SIST-TS ISO/TS 21328:2023

SLOVENSKI STANDARD
01-april-2023
Grafična tehnologija - Smernice in priporočila za karakterizacijo večbarvnega
(CMYKOGV) tiska
Graphic technology — Guidelines and recommendations for multicolour (CMYKOGV)
print characterization
Technologie graphique — Lignes directrices et recommandations pour la caractérisation
de l'impression en couleurs à gamme étendue (CMYKOGV)
Ta slovenski standard je istoveten z: ISO/TS 21328:2022
ICS:
37.100.01 Grafična tehnologija na Graphic technology in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL ISO/TS
SPECIFICATION 21328
First edition
2022-08
Graphic technology — Guidelines and
recommendations for multicolour
(CMYKOGV) print characterization
Reference number
© ISO 2022
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Guidelines and requirements associated with specific tasks . 3
4.1 Basic support requirements . 3
4.1.1 Viewing conditions . 3
4.1.2 Measurement and colour computation . 3
4.1.3 Data evaluation tools . 3
4.2 Colour definition . 3
4.2.1 Process colours . 3
4.2.2 Pigment Selection . 4
4.2.3 Substrate selection . 4
4.3 Colorimetric/spectral data reporting . 5
4.4 Printing for the development of characterization data . 5
4.4.1 Input data for characterization of multicolour printing . 5
4.4.2 Printing device setup . 5
4.4.3 Printing device verification . 5
4.4.4 Colour Communication . 5
4.4.5 Verification and reporting . 5
Annex A (informative) Example of colour characterization procedures . 7
Annex B (informative) Colour characterization process .10
Annex C (informative) Ink pigment specification for multicolour system .11
Bibliography .12
iii
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
Introduction
Multicolour process packaging printing
Print technology and quality has improved in the past decades. Mechanical print characteristics perform
at a higher level, as have customer expectations. For cyan, magenta, yellow, and black (CMYK), colour
standardization has been adopted and customers expect a specific colour gamut and conformance to
a characterization data set when printing with CMYK. The result of technology integration in all print
processes has provided improvement in productivity and print quality. The research of Neugebauer
[18] [17] [22]
(1937) , Murray (1936) , and Yule (1967) presented a view of colour reproduction, which has
evolved from imaging systems based on silver halide photography technology leading to today’s digital
pixel-by-pixel access to colour image data.
Print systems have also evolved from four-colour (CMYK) on four unit presses to CMYK plus additional
colours as noted in research and recognized patents. Often called multicolour process printing (MCPP),
additional terms used are Extended Colour Gamut (ECG) printing, Expanded Gamut Printing (EGP),
Fixed-palette (FP) printing, N-colour printing, High-Fidelity (HiFi) printing. Examples of research
[20] [9] [16]
include Kueppers (1989), Mills Davis/HiFi project (1991), Ostromoukhov , Boll , Mahy & De Baer ,
[21]
Bernasconi (1998), Herbert and DiBernardo (1998), Lo (1997), Viggiano and Hoagland , and Ingram
[14]
and Simon . In most of these references, additional colours were added to enhance image elements
of the selected CMYK ink set. Viggiano and Hoagland provide methodology for colourant selection.
Package printing often requires spot colours to be matched to aims within tolerances, with colour
remaining consistent throughout the print run. This document describes insight concerning the
selection of colourants to expand or enhance colour print gamut with orange, green, and violet (OGV)
and recommended characterization procedures. The colourant selection may be restricted by the print
[12]
process characteristics .
Previous efforts recommend adding an ink containing pigment Green, an ink containing Violet, and
an ink containing an orange pigment. Due to ink curing systems, difficulty remains making a specific
[14]
recommendation on a single orange pigment. Clemson University studies by Ingram and Simon , and
[23] [10]
Zeleznik were able to recommend Colour Index International (C.I.) pigment Orange-16 and C.I.
pigment Orange-64. C.I. values are a common database reference for manufactured colour products,
which can be communicated based upon a specific source. The recommended CMYKOGV pigment set
provides increased colour gamut as seen in the colour gamut comparison as follows.
[15]
Figure 1 — CIELAB Colour Boundary Comparison of CMYK to CMYKOGV Hue Aims
Use of a standardized multicolour printing target is required. Previous efforts have used an IT8.7/3 or
IT8.7/4 colour characterization target. Four data sets are produced: 1. CMYK, 2. CMVK–complementary
substituted ink, 3. CGYK–complementary substituted ink, and 4. OMYK–complementary substituted
v
ink. The measured spectral data sets were combined to produce a master CMYKOGV data set. A custom
seven-colour characterization target may also be used. The colour data set is then analysed to calculate
the colour gamut fit. Lastly, a technology capable of producing a compatible ICC n-colour profile is
needed to complete a colour-managed workflow utilizing the CMYKOGV data.
vi
TECHNICAL SPECIFICATION ISO/TS 21328:2022(E)
Graphic technology — Guidelines and recommendations
for multicolour (CMYKOGV) print characterization
1 Scope
This document provides guidelines and a procedure to generate a multicolour characterization dataset.
