Graphic technology - Process control for the production of half-tone colour separations, proofs and production prints - Part 6: Flexographic printing

This document specifies the requirements for the exchange of data and information necessary for the definition of the aims for four-colour flexographic printing of packaging and publication materials, including newsprint. It is based on the use of colour characterization data to define the colourimetric printing aims and includes appropriate assignment of responsibility for and recommended tolerances on critical parameters of the flexographic printing process.
This document is directly applicable to:
— publication flexographic printing including magazines, catalogues and commercial materials and packaging flexographic printing including labels, boxes, and flexible packages;
— half-tone and continuous tone proofing processes that predict the colourimetric results of flexographic printing.
Guidance is also provided concerning the definition of spot colours used in flexographic printing.

Technologie graphique - Contrôle des processus de confection de sélections couleurs tramées, d'épreuves et de tirages - Partie 6: Processus flexographique

Grafična tehnologija - Vodenje procesa izdelave rastriranih barvnih izvlečkov, preskusnih in proizvodnih odtisov - 6. del: Fleksotisk

General Information

Status
Published
Publication Date
09-Jun-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
09-Nov-2020
Due Date
14-Jan-2021
Completion Date
10-Jun-2021

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SLOVENSKI STANDARD
SIST ISO 12647-6:2021
01-julij-2021
Nadomešča:
SIST ISO 12647-6:2014
Grafična tehnologija - Vodenje procesa izdelave rastriranih barvnih izvlečkov,
preskusnih in proizvodnih odtisov - 6. del: Fleksotisk

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

proofs and production prints - Part 6: Flexographic printing

Technologie graphique - Contrôle des processus de confection de sélections couleurs

tramées, d'épreuves et de tirages - Partie 6: Processus flexographique
Ta slovenski standard je istoveten z: ISO 12647-6:2020
ICS:
37.100.01 Grafična tehnologija na Graphic technology in
splošno general
SIST ISO 12647-6:2021 en

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

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SIST ISO 12647-6:2021
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SIST ISO 12647-6:2021
INTERNATIONAL ISO
STANDARD 12647-6
Third edition
2020-09
Graphic technology — Process control
for the production of half-tone colour
separations, proofs and production
prints —
Part 6:
Flexographic printing
Technologie graphique — Contrôle des processus de confection de
sélections couleurs tramées, d'épreuves et de tirages —
Partie 6: Processus flexographique
Reference number
ISO 12647-6:2020(E)
ISO 2020
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 12647-6:2021
ISO 12647-6:2020(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 Material input requirements ....................................................................................................................................................... 3

4.2.1 General...................................................................................................................................................................................... 3

4.2.2 Distortion correction ........................................................................................................................................... ......... 3

4.2.3 Proof requirements ....................................................................................................................................................... 3

4.2.4 Digital data files ................................................................................................................................................................ 3

4.2.5 Film/printing forme requirements .................................................................................................................. 4

4.3 Printing aims............................................................................................................................................................................................. 5

4.3.1 General...................................................................................................................................................................................... 5

4.3.2 Halftoning parameters ................................................................................................................................................ 6

4.3.3 Print substrates ................................................................................................................................................................. 6

4.3.4 Ink set colours .................................................................................................................................................................... 7

4.3.5 Reproducibility of ink colour set ........................................................................................................................ 8

4.3.6 Ink set gloss .......................................................................................................................................................................... 8

4.3.7 Tolerance for image positioning ......................................................................................................................... 9

4.3.8 Tone value increase (TVI) ........................................................................................................................................ 9

4.3.9 Reproducibility of printing ..................................................................................................................................... 9

5 Communication ...................................................................................................................................................................................................... 9

Annex A (normative) Communication of spot colour data .........................................................................................................11

Annex B (informative) Information exchange .........................................................................................................................................12

Annex C (informative) Determination of quality parameters of half-tone dots on a colour

separation film ....................................................................................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................16

© ISO 2020 – All rights reserved iii
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SIST ISO 12647-6:2021
ISO 12647-6:2020(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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 130, Graphic technology.

This third edition cancels and replaces the second edition (ISO 12647-6:2012), which has been

technically revised. It also incorporates the Amendment ISO 12647-6:2012/Amd 1:2015.

