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

ISO 12647-3:2005 specifies a number of process parameters and their values to be applied when preparing colour separations for newspaper single or four-colour printing and proofing. The parameters and values are chosen in consideration of the complete process, covering the process stages: colour separation, film setting, making of the printing forme, proof production and production printing. ISO 12647-3:2005 is applicable: to coldset offset proof and production printing and off-press proof printing processes on newsprint that use colour separation films rather than digital data; by analogy to press printing from printing surfaces produced by direct imaging methods and the corresponding proof printing processes.

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 ter preskusnih in proizvodnih odtisov – 3. del: Procesi v časopisnem ofsetnem tisku na rotacijah s hladnim sušenjem

General Information

Status
Withdrawn
Publication Date
27-Sep-2005
Withdrawal Date
27-Sep-2005
Current Stage
9599 - Withdrawal of International Standard
Start Date
12-Dec-2013
Completion Date
12-Dec-2013

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INTERNATIONAL ISO
STANDARD 12647-3
Second edition
2005-10-01
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 12647-3:2005(E)
ISO 2005
---------------------- Page: 1 ----------------------
ISO 12647-3:2005(E)
PDF disclaimer

This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but

shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In

downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat

accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.

Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation

parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In

the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

© ISO 2005

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

electronic or mechanical, including photocopying and microfilm, without permission in writing 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 2005 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 12647-3:2005(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 file, colour separation films and printing formes ..................................................................... 2

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

4.4 Additional requirements for single-colour reproduction and printing.......................................... 10

5 Test method: tone value and tone value increase of a print.......................................................... 10

Annex A (informative) Tolerances for the secondary colour solids ........................................................... 11

Annex B (informative) Densities of ink set colours ...................................................................................... 12

Annex C (informative) Characterization data for 26 % and 30 % tone value increase .............................. 13

Annex D (informative) Grey balance............................................................................................................... 14

Bibliography ..................................................................................................................................................... 15

© ISO 2005 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 12647-3:2005(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 12647-3 was prepared by Technical Committee ISO/TC 130, Graphic technology.

This second edition cancels and replaces the first edition (ISO 12467-3:1998) which has been technically

revised, in particular the tone value increase values specified, as borne out by the print characteristic curves

of Figure 3. Parameters of all process steps have to be adjusted to achieve these curves; they apply

irrespective of whether a positive or a negative acting plate making process is used. The reference to

letterpress has been removed completely. Some solid colour CIELAB values have been changed slightly in

response to demands from the field.

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

the production of half-tone colour separations, proofs 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
iv © ISO 2005 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 12647-3:2005(E)
Introduction

When producing a half-tone colour reproduction it is important that the colour separator, proofer 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") and subsequent production of off-press or on-press

proof prints from these separations whose purpose is to simulate the visual characteristics of the finished print

product as closely as possible.
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 proof or production

print produced by coldset offset lithography on newsprint, or half-tone proof designed to simulate this, from a

set of half-tone separation films.

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 or proof produced

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

recommended for specification.

Since non-periodic screening and direct-to-plate techniques are common practice within newspaper printing,

information on some of the pertinent parameters has been included.
© ISO 2005 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 12647-3:2005(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

preparing colour separations for newspaper single or four-colour printing and proofing. The parameters and

values are chosen in consideration of the complete process, covering the process stages: “colour separation”,

“film setting”, “making of the printing forme”, “proof production” and “production printing”.

This part of ISO 12647 is applicable:

⎯ to coldset offset proof and production printing and off-press proof printing processes on newsprint that

use colour separation films rather than digital data;

⎯ by analogy to press printing from printing surfaces produced by direct imaging methods and the

corresponding proof printing processes.
⎯ It is not applicable:

⎯ to line screens and non-periodic screens although certain parameters given can be applied by analogy. In

particular, the tone value increases specified, apply directly because they refer to control patches that

contain periodic screen half-tones;

⎯ to flexo and letterpress production printing although a number of parameters can be applied by analogy.

