ISO/PAS 15339-1:2015
(Main)Graphic technology — Printing from digital data across multiple technologies — Part 1: Principles
Graphic technology — Printing from digital data across multiple technologies — Part 1: Principles
ISO/PAS 15339-1:2015 establishes principles for the use of colour characterization data as the definition of the intended relationship between input data and printed colour for copy preparation, job assembly, proofing, and graphic arts production printing. Additional parts of ISO/PAS 15339 specify a limited number of characterized reference printing conditions that span the expected range of colour gamuts used for the production of printed material from digital data, regardless of printing process used. The procedure to be used to adjust colour characterization data for the normally expected range of substrate colour is specified.
Technologie graphique — Impression à partir de données numériques via des technologies multiples — Partie 1: Principes
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Standards Content (Sample)
PUBLICLY ISO/PAS
AVAILABLE 15339-1
SPECIFICATION
First edition
2015-08-15
Graphic technology — Printing
from digital data across multiple
technologies —
Part 1:
Principles
Technologie graphique — Impression à partir de données numériques
via des technologies multiples —
Partie 1: Principes
Reference number
ISO/PAS 15339-1:2015(E)
©
ISO 2015
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ISO/PAS 15339-1:2015(E)
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ISO/PAS 15339-1:2015(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 Principles and assumptions . 2
4.2 Data encoding . 2
4.3 Data preparation . 3
4.4 Characterized reference printing conditions and colour characterization data . 3
4.5 Use selection criteria for choice of characterized reference printing condition . 3
4.6 Adjustment of data for substrate colour differences . 4
4.7 Alternate printing reference. 4
4.8 Colour profiles . 4
5 Process control . 5
5.1 General . 5
5.2 Printing to intended gamut . 5
5.3 Determine colour characterization . 6
5.4 Maintain running characteristics of the printing device . 6
5.4.1 Tools and procedures . . 6
5.4.2 Tolerances . 7
5.5 Job content specific adjustments . 7
Annex A (normative) Correction of colorimetric data for variation in substrate colour .8
Annex B (informative) Tolerancing schema .10
Annex C (informative) Process independent workflow .14
Bibliography .15
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ISO/PAS 15339-1:2015(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 130, Graphic technology.
ISO/PAS 15339 consists of the following parts, under the general title Graphic technology — Printing
from digital data across multiple technologies:
— Part 1: Principles [Publicly Available Specification]
— Part 2: Characterized reference printing conditions, CRPC1–CRPC7 [Publicly Available Specification]
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ISO/PAS 15339-1:2015(E)
Introduction
ISO/PAS 15339 is based on the premise that in the printing and publishing industries, electronic data are
the intermediary for content storage and exchange throughout production including copy preparation,
job assembly, proofing, and process colour printing. It further assumes that data preparation can be
largely process independent and that choice of the printing process or processes to be used for final
production will be based primarily on run length requirements and substrates to be used. There
are various tools in place to both define the relationship of digital data to printed colour for specific
instances of printing and to manipulate data such that similar results can be obtained between and
among different printing processes (ISO/TS 10128). These specific instances of printing are typically
described by colour characterization data, which is the relationship between CMYK input data and
colour measured on the printed sheet. Where such a set of colour characterization data are used as a
reference, it is referred to as a characterized reference printing condition (CRPC).
When producing printed colour reproductions it is important that the organizations responsible
for material preparation, colour separation, proofing, and printing all working to a common set of
parameters that uniquely define the intended visual characteristics of the final printed product. Such
an agreement enables the correct production of suitable input data and subsequent production of
proofs from these data. The purpose of a proof is to simulate the visual characteristics of the finished
print product as closely as possible prior to production printing.
There is a unique relationship between ink, substrate, and printing process that limits the maximum
chroma of the solids of the printing colorants and therefore limits the range of colours (colour gamut)
that can be achieved for particular combinations. While special inks can be used, the commonly
available ink pigments are used across all traditional ink processes. While toner and ink-jet systems
have different colorant constraints than traditional ink processes, they tend to mimic traditional
ink process aims and they will be treated as a variation of traditional ink processes. The achievable
chroma range (gamuts) of ink-on-paper characterized reference printing conditions can generally be
bracketed between cold-set printing on newsprint on the small end and by printing on gloss coated
stocks (by a variety of processes) on the large end. Between these limits there is significant overlap
of process/substrate combinations. The number of intermediate characterized reference printing
conditions that are logical to define between smallest and largest is in part a function of the tolerances
to which printing is expected to conform to the intended characterized reference printing condition.
