Graphic technology - Visual opacity of printed white ink

This document specifies a method of measuring the visual opacity of printed specimens of white ink. It is applicable to printing opaque white ink on transparent and white or coloured opaque substrates.

Technologie graphique -- Opacité visuelle de l'encre blanche imprimée

Grafična tehnologija - Vizualna opaciteta pri tiskanju z belo tiskarsko barvo ali črnilom

General Information

Status
Withdrawn
Publication Date
09-Jun-2021
Withdrawal Date
19-Feb-2023
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
30-Jan-2023
Due Date
22-Feb-2023
Completion Date
20-Feb-2023

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SLOVENSKI STANDARD
SIST ISO 23498:2021
01-julij-2021

Grafična tehnologija - Vizualna opaciteta pri tiskanju z belo tiskarsko barvo ali

črnilom
Graphic technology - Visual opacity of printed white ink
Technologie graphique -- Opacité visuelle de l'encre blanche imprimée
Ta slovenski standard je istoveten z: ISO 23498:2020
ICS:
37.100.01 Grafična tehnologija na Graphic technology in
splošno general
87.080 Barvila. Tiskarske barve Inks. Printing inks
SIST ISO 23498:2021 en

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

---------------------- Page: 1 ----------------------
SIST ISO 23498:2021
---------------------- Page: 2 ----------------------
SIST ISO 23498:2021
INTERNATIONAL ISO
STANDARD 23498
First edition
2020-09
Graphic technology — Visual opacity
of printed white ink
Technologie graphique — Opacité visuelle de l'encre blanche
imprimée
Reference number
ISO 23498:2020(E)
ISO 2020
---------------------- Page: 3 ----------------------
SIST ISO 23498:2021
ISO 23498:2020(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 23498:2021
ISO 23498:2020(E)
Contents Page

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

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

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

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

3 Terms and definition ........................................................................................................................................................................................ 1

4 Requirements .......................................................................................................................................................................................................... 1

4.1 General ........................................................................................................................................................................................................... 1

4.2 Specimen preparation ...................................................................................................................................................................... 2

4.2.1 General...................................................................................................................................................................................... 2

4.2.2 Printing on transparent substrates .................. ................................................................................................ 2

4.2.3 Printing on the test substrate ............................................................................................................................... 3

4.2.4 Printing on production substrate ...................................................................................................................... 3

4.3 Measurements ......................................................................................................................................................................................... 4

4.4 Calculation of opacity ........................................................................................................................................................................ 5

4.4.1 General...................................................................................................................................................................................... 5

4.4.2 Visual opacity .................. .................................................... ................................................................................................ 6

4.4.3 Extension of visual opacity calculation for coloured inks and substrates ..................... 6

5 Reporting ...................................................................................................................................................................................................................... 6

Annex A (informative) Recommendations for testing metrics for opacity of coloured inks

and substrates ......................................................................................................................................................................................................... 8

Bibliography ................................................................................................................................................................................................................................ 9

© ISO 2020 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 23498:2021
ISO 23498:2020(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.

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
---------------------- Page: 6 ----------------------
SIST ISO 23498:2021
ISO 23498:2020(E)
Introduction

Methods for measuring the transparency or opacity of printing inks and paints have been described

[1]–[4] [1]

in a number of publications . Standard methods for paints are based on the reflectance of the

colorant when printed over a black background relative to the reflectance of the black background

without coloration. The contrast ratio method described in Reference [1] is widely used in the industry

for evaluating opacity, but results can vary significantly depending on how it is used especially where

white ink printed upon on transparent substrates are measured, or where a standard test substrate is

not used.

Methods of measuring opacity and transparency are based on the reflectance of printed and unprinted

areas of a substrate. Reflectance is defined as the luminous reflectance factor and expressed as the

CIE Y tristimulus value, which is not as perceptually uniform as other derived CIE colour spaces such

as 1976 CIELAB. Transparency is related to opacity but is not equal or equivalent to opacity. ISO 2846-1

includes a measure of transparency.