The main changes compared to the previous edition are as follows:

— the intent of the document has been changed from a process control definition to a specification of

the way to exchange the information necessary to define the printing characteristics of the desired

product. To do this, it has built on colour management technology and the exchange of colour

characterization data.
A list of all parts in the ISO 12647 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)
Introduction

Historically, the ISO 12647 series of International Standards established the process control

parameters and their aim values and tolerances for the most important professional printing processes

of the graphic arts industry. The initial concept was that the groundwork for the series was laid down

in ISO 12647-1. This document differs from that concept because flexographic printing has changed

significantly since the ISO 12647 series was initially conceived.

This current edition differs from the earlier edition by not defining specific printing condition aims, but

instead requiring that a specific reference printing condition (characterization data set) be specified.

Flexographic printing differs from other printing procedures by using a variety of printing machine

architectures, ink sequence, ink types, anilox rollers, substrate types, etc. Each of these involve

different printing condition and process control aims. This document requires that the colour of the

printed product match a characterization data set or a printing condition agreed upon by the provider

and the receiver. It specifies minimum requirements and tolerances to be communicated and produced.

The purpose of a proof is to simulate the visual characteristics of the finished printed product as closely

as possible, which often becomes a contractual agreement between the provider and the receiver.

ISO 12647-7 defines a process where colour characterization data are used to produce a contract proof.

Defined output intent should be a smooth data set, it is recommended to use an industry accepted

Reference characterization data set. The use of a data set from an old flexographic press results in a

lumpy characterization data, and consequently problematic transforms. The goal for most packaging is

to render all print to a similar appearance, typically the same aim reference characterization data set is

used for flexographic, offset, gravure, and digital printing.

This market also uses colour proofing on electronic displays. The International Standards for colour

proofing on electronic displays are ISO 14861 and ISO 12646.

Spot colour management is defined in this document to utilize spectral data in an XML schema defined

by ISO 17972-4. ISO 17972-4 includes exchange specifications for spot colour characterization data to

facilitate the communication of spot colour data.

There are many cases in this document where the provider and the receiver communicate. Modern

flexography has the capability to align with most other printing aims, however there are some

conditions based on substrate, applications, printing forme technology where aligning to providers

aims cannot be met. Table 5 list all attributes that should be discussed for these exceptions.

© ISO 2020 – All rights reserved v
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SIST ISO 12647-6:2021
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SIST ISO 12647-6:2021
INTERNATIONAL STANDARD ISO 12647-6:2020(E)
Graphic technology — Process control for the production
of half-tone colour separations, proofs and production
prints —
Part 6:
Flexographic printing
1 Scope

This document specifies the requirements for the exchange of data and information necessary for the

definition of the aims for four-colour flexographic printing of packaging and publication materials,

including newsprint. It is based on the use of colour characterization data to define the colourimetric

printing aims and includes appropriate assignment of responsibility for and recommended tolerances

on critical parameters of the flexographic printing process.
This document is directly applicable to:

— publication flexographic printing including magazines, catalogues and commercial materials and

packaging flexographic printing including labels, boxes, and flexible packages;

— half-tone and continuous tone proofing processes that predict the colourimetric results of

flexographic printing.

Guidance is also provided concerning the definition of spot colours used in flexographic printing.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. 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 2813, Paints and varnishes — Determination of gloss value at 20°, 60° and 85°

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

system to match a set of characterization data

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

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

ISO 13468-1, Plastics — Determination of the total luminous transmittance of transparent materials —

Part 1: Single-beam instrument

ISO 13468-2, Plastics — Determination of the total luminous transmittance of transparent materials —

Part 2: Double-beam instrument

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

arts images
ISO 14782, Plastics — Determination of haze for transparent materials

ISO 17223, Plastics — Determination of yellowness index and change in yellowness index

© ISO 2020 – All rights reserved 1
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)

ISO 17972-1, Graphic technology — Colour data exchange format — Part 1: Relationship to CxF3 (CxF/X)

ISO 17972-4, Graphic technology — Colour data exchange format (CxF/X) — Part 4: Spot colour

characterisation data (CxF/X-4)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online Browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
fringe width
size of fuzzy area to the outside of an imaged halftone dot
3.2
printing forme

cylinder or sleeve covered with a relief type rubber or photopolymer plate for application of printing

ink to print substrate

[SOURCE: ISO 2834-2:2007, 3.3, modified — The original term was "printing forme for flexography".]

3.3
provider

organization that prepares the data for printing, distributor of a digital data file, designer, consumer

products company or trade shop
3.4
receiver

organization that receives the file, or to whom a digital data file is delivered,

Note 1 to entry: In the context of this document, usually a prepress company, printer or converter.