2 Normative references

The following referenced documents are indispensable for the application 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 — Density measurements — Part 3: Spectral conditions

ISO 8254-1, Paper and board — Measurement of specular gloss — Part 1: 75 degree gloss with a converging

beam, TAPPI method

ISO 12647-1:2004, Graphic technology — Process control for the production of half-tone colour separations,

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

ISO 15930-4, Graphic technology — Prepress digital data exchange using PDF — Part 4: Complete exchange

of CMYK and spot colour printing data using PDF 1.4 (PDF/X-1a)

ISO 15930-6, Graphic technology — Prepress digital data exchange using PDF — Part 6: Complete exchange

of printing data suitable for colour-managed workflows using PDF 1.4 (PDF/X-3)
© ISO 2005 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 12647-3:2005(E)
3 Terms and definitions

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

3.1
coldset offset lithography

method of offset lithographic printing where the inks set ("dry") primarily by absorption into the print substrate

4 Requirements
4.1 General

The following subclauses are arranged according to the order set out in ISO 12647-1. They also depend on it

for the definition of the parameters and test methods.

If data files or colour separation film sets are supplied for printing they should be accompanied by a proof print

that simulates the intended production printing condition to a sufficient degree. This fact shall be verifiable by

measuring a well-known control strip or a similar control device that is printed on the proof print along with the

subject.
4.2 Data file, colour separation films and printing formes
4.2.1 General

Electronic data should be delivered as PDF/X-1 or PDF/X-3 data files as defined in ISO 15930-4 or

ISO 15930-6. Where film is supplied, the intended receiver of the film shall specify the tone value curve for

which the film shall be prepared.
4.2.2 Film or printing forme quality

The tone values for film and printing formes shall be adjusted such that, for all primary colours, the tone value

increase from data to paper conforms to one of the two curves specified in 4.3.4.1. Within an ink set, the

printed characteristics of all the primary printing ink colours shall conform to the same tone value curve.

NOTE 1 Data sender and receiver need to agree on which of the two curves specified in Table 5 and shown in Figure 3

will be used. The choice of the appropriate curve for common use is generally made by national or international trade

associations.

NOTE 2 Methods for tone value adjustments include setting of the RIP look-up table, choosing a suitable blanket type,

suitable setting of the plate to blanket pressure and adjustment of the ink rheology.

EXAMPLE 1 Conventional plate making with negative film produces a tone value increase of 33 % in the mid tone. In

order to achieve 26 %, the RIP look-up table was adjusted by − 4 % and the choice of a different ink generated a 3 %

lower tone value increase. These two adjustments lowered the tone value increase to 26 %. If 30 % is to be achieved, less

adjustments are necessary to reach the correct tone value increase.

EXAMPLE 2 With a given CTP system the tone value increase was found to be 22 %. An increased blanket to plate

pressure yielded + 2 %, the remaining + 2 % were introduced at the RIP look-up table; 26 % tone value increase was

achieved.

The resolution of the film or plate setter should be set to 500 cm and shall not be set to a lower value than

472 cm in order to assure a sufficient number of generated tone value steps.

The deviation of tone values over the complete printing forme shall not exceed ± 2 %. The deviation range of

the measuring device (densitometer or camera-based device) shall be added to this value.

2 © ISO 2005 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 12647-3:2005(E)

Unless otherwise specified, the core density of a colour separation film shall be at least 2,5 above the

transmission density of the clear film (film base plus fog). The transmission density in the centre of a clear

half-tone dot shall not be more 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.
The fringe width of a colour separation film shall not be greater than 6 µm.

The colour separation film quality should be evaluated according to Annex B of ISO 12647-1:2004.

Measurements shall be made with a (UV) transmission densitometer whose spectral products conform to

ISO type 1 printing density as defined in ISO 5-3; for the evaluation of core properties, type 2 printing density

may be used.

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 on to an offset plate, for consistent work, should not exceed 0,10.

NOTE 3 As a practical guide, a core density of 2,5 above the clear film density will normally be achieved if the density

of large solid areas is more than 3,5 above the clear film density.

NOTE 4 With non-periodic screens, a fringe width of not more than 4 µm is reported to give reliable results.

4.2.3 Screen frequency

For four-colour work, the screen frequency should be (40 ± 2) cm . Within the same copy of a newspaper,

the screen ruling shall be the same for colour and black-and-white printing. If, as an exception, other screen

rulings are used, the tone value increase shall be adjusted such that it agrees with Table 5 and Figure 3.

NOTE 1 With computer-generated screening, the parameters screen ruling and screen angle can be varied slightly in

conjunction, from one process colour to another, in order to minimize moiré patterns.

NOTE 2 With non-periodic screens, reliable results are obtained if the minimum dimension of the image elements is

40 µm.
4.2.4 Screen angle

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

magenta (M) and black (K) shall be 30°, with the screen angle of yellow separated at 15° from any other

colour. The screen angle of the dominant colour should be 45°.