However, the intermediate characterized reference printing conditions also need to represent common
widely used printing and that was the determining factor for the selection of the characterized reference
printing conditions listed in ISO/PAS 15339-2. In addition, a characterized reference printing condition
7 is included to represent a possible exchange space for large gamut processes that exceed the colour
gamut of characterized reference printing condition 6 and therefore need a larger reference gamut.
The data sets defined in ISO/PAS 15339-2 are those associated with the initial publication of ISO 15339.
It is the intent of ISO/TC 130 that if changes in, or additions to, these data sets are needed in the future
they will be documented in added parts of ISO/PAS 15339 so that changes in the data sets, or addition
of data sets, are possible without losing traceability to earlier data sets.
A colour characterization data set is required for each characterized reference printing condition
specified. Because the intent of ISO/PAS 15339 is that the data sets provided can be used as the reference
for any printing process, they might not be aligned with the typical TVI and trapping associated with
any specific printing process. The values selected need to represent a compromise between all potential
processes to be used – in effect virtual printing on a virtual printing system.
It is important to realize that digital data can be encoded as already separated CMYK or can consist
of un-separated data (typically in an RGB colour space) with supplementary information (ICC colour
profiles, etc.) defining the colour intended on the printed sheet. Such unseparated data plus the
associated supplementary data are sometimes referred to as “virtual CMYK” data. All data are to
be encoded according to one of the PDF/X specifications (ISO 15930- series) to allow the necessary
metadata which identifies the intended characterized reference printing condition to be included.
The colour of the printing substrate is a critical component of the colour appearance of a printed image
(it behaves like a 5th colour). With the current widespread use of optical brightening agents (OBA)
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ISO/PAS 15339-1:2015(E)
substrate colour is defined in terms of its apparent reflectance under D50 illumination (see ISO 3664).
For halftone images the colour of the substrate contributes mostly in the area not covered by ink.
ISO 13655 provides a reasonably effective method to adjust tristimulus data of measured halftone
areas for moderate changes in substrate colour. ISO/PAS 15339 is based on the assumption that the
colour characterization data can be adjusted (fine-tuned) for the range of normal substrate colours
expected and that different characterized reference printing conditions are not required for moderate
differences in substrate colour.
Although density, tone value increase, grey balance, etc. are individually important tools for the
printing and publishing industry, in ISO/PAS 15339 they are assumed to be part of process control and
not printing definition. They need to be considered in developing reference colour characterization
data sets and need to be used where applicable as part of local site ongoing process control.
Modern characterization data and profile evaluation tools allow identification of the colour of the solids,
the colour and tone values of the single colour scales, and the CMY values associated with the neutral
(achromatic) tone scale. Using the values derived from the colour characterization data, rather than any
a priori values, is the recommended input for process control aims used to control a printing process
intended to conform to a particular characterized reference printing condition.
Annex C provides a description of the process independent workflow that is the basis for the concepts
embodied in ISO/PAS 15339.
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PUBLICLY AVAILABLE SPECIFICATION ISO/PAS 15339-1:2015(E)
Graphic technology — Printing from digital data across
multiple technologies —
Part 1:
Principles
1 Scope
This part of ISO/PAS 15339 establishes principles for the use of colour characterization data as the
definition of the intended relationship between input data and printed colour for copy preparation, job
assembly, proofing, and graphic arts production printing. Additional parts of ISO/PAS 15339 specify a
limited number of characterized reference printing conditions that span the expected range of colour
gamuts used for the production of printed material from digital data, regardless of printing process
used. The procedure to be used to adjust colour characterization data for the normally expected range
of substrate colour is specified.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 10128, Graphic technology — Methods of adjustment of the colour reproduction of a printing
system to match a set of characterization data
ISO 12642-2, Graphic technology — Input data for characterization of 4-colour process printing — Part 2:
Expanded data set
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ISO 15076-1, Image technology colour management — Architecture, profile format and data structure —
Part 1: Based on ICC.1:2010
ISO 15930 (all parts), Graphic technology — Prepress digital data exchange using PDF
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply
3.1
colour characterization data
tabulation of data that represents the relationship between device code values (e.g. CMYK) and the
colour (CIELAB) produced on the printed sheet by those values in a specific printing process
3.2
colour profile
set of transforms, encoded according the rules of ISO 15076-1, that convert data between (to and from)
device space and profile connection space
Note 1 to entry: The transforms contained within a colour profile can include manipulation of gamut
compression/expansion, tone reproduction, colour separation, black printer creation, printing limitations (e.g.
total area coverage), etc.