3.5
replacement colour
spot colour (3.7) used, with altered separations, in place of a process colour
3.6
screen ruling

number of image elements, such as dots or lines, per unit of length in the direction which produces the

highest value
3.7
spot colour

non-process colour that is used in addition to, or in place of, a process colour and is normally applied

with a single impression

Note 1 to entry: When associated with a corporate product identity, a spot colour is also known as brand colour.

4 Requirements
4.1 General

In all cases, digital data files, colour separation film sets or printing formes delivered for printing shall

be accompanied by a contract proof or a soft proof unless there is an agreement between all parties

concerned that soft proof may be used or that no proof is required. If delivered, the contract proof shall

2 © ISO 2020 – All rights reserved
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)

simulate the intended printing condition including finishing and shall conform to ISO 12647-7, using a

defined control bar per ISO 12647-7. This fact shall be verifiable by measuring a well-specified control

strip or a similar control target suitable for measured verification that is printed on the proof print

along with the subject.

NOTE Where intermediate proofs are needed to simulate the printed product without finishing applied,

these are typically prepared by the printer.
4.2 Material input requirements
4.2.1 General

Input for flexographic printing may be either film, digital data or printing formes. It should be noted

that the use of film or printing formes as the interchange format between the provider and the receiver

should include additional details (such as image distortion) not covered in detail in this document.

4.2.2 Distortion correction

There is currently no agreement as to a single formula for image distortion. Therefore, the computation

to be used shall be agreed upon between the provider and the receiver.
4.2.3 Proof requirements

All input for flexographic printing (film, digital data or printing formes) shall be accompanied by a proof

prepared in accordance with ISO 12647-7 unless there is prior agreement that a proof is not required,

or that an agreed upon soft proof will be used.
4.2.4 Digital data files

Data delivered for printing shall be in the colour formats of CMYK, CMYK plus spot colours, or CMYK

with spot colour as replacement for CMYK colours. The actual data delivered may be either final

format data or three-component colour data sets with associated colour profiles to allow the data to be

converted to the final data format. The intended printing condition shall be defined with sufficient data

to allow at least one of the three methods described in ISO/TS 10128 to be applied for establishing the

printing aims. Where the intended printing condition is included in the registry of characterizations

maintained by the ICC, and the digital data are CMYK, the name used in the ICC registry may be used for

identification in lieu of including an ICC output profile. If the intended printing condition is not included

in said registry, an ICC output profile shall be included.

If the process colorants are other than CMYK, the data shall be defined colourimetrically using an

ICC destination profile that shall be referenced, along with spectral data defined in ISO 17972-4; the

rendering intent to be used with the output profile shall be communicated.

The colour gamut of the aim reference printing conditions should be aligned to the intended press gamut.

Where the aim data set cannot be achieved by the printing system, it is the receiver’s responsibility to

communicate and agree on resolution with the provider of the file.

The file format used for data exchange shall be PDF/X and should be in accordance with ISO 15930-7.

The ISO 15930 series provides many versions of PDF, for global continuity PDF/X-4 for blind transfer

delivers files containing fonts, images, and colour requirements and should be used.

Spot colours measurement data (for example Brand colours) shall be communicated between the

provider and the receiver and should be communicated as CxF/X-4, CxF X-4a or CxF X-4b as defined

ISO 17972-4 or ISO 17972-1 with spectral reflectance data. It may be embedded in the PDF/X document

output intents as mixing hints as specified in ISO 32000-2, by prior agreement between the provider

and the receiver.
© ISO 2020 – All rights reserved 3
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)

The ICC profile should include tables that provide smooth transforms. One method to inspect the

smoothness of a profile is to use a test image with colour vignettes for primary and secondary colours,

as well as images with smooth contours.

NOTE Communication of spot colours as part of digital data exchange is defined by a number of International

Standards. See Annex A.