For half-tone dots with a principal axis, the nominal difference between screen angles for cyan, magenta and

black shall 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 135°.
...

SLOVENSKI STANDARD
SIST ISO 12647-3:2006
01-september-2006

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SUHVNXVQLKLQSURL]YRGQLKRGWLVRY±GHO3URFHVLYþDVRSLVQHPRIVHWQHPWLVNX
QDURWDFLMDKVKODGQLPVXãHQMHP

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 12647-3:2005
ICS:
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
SIST ISO 12647-3:2006 en

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

---------------------- Page: 1 ----------------------
SIST ISO 12647-3:2006
---------------------- Page: 2 ----------------------
SIST ISO 12647-3:2006
INTERNATIONAL ISO
STANDARD 12647-3
Second edition
2005-10-01
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 12647-3:2005(E)
ISO 2005
---------------------- Page: 3 ----------------------
SIST ISO 12647-3:2006
ISO 12647-3:2005(E)
PDF disclaimer

This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but

shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In

downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat

accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.

Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation

parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In

the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

© ISO 2005

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

electronic or mechanical, including photocopying and microfilm, without permission in writing 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 2005 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 12647-3:2006
ISO 12647-3:2005(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 file, colour separation films and printing formes ..................................................................... 2

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

4.4 Additional requirements for single-colour reproduction and printing.......................................... 10

5 Test method: tone value and tone value increase of a print.......................................................... 10

Annex A (informative) Tolerances for the secondary colour solids ........................................................... 11

Annex B (informative) Densities of ink set colours ...................................................................................... 12

Annex C (informative) Characterization data for 26 % and 30 % tone value increase .............................. 13

Annex D (informative) Grey balance............................................................................................................... 14

Bibliography ..................................................................................................................................................... 15

© ISO 2005 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 12647-3:2006
ISO 12647-3:2005(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 12647-3 was prepared by Technical Committee ISO/TC 130, Graphic technology.

This second edition cancels and replaces the first edition (ISO 12467-3:1998) which has been technically

revised, in particular the tone value increase values specified, as borne out by the print characteristic curves

of Figure 3. Parameters of all process steps have to be adjusted to achieve these curves; they apply

irrespective of whether a positive or a negative acting plate making process is used. The reference to

letterpress has been removed completely. Some solid colour CIELAB values have been changed slightly in

response to demands from the field.

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

the production of half-tone colour separations, proofs 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
iv © ISO 2005 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 12647-3:2006
ISO 12647-3:2005(E)
Introduction

When producing a half-tone colour reproduction it is important that the colour separator, proofer 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") and subsequent production of off-press or on-press

proof prints from these separations whose purpose is to simulate the visual characteristics of the finished print

product as closely as possible.
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 proof or production

print produced by coldset offset lithography on newsprint, or half-tone proof designed to simulate this, from a

set of half-tone separation films.

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 or proof produced

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

recommended for specification.

Since non-periodic screening and direct-to-plate techniques are common practice within newspaper printing,

information on some of the pertinent parameters has been included.
© ISO 2005 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 12647-3:2006
---------------------- Page: 8 ----------------------
SIST ISO 12647-3:2006
INTERNATIONAL STANDARD ISO 12647-3:2005(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

preparing colour separations for newspaper single or four-colour printing and proofing. The parameters and

values are chosen in consideration of the complete process, covering the process stages: “colour separation”,

“film setting”, “making of the printing forme”, “proof production” and “production printing”.

This part of ISO 12647 is applicable:

⎯ to coldset offset proof and production printing and off-press proof printing processes on newsprint that

use colour separation films rather than digital data;

⎯ by analogy to press printing from printing surfaces produced by direct imaging methods and the

corresponding proof printing processes.
⎯ It is not applicable:

⎯ to line screens and non-periodic screens although certain parameters given can be applied by analogy. In

particular, the tone value increases specified, apply directly because they refer to control patches that

contain periodic screen half-tones;

⎯ to flexo and letterpress production printing although a number of parameters can be applied by analogy.