In the transparent imaging model introduced from PDF 1.4, objects can be less than fully opaque, and

all of the objects in a stack can potentially contribute to the final appearance of the page. PDF uses the

term "solidity" rather than opacity, but these terms are essentially the same. An opacity or "solidity"

value of 1,0 describes an ink that completely hides the inks beneath, while a value of 0,0 describes a

[5]

transparent ink that completely reveals the inks beneath , for example a clear varnish. Document

creators specify the opacity of one or more inks, and anticipate that this specified opacity is consistent

with the visual appearance of both preview and final print. This document is intended to be used

to measure the opacity of inks printed using a known configuration of a printing system and so the

measured value is not the opacity of the ink per se but of the ink as printed. This aspect is especially

important when assessing inks printed using inkjet printers. For the opacity value so measured to be

useful, it is important to communicate details of the configuration of the printing system used so that

the printing can be repeated.

There is thus a need for a metric for opacity which has better agreement with visual perception. For

consistency with the PDF model, it is expected that the metric produces values in the range 0 to 100

for fully transparent and fully opaque prints respectively. These requirements exclude the use of the

contrast ratio metric.

The method described in this document was tested using the data reported in Reference [6], and it was

shown to correlate well with the visual perception of opacity.

This document is limited to the opacity of "opaque" white inks, as the published work cited in this

document was limited to the evaluation of such inks. A method is described in Annex A showing how

this document could be extended to test coloured inks. We anticipate that in the future this standard

could be extended if there is a need and adequate experimental data. For this reason, the visual opacity

metric defined in this document is not the simplest formula that fits the experimental data, but is one

that gives good results and can readily be extended to colour inks and substrates if required. The metric

is based on functions used in the Spot Colour Tone Value (SCTV) defined in ISO 20564.

Opaque white inks are formulated to be relatively opaque to light in order to hide any underlying

matter, in contrast to "transparent" white inks which are formulated to permit transmission of light

and are commonly used to extend coloured inks. For the purpose of this document, white ink is an ink

formulated with an opaque white colorant that has a neutral colour and a reflectance factor greater

than 80 %, and which is intended to have high opacity.

This document is also limited in the range of substrates to which it is intended to apply. Substrates

should be either transparent, or have a CIELAB L* lightness of 80 or above and a CIELAB C* chroma of

20 or less.

Various factors can affect the appearance of opacity on a given substrate, including the presence of

optical brightening agents in the ink or substrate, and to minimize such effects, it is assumed that the

material is viewed and measured under standard conditions, where the viewing condition is defined by

[7]
ISO 3664 P1 or P2 condition and the measurement by ISO 13655 M1 condition.
...

INTERNATIONAL ISO
STANDARD 23498
First edition
2020-09
Graphic technology — Visual opacity
of printed white ink
Technologie graphique — Opacité visuelle de l'encre blanche
imprimée
Reference number
ISO 23498:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 23498:2020(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 23498:2020(E)
Contents Page

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

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

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

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

3 Terms and definition ........................................................................................................................................................................................ 1

4 Requirements .......................................................................................................................................................................................................... 1

4.1 General ........................................................................................................................................................................................................... 1

4.2 Specimen preparation ...................................................................................................................................................................... 2

4.2.1 General...................................................................................................................................................................................... 2

4.2.2 Printing on transparent substrates .................. ................................................................................................ 2

4.2.3 Printing on the test substrate ............................................................................................................................... 3

4.2.4 Printing on production substrate ...................................................................................................................... 3

4.3 Measurements ......................................................................................................................................................................................... 4

4.4 Calculation of opacity ........................................................................................................................................................................ 5

4.4.1 General...................................................................................................................................................................................... 5

4.4.2 Visual opacity .................. .................................................... ................................................................................................ 6

4.4.3 Extension of visual opacity calculation for coloured inks and substrates ..................... 6

5 Reporting ...................................................................................................................................................................................................................... 6

Annex A (informative) Recommendations for testing metrics for opacity of coloured inks

and substrates ......................................................................................................................................................................................................... 8

Bibliography ................................................................................................................................................................................................................................ 9

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23498:2020(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.