The ISO 15930 series defines many versions of PDF which may be used by prior agreement between the

document designer and printer.
4.2.5 Film/printing forme requirements
4.2.5.1 Colour separations

In order to permit the reproduction of at least 100 tone value steps, the resolution of the image setter or

printing forme setter should be set to the appropriate resolution for the screen ruling required for the

printing application.
The fringe width shall not be greater than one fortieth of the screen ruling.
4.2.5.2 Printing forme digital (laser ablative mask or thermal imaging layer)

In the case of digital plate making processes based on laser ablative mask, the mask material and plate

sensitivity varies substantially from manufacturer to manufacturer. It is therefore not possible to

provide a recommendation that would apply to all plate types. Users shall follow the recommendations

for ablation and plate exposure specified by the manufacturer.
4.2.5.3 Film

When film is provided, the matte negative colour separation film shall have a core density of 4,0 or

above. The transmission density in the centre of a clear half-tone dot shall not be higher than 0,1 above

the corresponding value of a large clear area. The transmission density of the clear film shall not be

higher than 0,15. Both measurements shall be made with transmission densitometer whose spectral

products conform to printing density as defined in ISO 5-3.

The clear film density requirement is based on the understanding that the density range of the clear

areas of all films that are to be exposed onto the same plate need to be within a printing density range

of 0,10. Experience has proved that 0,05 represents the lowest commonly found value for ISO 5 Type 1

printing density. For half-tone films with clear film densities above this range, agreements between

the supplier of colour separations and the recipient are required. Contacting or duplicating may also be

used to bring half-tone films with dissimilar clear film densities into agreement.

As a practical guide, a core density of 4,0 above the clear film density should be achieved if the density

of large solid areas is more than 4,0 above the clear film density.

NOTE 1 Other than for the clear film density requirement, the colour separation film quality can be evaluated

according to Annex C.

NOTE 2 This tolerance includes image or printing forme setter repeatability and material stability.

4.2.5.4 Printing forme verification for delivery

Flexographic printing formes, whether prepared by the provider or the receiver, shall be created with

both an uncompensated and a compensated set of control patches representing the tonal steps of at

least the minimum dot size, and tonal values of 10 %, 30 %, 50 %, 70 %, and a solid.

For the uncompensated set of patches, the tone values measured on the printing forme shall be within

the tolerances shown in Table 1. This requires that the control patches be exposed independent of the

image content.
4 © ISO 2020 – All rights reserved
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)

For the compensated set of patches, the data in the file associated with these patches shall be the tone

values necessary to produce the indicated value when printed on the substrate. These tone patches,

measured on the printing forme, shall be within tone value tolerance shown in Table 1.

There is no standard method for measuring halftone dot area on the printed forme and there should be

significant differences between measurement devices. A measurement method shall be agreed between

the provider and the receiver.
Table 1 — Tone value tolerances for printing forme delivery
Screen rulings equal to Screen rulings above
Tone value range
−1 −1
or below 48 cm 48 cm
Tone values below or
±1 ±2
equal to 10 %
Tone values above 10 % ±2 ±3

NOTE 1 Because the tone value measured on the printing forme does not necessarily represent the tone value

achieved on the printed sheet, a common calibration process is to expose a digital scale representing the full

tonal scale and use this to calibrate the relationship between tone value measured on the printing forme and

tone value achieved on the printed sheet.

NOTE 2 Because the exposed area of a flexographic printing forme is not necessarily representative of the

tone value is achieved after processing of the printing forme, a common calibration process is to expose a digital

scale representing the full tonal scale and use this to calibrate the relationship between exposed tone value and

tone value achieved on the processed printing forme.

The minimum physical dot printable (min dot) is dependent upon, among other things, the screen ruling,

printing forme technology and anilox roller being used. It requires agreement between the provider

and the receiver of the printing formes.
4.2.5.5 Image size tolerance (film or printing forme)

For a set of colour separation films or printing formes in common environmental equilibrium, the

lengths of the diagonals shall not differ by more than 0,02 %. Modern flexographic plate mounting

systems do not have the capability to measure diagonals. Verification on these devices should be

maintained to be within one row of dots both vertical and horizonal.

NOTE This tolerance includes image or printing forme setter repeatability and material stability.

4.3 Printing aims
4.3.1 General

The flexographic printing process as practiced today is largely based on the use of reference

characterization data and colour management profiles to define the printing aims for the single and

two-colour tone scales and the associated overprint colours. The printer is free to use the appropriate

combination of anilox rollers, printing formes, inks, sleeves and electronic data manipulation (for

example using the principles of ISO/TS 10128) to achieve final printed images that colourimetrically

match the provided characterization data adjusted, if necessary to match the substrate colour as

described in 4.3.3. The primary responsibility of the printer is to provide a consistent reproducible

printing process.