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ISO/PAS 15339-1:2015(E)
3.3
gamut
region of CIELAB colour space containing all printable colours
Note 1 to entry: For comparison purposes the CIELAB values of the primaries and secondaries along with the
substrate are often an adequate, if sparse, definition of a colour gamut. The surface values of the measurements
of a target such as that included in ISO 12642-2 can provide a more complete definition.
3.4
characterized reference printing condition
CRPC
identified printing condition and its colour characterization data used as the aim for a particular
printing task (job)
3.5
process independent
independent of the printing process (offset, flexography, gravure, etc.), to be used for production of
printed material
3.6
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
4 Requirements
4.1 Principles and assumptions
One of the key principles upon which ISO/PAS 15339 is based is that colour content data can be adjusted
such that any printing processes, capable of achieving a specified colour gamut, can produce the within-
gamut image colours specified by the appropriate reference colour characterization data. This allows
printing aims to be process independent.
A second principle is that process control aims and tools should be based on (extracted from) the
reference colour characterization data selected and not based on a priori assumptions. Many of the
parameters used in process control such as tone value increase, grey balance, etc. are contained within,
or can be derived from, the colour characterization data chosen as reference. Local site tools can also be
used for initial setup processes, but these need to be based on the known differences between the colour
characterization data aims and the colour characterization of the actual printing system being used.
Where similar characteristics, such as tone reproduction, are desired between different characterized
reference printing conditions (different colour gamuts) these need to be built into the colour
characterization data associated with these characterized reference printing conditions. Characterized
reference printing conditions, and their associated colour characterization data, can be thought
of as a virtual printing system (press) and as such the characterization data can be manipulated
mathematically to fine tune results to achieve smoothness, uniformity and/or other characteristics.
The key requirement for successful application of these principals is that the reference colour
characterization data and the characterization data for the printing system being used shall have
the same gamut and be sufficient to allow the necessary data adjustment (see ISO/TS 10128 for
recommended procedures to implement such data adjustment).
4.2 Data encoding
In the absence of other prior agreement, electronic colour content data to be used as the intermediate
storage and exchange media between copy preparation, job assembly, proofing, and printing shall be
encoded in accordance with ISO 15930. Any deviation from this, such as encoding in ISO 12639 or in
some other format, shall be according to prior agreement by all parties, and shall include communication
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ISO/PAS 15339-1:2015(E)
of the reference characterization data of the intended printing condition and, as necessary, a colour
profile to transform any data not supplied in the process colour model of the reference.
4.3 Data preparation
All print elements shall be prepared either as device code values or as colorimetrically defined data.
However, both types of data if present in print elements shall be prepared for a single characterized
reference printing condition. This condition shall be provided in the PDF/X output intent in the case of
an ISO 15930 exchange, or shall be communicated by mutually agreed upon methods in other situations.
Unless otherwise agreed between sender and receiver, the characterized reference printing condition
shall be one of the data sets defined in ISO/PAS 15339.
4.4 Characterized reference printing conditions and colour characterization data
The characterized reference printing conditions associated with this part of ISO 15339 are contained in
additional parts of ISO/PAS 15339. This approach was taken to allow ISO/TC 130 to change or update
characterized reference printing conditions without revising or invalidating characterized reference
printing conditions that might have been used as the basis for existing printing work.
The data sets defined in ISO/PAS 15339-2 (CRPC1–CRPC7) are those associated with the initial
publication of ISO 15339.
NOTE If changes in, or additions to these data sets are needed in the future, they can be documented in
added parts of ISO/PAS 15339 and carry new CRPC designations. When additional CRPCs are published in
subsequent parts of ISO/PAS 15339, it is expected that they will follow the same sequential naming scheme to
avoid confusion, i.e. ISO15339-CRPC8 would be the next named data set.
For alternate printing processes that do not use colorants that align with the hue angles of a
characterization data set, the colour values may be simulated by the appropriate combination of
the colorants available, assuming the colour gamut of those colorants encompasses the gamut of the
characterized reference printing condition selected. For convenience this part of ISO/PAS 15339 will
continue to refer to single-colour solids, two-colour overprints, etc. recognizing that alternate printing
systems may simulate these values using appropriate combinations of available colorants.
