribution where 68 % are within plus or minus one standard deviation from the mean.

NOTE 4 As a secondary reference, reflection densities for the process colours as measured with two different

[3] [6]

densitometer types are provided in Annex A. In and a reference to a complete list of X, Y, Z and CIELAB values

of a complete ISO 12642 target is given.
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Figure 2 shows the CIELAB L*, a*, b* black backing a
...

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