However, there are some parameters that need to be controlled and some general aims that should be

used as guidance for printing. These are addressed in the following clauses.
© ISO 2020 – All rights reserved 5
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SIST ISO 12647-6:2021
ISO 12647-6:2020(E)
4.3.2 Halftoning parameters
4.3.2.1 General

The manufacturers of raster image processors generally recommend specific screen angles and output

resolution for an imaging device in order to provide the smoothest screening. Agreement shall be

reached between the provider and the receiver concerning the particular screening parameters to use.

4.3.2.2 Screen frequency
Agreement shall be reached between the provider and the receiver.
4.3.2.3 Screen angle

Where screen angle is critical, agreement shall be reached between the provider and the receiver.

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

magenta and black shall be 30°, with the screen angle for yellow separ
...

INTERNATIONAL ISO
STANDARD 12647-6
Third edition
2020-09
Graphic technology — Process control
for the production of half-tone colour
separations, proofs and production
prints —
Part 6:
Flexographic printing
Technologie graphique — Contrôle des processus de confection de
sélections couleurs tramées, d'épreuves et de tirages —
Partie 6: Processus flexographique
Reference number
ISO 12647-6:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 12647-6:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 12647-6:2020(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 Material input requirements ....................................................................................................................................................... 3

4.2.1 General...................................................................................................................................................................................... 3

4.2.2 Distortion correction ........................................................................................................................................... ......... 3

4.2.3 Proof requirements ....................................................................................................................................................... 3

4.2.4 Digital data files ................................................................................................................................................................ 3

4.2.5 Film/printing forme requirements .................................................................................................................. 4

4.3 Printing aims............................................................................................................................................................................................. 5

4.3.1 General...................................................................................................................................................................................... 5

4.3.2 Halftoning parameters ................................................................................................................................................ 6

4.3.3 Print substrates ................................................................................................................................................................. 6

4.3.4 Ink set colours .................................................................................................................................................................... 7

4.3.5 Reproducibility of ink colour set ........................................................................................................................ 8

4.3.6 Ink set gloss .......................................................................................................................................................................... 8

4.3.7 Tolerance for image positioning ......................................................................................................................... 9

4.3.8 Tone value increase (TVI) ........................................................................................................................................ 9

4.3.9 Reproducibility of printing ..................................................................................................................................... 9

5 Communication ...................................................................................................................................................................................................... 9

Annex A (normative) Communication of spot colour data .........................................................................................................11

Annex B (informative) Information exchange .........................................................................................................................................12

Annex C (informative) Determination of quality parameters of half-tone dots on a colour

separation film ....................................................................................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................16

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 12647-6:2020(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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 130, Graphic technology.

This third edition cancels and replaces the second edition (ISO 12647-6:2012), which has been

technically revised. It also incorporates the Amendment ISO 12647-6:2012/Amd 1:2015.

The main changes compared to the previous edition are as follows:

— the intent of the document has been changed from a process control definition to a specification of

the way to exchange the information necessary to define the printing characteristics of the desired

product. To do this, it has built on colour management technology and the exchange of colour

characterization data.
A list of all parts in the ISO 12647 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 12647-6:2020(E)
Introduction

Historically, the ISO 12647 series of International Standards established the process control

parameters and their aim values and tolerances for the most important professional printing processes

of the graphic arts industry. The initial concept was that the groundwork for the series was laid down

in ISO 12647-1. This document differs from that concept because flexographic printing has changed

significantly since the ISO 12647 series was initially conceived.

This current edition differs from the earlier edition by not defining specific printing condition aims, but

instead requiring that a specific reference printing condition (characterization data set) be specified.

Flexographic printing differs from other printing procedures by using a variety of printing machine

architectures, ink sequence, ink types, anilox rollers, substrate types, etc. Each of these involve

different printing condition and process control aims. This document requires that the colour of the

printed product match a characterization data set or a printing condition agreed upon by the provider

and the receiver. It specifies minimum requirements and tolerances to be communicated and produced.

The purpose of a proof is to simulate the visual characteristics of the finished printed product as closely

as possible, which often becomes a contractual agreement between the provider and the receiver.

ISO 12647-7 defines a process where colour characterization data are used to produce a contract proof.

Defined output intent should be a smooth data set, it is recommended to use an industry accepted

Reference characterization data set. The use of a data set from an old flexographic press results in a

lumpy characterization data, and consequently problematic transforms. The goal for most packaging is

to render all print to a similar appearance, typically the same aim reference characterization data set is

used for flexographic, offset, gravure, and digital printing.