All colorimetry should be measured according to ISO 13655, M1 with white backing. Where the
substrate is non-fluorescent M1 data are identical to M0 data and M0 data may be used as M1 data. If
M1 data are not available, M0 data converted to M1 is sufficient (see Annex A).
The measurement conditions and intended interpretation of all colorimetric data provided as part of
ISO/PAS 15339 CRPCs (ISO/PAS 15339-2 and future parts) shall be defined in the part of ISO/PAS 15339
in which the data appears.
The characterized reference printing conditions shown in ISO/PAS 15339-2 have been selected to be
near the middle of both the general class of printing that is expected to make use of each characterized
reference printing condition and the colour of the substrates used. It is expected that adjustments for
substrate colour (see 4.6) will allow each characterized reference printing condition to meet a wide
variety of needs and be independent of the printing process to be used.
4.5 Use selection criteria for choice of characterized reference printing condition
It is anticipated that the printing industry (with support from the ink and paper organizations) will
begin to develop tables of substrate types and printing processes that will support and/or be most
appropriate for each of the characterized reference printing conditions. Where the same content is to be
reproduced by more than one process or on more than one substrate a gamut common to the multiple
needs should be selected. Where only a single substrate and printing system is to be used, the typical
choice should be the largest gamut that choice will support.
The chosen characterized reference printing condition shall be used as the basis for design and
content creation.
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ISO/PAS 15339-1:2015(E)
Communication of the intended printing condition between all parties (preparation, proofing, and
printing) only needs to identify ISO/PAS 15339 and the gamut to be used along with information relating
to any limitations of the intended printing process that need to be considered during preparation,
proofing, or printing.
Not all printing processes that can achieve the same colour gamut are subject to the same limitations.
Offset, gravure, flexography, electrophotographic, ink-jet, etc., each have limitations that may have to
be considered in the final data preparation for printing. These typically include limitations of total ink
coverage, minimum and maximum printable dot sizes, etc.
NOTE If general guidance is needed, additional parts of ISO/PAS 15339 can be prepared to assist in the
communication or standardization of the handling of such limitations.
4.6 Adjustment of data for substrate colour differences
The characterization data contained in ISO/PAS 15339-2 are all based on the CMYK characterization
target defined in ISO 12642-2. The substrate colour is therefore given in data element 1 of each data set.
Where the printing substrate to be used has a colour that differs from that of the reference printing
condition selected for data preparation and data exchange, correction of the data for such differences
can be beneficial. The use of a single method to accomplish correction enhances the ability of different
users to achieve similar results. Annex A provides one conversion method that produces reasonable
results for halftone type images. Where substrate adjustment is done this fact, the method used (if
other than Annex A), and the values of the intended substrate shall be communicated to all involved.
Where the printing substrate to be used has a colour that differs from that of the reference printing
condition selected for data preparation and data exchange by less than 2 CIEDE2000 the user can elect
to use the data without modification.
Where the printing substrate to be used has a colour that differs from the characterized reference
printing condition selected for data preparation and data exchange by more than 2 but less than 5
CIEDE2000 the method defined in Annex A (see also ISO 13655) should be used to adjust the data before
proofing and printing.
Where the difference in substrate colour is greater than 5 CIEDE2000, this correction may be used but
the user is cautioned that special colour characterization data might be required which is beyond the
scope of ISO/PAS 15339.
When data adjustment is done using the tristimulus correction technique defined in Annex A, the colour
values of all data points in the colour characterization data set are changed, including the aim values for
the single colour solids.
Where characterization data are exchanged that has been modified for changes in substrate colour, it
can no longer be simply referenced as ISO 15339, CRPCx. Where the exchange between participants is
not a blind exchange, agreements concerning the substrate to be used and the substrate correction can
be exchanged and included in private metadata. For blind exchange it can be treated as an alternate
printing reference (see 4.7).
4.7 Alternate printing reference
Where one of the sets of reference colour characterization data defined in the additional parts of
ISO/PAS 15339 are not appropriate for the intended printing because of the inks, paper, or printing
process to be used, prior agreement should be obtained between all parties involved before copy
preparation work is started and the colour characterization data to be used and any colour management
profiles shall be communicated with the job content files.
4.8 Colour profiles
The use of colour profiles is an important part of the data preparation process and colour profiles with
specific characteristics are often specified by industry trade associations to restrict and provide more
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ISO/PAS 15339-1:2015(E)
commonality in user input. It is important that colour characterization data and colour management
profiles
...
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