Specifications for colour printing with CMYK + Orange, Green, and Violet are presented. Also, this
document provides a recommendation on CMYKOGV ink pigment selections to produce an optimum
colour gamut for specific printing processes or use cases. The recommended CMYKOGV ink pigment
selections might not be suitable or available for all printing or digital processes or use cases. The
procedure in this document is also applicable for CMYK plus any subset of O, G or V.
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 3664, Graphic technology and photography — Viewing conditions
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ISO 17972-1, Graphic technology — Colour data exchange format — Part 1: Relationship to CxF3 (CxF/X)
ISO 28178, Graphic technology — Exchange format for colour and process control data using XML or ASCII
text
ISO/TS 19303-1, Graphic technology — Guidelines for schema writers — Part 1: Packaging printing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
calibration
comparison and adjustment between printing systems – one of known behaviour or correctness, made
with a set of reference colours, and another printing system made to print in as similar a way as possible
with the reference device
Note 1 to entry: The G7 methodology is one form of printing system calibration where the reference colours are
3-colour overprints made to match as closely as possible the optical properties of a series of black-only prints.
Note 2 to entry: ISO/PAS 15339-1 describes another process for calibration of a printing system to a Characterized
Reference Printing Condition.
Note 3 to entry: Often, the first step alone in the above definition is perceived as being calibration.
3.2
colour characterization data
tabulation of data that represents the relationship between device code values (e.g. CMYK, CMYKOGV)
and the colour (spectral and CIELAB values) produced on the printed sheet by those values in a specific
printing process
Note 1 to entry: The colour characterization data may be used to create an ICC profile as in ISO 15076.
3.3
Colour eXchange Format
CxF/X
format for the communication of colour and process control data and the associated metadata for its
proper interpretation detailed in ISO 17972-1
Note 1 to entry: For example, CxF/X-1 is used to communicate process colour information and other metadata
related to the colour data including tone values, ink amounts and spectral data. CxF/X-4 files are used to
communicate spot colour ink data that requires spectral data and transparency metadata.
3.4
hue angle
angular component of the polar representation of a colour based on CIELAB, calculated by h =
ab
arctangent(b*/a*)
3.5
printing condition
set of primary process parameters that describe the conditions associated with a specific printed
output and defined colourimetrical and/or densitometrical aim values
3.6
packaging
process of designing, evaluating, and producing packages
Note 1 to entry: For this document, use of the term specifically refers to the materials used to produce colour
graphics and information displayed on the substrate.
Note 2 to entry: Methods for production may include direct printing, lamination, or labels.
3.7
primary process colour
colour that is the outcome of a colour separation process (typically CMYK)
Note 1 to entry: A process colour reproduction typically requires one or more printing units and process inks to
be reproduced.
Note 2 to entry: The ink set is specified in the ISO 12647series.
Note 3 to entry: The colours OGV are typically added in MCPP.
3.8
characterized reference printing condition
CRPC
identified printing condition (3.11) and its colour characterization data used as the aim for a
particular printing task (job)
Note 1 to entry: ISO/PAS 15339-1 provides 7 Characterized Reference Printing Conditions (CRPC).
3.9
spot colour tone value
SCTV
value that describes the apparent halftone area for a non-process ink as described in ISO 20654
3.10
multicolour process printing
MCPP
printing with more than a single colour ink with a multi-unit printing system
Note 1 to entry: It is also called expanded colour gamut printing where process colour printing uses more than 4
primary inks, for example orange, green, and violet inks, so as to increase the volume of colour space which can
be reproduced using halftone combinations of the primary plus extra inks.
3.11
identified printing condition
printing condition documented in a national or international standard or industry publication in a
way that allows it to be replicated by an industry practitioner. Also, a set of primary process parameters
that describe the conditions associated with a specific printed output and defined colourimetrical and/
or densitometrical aim values
4 Guidelines and requirements associated with specific tasks
4.1 Basic support requirements
4.1.1 Viewing conditions
The viewing and illumination conditions used for visual assessment of printed products shall be in
accordance with ISO 3664.
4.1.2 Measurement and colour computation
The measurement of colour shall be made with instruments, standardized according to the
manufacturer’s guidelines and capable of producing data in accordance with ISO 13655. Further, it is
recommended that ISO 20654 should be used to determine tonal values, also CMYK near neutral or
TVI methods are applicable. When substrate corrections are necessary, calculations should follow
ISO/PAS 15339-1. When the OBA content is high or moderate and the expected viewing condition
contains UV, measurements shall be made with M1 measuring mode. When the OBA content is low or
faint (i.e. UV-UVX ≤8 when measured D65 Brightness with UV and with UV cut-off filter), M0, M1 or
M2 may be used since comparable results are expected. Where the expected viewing condition doesn't
contain UV, the use of M2 is recommended.
NOTE When viewing in a UV fre
...