This market also uses colour proofing on electronic displays. The International Standards for colour

proofing on electronic displays are ISO 14861 and ISO 12646.

Spot colour management is defined in this document to utilize spectral data in an XML schema defined

by ISO 17972-4. ISO 17972-4 includes exchange specifications for spot colour characterization data to

facilitate the communication of spot colour data.

There are many cases in this document where the provider and the receiver communicate. Modern

flexography has the capability to align with most other printing aims, however there are some

conditions based on substrate, applications, printing forme technology where aligning to providers

aims cannot be met. Table 5 list all attributes that should be discussed for these exceptions.

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INTERNATIONAL STANDARD ISO 12647-6:2020(E)
Graphic technology — Process control for the production
of half-tone colour separations, proofs and production
prints —
Part 6:
Flexographic printing
1 Scope

This document specifies the requirements for the exchange of data and information necessary for the

definition of the aims for four-colour flexographic printing of packaging and publication materials,

including newsprint. It is based on the use of colour characterization data to define the colourimetric

printing aims and includes appropriate assignment of responsibility for and recommended tolerances

on critical parameters of the flexographic printing process.
This document is directly applicable to:

— publication flexographic printing including magazines, catalogues and commercial materials and

packaging flexographic printing including labels, boxes, and flexible packages;

— half-tone and continuous tone proofing processes that predict the colourimetric results of

flexographic printing.

Guidance is also provided concerning the definition of spot colours used in flexographic printing.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. 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 2813, Paints and varnishes — Determination of gloss value at 20°, 60° and 85°

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

system to match a set of characterization data

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

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

ISO 13468-1, Plastics — Determination of the total luminous transmittance of transparent materials —

Part 1: Single-beam instrument

ISO 13468-2, Plastics — Determination of the total luminous transmittance of transparent materials —

Part 2: Double-beam instrument

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

arts images
ISO 14782, Plastics — Determination of haze for transparent materials

ISO 17223, Plastics — Determination of yellowness index and change in yellowness index

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ISO 12647-6:2020(E)

ISO 17972-1, Graphic technology — Colour data exchange format — Part 1: Relationship to CxF3 (CxF/X)

ISO 17972-4, Graphic technology — Colour data exchange format (CxF/X) — Part 4: Spot colour

characterisation data (CxF/X-4)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online Browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
fringe width
size of fuzzy area to the outside of an imaged halftone dot
3.2
printing forme

cylinder or sleeve covered with a relief type rubber or photopolymer plate for application of printing

ink to print substrate

[SOURCE: ISO 2834-2:2007, 3.3, modified — The original term was "printing forme for flexography".]

3.3
provider

organization that prepares the data for printing, distributor of a digital data file, designer, consumer

products company or trade shop
3.4
receiver

organization that receives the file, or to whom a digital data file is delivered,

Note 1 to entry: In the context of this document, usually a prepress company, printer or converter.

3.5
replacement colour
spot colour (3.7) used, with altered separations, in place of a process colour
3.6
screen ruling

number of image elements, such as dots or lines, per unit of length in the direction which produces the

highest value
3.7
spot colour

non-process colour that is used in addition to, or in place of, a process colour and is normally applied

with a single impression

Note 1 to entry: When associated with a corporate product identity, a spot colour is also known as brand colour.

4 Requirements
4.1 General

In all cases, digital data files, colour separation film sets or printing formes delivered for printing shall

be accompanied by a contract proof or a soft proof unless there is an agreement between all parties

concerned that soft proof may be used or that no proof is required. If delivered, the contract proof shall

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ISO 12647-6:2020(E)

simulate the intended printing condition including finishing and shall conform to ISO 12647-7, using a

defined control bar per ISO 12647-7. This fact shall be verifiable by measuring a well-specified control

strip or a similar control target suitable for measured verification that is printed on the proof print

along with the subject.

NOTE Where intermediate proofs are needed to simulate the printed product without finishing applied,

these are typically prepared by the printer.
4.2 Material input requirements
4.2.1 General

Input for flexographic printing may be either film, digital data or printing formes. It should be noted

that the use of film or printing formes as the interchange format between the provider and the receiver

should include additional details (such as image distortion) not covered in detail in this document.