2 Normative references

The following referenced documents are indispensable for the application 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 — Density measurements — Part 3: Spectral conditions

ISO 8254-1, Paper and board — Measurement of specular gloss — Part 1: 75 degree gloss with a converging

beam, TAPPI method

ISO 12647-1:2004, Graphic technology — Process control for the production of half-tone colour separations,

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

ISO 15930-4, Graphic technology — Prepress digital data exchange using PDF — Part 4: Complete exchange

of CMYK and spot colour printing data using PDF 1.4 (PDF/X-1a)

ISO 15930-6, Graphic technology — Prepress digital data exchange using PDF — Part 6: Complete exchange

of printing data suitable for colour-managed workflows using PDF 1.4 (PDF/X-3)
© ISO 2005 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 12647-3:2006
ISO 12647-3:2005(E)
3 Terms and definitions

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

3.1
coldset offset lithography

method of offset lithographic printing where the inks set ("dry") primarily by absorption into the print substrate

4 Requirements
4.1 General

The following subclauses are arranged according to the order set out in ISO 12647-1. They also depend on it

for the definition of the parameters and test methods.

If data files or colour separation film sets are supplied for printing they should be accompanied by a proof print

that simulates the intended production printing condition to a sufficient degree. This fact shall be verifiable by

measuring a well-known control strip or a similar control device that is printed on the proof print along with the

subject.
4.2 Data file, colour separation films and printing formes
4.2.1 General

Electronic data should be delivered as PDF/X-1 or PDF/X-3 data files as defined in ISO 15930-4 or

ISO 15930-6. Where film is supplied, the intended receiver of the film shall specify the tone value curve for

which the film shall be prepared.
4.2.2 Film or printing forme quality

The tone values for film and printing formes shall be adjusted such that, for all primary colours, the tone value

increase from data to paper conforms to one of the two curves specified in 4.3.4.1. Within an ink set, the

printed characteristics of all the primary printing ink colours shall conform to the same tone value curve.

NOTE 1 Data sender and receiver need to agree on which of the two curves specified in Table 5 and shown in Figure 3

will be used. The choice of the appropriate curve for common use is generally made by national or international trade

associations.

NOTE 2 Methods for tone value adjustments include setting of the RIP look-up table, choosing a suitable blanket type,

suitable setting of the plate to blanket pressure and adjustment of the ink rheology.

EXAMPLE 1 Conventional plate making with negative film produces a tone value increase of 33 % in the mid tone. In

order to achieve 26 %, the RIP look-up table was adjusted by − 4 % and the choice of a different ink generated a 3 %

lower tone value increase. These two adjustments lowered the tone value increase to 26 %. If 30 % is to be achieved, less

adjustments are necessary to reach the correct tone value increase.

EXAMPLE 2 With a given CTP system the tone value increase was found to be 22 %. An increased blanket to plate

pressure yielded + 2 %, the remaining + 2 % were introduced at the RIP look-up table; 26 % tone value increase was

achieved.

The resolution of the film or plate setter should be set to 500 cm and shall not be set to a lower value than

472 cm in order to assure a sufficient number of generated tone value steps.

The deviation of tone values over the complete printing forme shall not exceed ± 2 %. The deviation range of

the measuring device (densitometer or camera-based device) shall be added to this value.

2 © ISO 2005 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 12647-3:2006
ISO 12647-3:2005(E)

Unless otherwise specified, the core density of a colour separation film shall be at least 2,5 above the

transmission density of the clear film (film base plus fog). The transmission density in the centre of a clear

half-tone dot shall not be more 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.
The fringe width of a colour separation film shall not be greater than 6 µm.

The colour separation film quality should be evaluated according to Annex B of ISO 12647-1:2004.

Measurements shall be made with a (UV) transmission densitometer whose spectral products conform to

ISO type 1 printing density as defined in ISO 5-3; for the evaluation of core properties, type 2 printing density

may be used.

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 on to an offset plate, for consistent work, should not exceed 0,10.

NOTE 3 As a practical guide, a core density of 2,5 above the clear film density will normally be achieved if the density

of large solid areas is more than 3,5 above the clear film density.

NOTE 4 With non-periodic screens, a fringe width of not more than 4 µm is reported to give reliable results.

4.2.3 Screen frequency

For four-colour work, the screen frequency should be (40 ± 2) cm . Within the same copy of a newspaper,

the screen ruling shall be the same for colour and black-and-white printing. If, as an exception, other screen

rulings are used, the tone value increase shall be adjusted such that it agrees with Table 5 and Figure 3.

NOTE 1 With computer-generated screening, the parameters screen ruling and screen angle can be varied slightly in

conjunction, from one process colour to another, in order to minimize moiré patterns.

NOTE 2 With non-periodic screens, reliable results are obtained if the minimum dimension of the image eleme

...

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