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
---------------------- Page: 4 ----------------------
ISO 23498:2020(E)
Introduction

Methods for measuring the transparency or opacity of printing inks and paints have been described

[1]–[4] [1]

in a number of publications . Standard methods for paints are based on the reflectance of the

colorant when printed over a black background relative to the reflectance of the black background

without coloration. The contrast ratio method described in Reference [1] is widely used in the industry

for evaluating opacity, but results can vary significantly depending on how it is used especially where

white ink printed upon on transparent substrates are measured, or where a standard test substrate is

not used.

Methods of measuring opacity and transparency are based on the reflectance of printed and unprinted

areas of a substrate. Reflectance is defined as the luminous reflectance factor and expressed as the

CIE Y tristimulus value, which is not as perceptually uniform as other derived CIE colour spaces such

as 1976 CIELAB. Transparency is related to opacity but is not equal or equivalent to opacity. ISO 2846-1

includes a measure of transparency.

In the transparent imaging model introduced from PDF 1.4, objects can be less than fully opaque, and

all of the objects in a stack can potentially contribute to the final appearance of the page. PDF uses the

term "solidity" rather than opacity, but these terms are essentially the same. An opacity or "solidity"

value of 1,0 describes an ink that completely hides the inks beneath, while a value of 0,0 describes a

[5]

transparent ink that completely reveals the inks beneath , for example a clear varnish. Document

creators specify the opacity of one or more inks, and anticipate that this specified opacity is consistent

with the visual appearance of both preview and final print. This document is intended to be used

to measure the opacity of inks printed using a known configuration of a printing system and so the

measured value is not the opacity of the ink per se but of the ink as printed. This aspect is especially

important when assessing inks printed using inkjet printers. For the opacity value so measured to be

useful, it is important to communicate details of the configuration of the printing system used so that

the printing can be repeated.

There is thus a need for a metric for opacity which has better agreement with visual perception. For

consistency with the PDF model, it is expected that the metric produces values in the range 0 to 100

for fully transparent and fully opaque prints respectively. These requirements exclude the use of the

contrast ratio metric.

The method described in this document was tested using the data reported in Reference [6], and it was

shown to correlate well with the visual perception of opacity.

This document is limited to the opacity of "opaque" white inks, as the published work cited in this

document was limited to the evaluation of such inks. A method is described in Annex A showing how

this document could be extended to test coloured inks. We anticipate that in the future this standard

could be extended if there is a need and adequate experimental data. For this reason, the visual opacity

metric defined in this document is not the simplest formula that fits the experimental data, but is one

that gives good results and can readily be extended to colour inks and substrates if required. The metric

is based on functions used in the Spot Colour Tone Value (SCTV) defined in ISO 20564.

Opaque white inks are formulated to be relatively opaque to light in order to hide any underlying

matter, in contrast to "transparent" white inks which are formulated to permit transmission of light

and are commonly used to extend coloured inks. For the purpose of this document, white ink is an ink

formulated with an opaque white colorant that has a neutral colour and a reflectance factor greater

than 80 %, and which is intended to have high opacity.

This document is also limited in the range of substrates to which it is intended to apply. Substrates

should be either transparent, or have a CIELAB L* lightness of 80 or above and a CIELAB C* chroma of

20 or less.

Various factors can affect the appearance of opacity on a given substrate, including the presence of

optical brightening agents in the ink or substrate, and to minimize such effects, it is assumed that the

material is viewed and measured under standard conditions, where the viewing condition is defined by

[7]
ISO 3664 P1 or P2 condition and the measurement by ISO 13655 M1 condition.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 23498:2020(E)
Graphic technology — Visual opacity of printed white ink
1 Scope

This document specifies a method of measuring the visual opacity of printed specimens of white ink.

It is applicable to printing opaque white ink on tran
...

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