4.2.2 Distortion correction

There is currently no agreement as to a single formula for image distortion. Therefore, the computation

to be used shall be agreed upon between the provider and the receiver.
4.2.3 Proof requirements

All input for flexographic printing (film, digital data or printing formes) shall be accompanied by a proof

prepared in accordance with ISO 12647-7 unless there is prior agreement that a proof is not required,

or that an agreed upon soft proof will be used.
4.2.4 Digital data files

Data delivered for printing shall be in the colour formats of CMYK, CMYK plus spot colours, or CMYK

with spot colour as replacement for CMYK colours. The actual data delivered may be either final

format data or three-component colour data sets with associated colour profiles to allow the data to be

converted to the final data format. The intended printing condition shall be defined with sufficient data

to allow at least one of the three methods described in ISO/TS 10128 to be applied for establishing the

printing aims. Where the intended printing condition is included in the registry of characterizations

maintained by the ICC, and the digital data are CMYK, the name used in the ICC registry may be used for

identification in lieu of including an ICC output profile. If the intended printing condition is not included

in said registry, an ICC output profile shall be included.

If the process colorants are other than CMYK, the data shall be defined colourimetrically using an

ICC destination profile that shall be referenced, along with spectral data defined in ISO 17972-4; the

rendering intent to be used with the output profile shall be communicated.

The colour gamut of the aim reference printing conditions should be aligned to the intended press gamut.

Where the aim data set cannot be achieved by the printing system, it is the receiver’s responsibility to

communicate and agree on resolution with the provider of the file.

The file format used for data exchange shall be PDF/X and should be in accordance with ISO 15930-7.

The ISO 15930 series provides many versions of PDF, for global continuity PDF/X-4 for blind transfer

delivers files containing fonts, images, and colour requirements and should be used.

Spot colours measurement data (for example Brand colours) shall be communicated between the

provider and the receiver and should be communicated as CxF/X-4, CxF X-4a or CxF X-4b as defined

ISO 17972-4 or ISO 17972-1 with spectral reflectance data. It may be embedded in the PDF/X document

output intents as mixing hints as specified in ISO 32000-2, by prior agreement between the provider

and the receiver.
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ISO 12647-6:2020(E)

The ICC profile should include tables that provide smooth transforms. One method to inspect the

smoothness of a profile is to use a test image with colour vignettes for primary and secondary colours,

as well as images with smooth contours.

NOTE Communication of spot colours as part of digital data exchange is defined by a number of International

Standards. See Annex A.

The ISO 15930 series defines many versions of PDF which may be used by prior agreement between the

document designer and printer.
4.2.5 Film/printing forme requirements
4.2.5.1 Colour separations

In order to permit the reproduction of at least 100 tone value steps, the resolution of the image setter or

printing forme setter should be set to the appropriate resolution for the screen ruling required for the

printing application.
The fringe width shall not be greater than one fortieth of the screen ruling.
4.2.5.2 Printing forme digital (laser ablative mask or thermal imaging layer)

In the case of digital plate making processes based on laser ablative mask, the mask material and plate

sensitivity varies substantially from manufacturer to manufacturer. It is therefore not possible to

provide a recommendation that would apply to all plate types. Users shall follow the recommendations

for ablation and plate exposure specified by the manufacturer.
4.2.5.3 Film

When film is provided, the matte negative colour separation film shall have a core density of 4,0 or

above. The transmission density in the centre of a clear half-tone dot shall not be higher than 0,1 above

the corresponding value of a large clear area. The transmission density of the clear film shall not be

higher than 0,15. Both measurements shall be made with transmission densitometer whose spectral

products conform to printing density as defined in ISO 5-3.

The clear film density requirement is based on the understanding that the density range of the clear

areas of all films that are to be exposed onto the same plate need to be within a printing density range

of 0,10. Experience has proved that 0,05 represents the lowest commonly found value for ISO 5 Type 1

printing density. For half-tone films with clear film densities above this range, agreements between

the supplier of colour separations and the recipient are required. Contacting or duplicating may also be

used to bring half-tone films with dissimilar clear film densities into agreement.

As a practical guide, a core density of 4,0 above the clear film density should be achieved if the density

of large solid areas is more than 4,0 above the clear film density.

NOTE 1 Other than for the clear film density requirement, the colour separation film quality can be evaluated

according to Annex C.

NOTE 2 This tolerance includes image or printing forme setter repeatability and material stability.

