ISO 23498:2020

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.

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SIST ISO 23498:2021

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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

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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
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Published in Switzerland
ii © ISO 2020 – All rights reserved

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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

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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
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electrotechnical standardization.
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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
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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
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iv © ISO 2020 – All rights reserved

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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
ab
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.
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