4.2.5.4 Printing forme verification for delivery

Flexographic printing formes, whether prepared by the provider or the receiver, shall be created with

both an uncompensated and a compensated set of control patches representing the tonal steps of at

least the minimum dot size, and tonal values of 10 %, 30 %, 50 %, 70 %, and a solid.

For the uncompensated set of patches, the tone values measured on the printing forme shall be within

the tolerances shown in Table 1. This requires that the control patches be exposed independent of the

image content.
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For the compensated set of patches, the data in the file associated with these patches shall be the tone

values necessary to produce the indicated value when printed on the substrate. These tone patches,

measured on the printing forme, shall be within tone value tolerance shown in Table 1.

There is no standard method for measuring halftone dot area on the printed forme and there should be

significant differences between measurement devices. A measurement method shall be agreed between

the provider and the receiver.
Table 1 — Tone value tolerances for printing forme delivery
Screen rulings equal to Screen rulings above
Tone value range
−1 −1
or below 48 cm 48 cm
Tone values below or
±1 ±2
equal to 10 %
Tone values above 10 % ±2 ±3

NOTE 1 Because the tone value measured on the printing forme does not necessarily represent the tone value

achieved on the printed sheet, a common calibration process is to expose a digital scale representing the full

tonal scale and use this to calibrate the relationship between tone value measured on the printing forme and

tone value achieved on the printed sheet.

NOTE 2 Because the exposed area of a flexographic printing forme is not necessarily representative of the

tone value is achieved after processing of the printing forme, a common calibration process is to expose a digital

scale representing the full tonal scale and use this to calibrate the relationship between exposed tone value and

tone value achieved on the processed printing forme.

The minimum physical dot printable (min dot) is dependent upon, among other things, the screen ruling,

printing forme technology and anilox roller being used. It requires agreement between the provider

and the receiver of the printing formes.
4.2.5.5 Image size tolerance (film or printing forme)

For a set of colour separation films or printing formes in common environmental equilibrium, the

lengths of the diagonals shall not differ by more than 0,02 %. Modern flexographic plate mounting

systems do not have the capability to measure diagonals. Verification on these devices should be

maintained to be within one row of dots both vertical and horizonal.

NOTE This tolerance includes image or printing forme setter repeatability and material stability.

4.3 Printing aims
4.3.1 General

The flexographic printing process as practiced today is largely based on the use of reference

characterization data and colour management profiles to define the printing aims for the single and

two-colour tone scales and the associated overprint colours. The printer is free to use the appropriate

combination of anilox rollers, printing formes, inks, sleeves and electronic data manipulation (for

example using the principles of ISO/TS 10128) to achieve final printed images that colourimetrically

match the provided characterization data adjusted, if necessary to match the substrate colour as

described in 4.3.3. The primary responsibility of the printer is to provide a consistent reproducible

printing process.

However, there are some parameters that need to be controlled and some general aims that should be

used as guidance for printing. These are addressed in the following clauses.
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4.3.2 Halftoning parameters
4.3.2.1 General

The manufacturers of raster image processors generally recommend specific screen angles and output

resolution for an imaging device in order to provide the smoothest screening. Agreement shall be

reached between the provider and the receiver concerning the particular screening parameters to use.

4.3.2.2 Screen frequency
Agreement shall be reached between the provider and the receiver.
4.3.2.3 Screen angle

Where screen angle is critical, agreement shall be reached between the provider and the receiver.

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

magenta and black shall be 30°, with the screen angle for yellow separated by 15° from another colour.

No colour should align with engraving pattern on the anilox roller.

Typically, ceramic anilox rollers are engraved at 60° and mechanically engraved rollers are engraved

at 45°. The provider needs to communicate with the receiver in order to avoid conflict with the actual

anilox engraving angle.
4.3.2.4 Dot shape and its relationship to tone value

Round dots are recommended since they provide the best process consistency for a given resolution,

and the best available resolution for process consistency. When delivering printing formes, agreement

shall be reached between the provider and the receiver.
4.3.2.5 Tone value sum of the printing forme

The tone value sum should be equal to or less than 320 % for four colours unless there is prior agreement

between the provider and the receiver.

NOTE The tone value sum requirement is intended for general guidance as a maximal limit only. The actual

limitations on tone value sum are a function of, among other things, the type of ink used (solvent, water-based,

UV cured, etc.), the substrate, dryer configurations, and inline converting processes. Press trials provide the

appropriate tone value sum for a particular process.
4.3.2.6 Tone value reproduction limits
...

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