SIST ISO 16760:2020

INTERNATIONAL ISO
STANDARD 16760
First edition
2014-12-15
Graphic technology — Prepress
data exchange — Preparation and
visualization of RGB images to be used
in RGB-based graphics arts workflows
Technologie graphique — Échange de données pré-impression —
Préparation et visualisation d’images RGB à utiliser dans les flux de
travail des arts graphiques basés sur le RGB
Reference number
ISO 16760:2014(E)
©
ISO 2014

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ISO 16760:2014(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
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
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ISO 16760:2014(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 RGB workflow overview . 3
4.1 General . 3
4.2 RGB Reference Images . 3
4.2.1 Configuration of RGB workflow . 3
4.2.2 Setup and calibration . 4
4.2.3 Operation procedure . 4
4.2.4 Highlight and shadow point adjustment . 5
4.2.5 Additional data requirements . 5
4.3 Print-simulation workflow . 6
4.3.1 Basic functions of print-simulation workflow . 6
4.3.2 Ways to achieve basic functions . 7
5 File format requirements . 8
5.1 Data delivery . 8
5.2 File format extensions . 8
5.2.1 General. 8
5.2.2 Tiff file . 8
5.2.3 JPEG (JFIF and EXIF) . . 9
5.3 XMP data for approval status.10
6 RGB Reference Prints .11
6.1 Colour measurement and viewing .11
6.2 RGB Reference Print requirements .11
6.2.1 Print substrate colour . . .11
6.2.2 Margin information .12
6.2.3 Print stability .12
6.2.4 RGB digital control strip .12
6.3 Regular checks of RGB Reference Printer .12
6.3.1 Colour requirements .12
6.3.2 Determining aim values .13
6.3.3 Reproduction of vignettes .13
6.3.4 Uniformity test . .13
Annex A (informative) Relationship between highlight and neutral tone value .15
Annex B (normative) Viewing condition .17
Annex C (normative) RGB Reference Print colour test chart .18
Annex D (informative) Key RGB workflow concepts .23
Annex E (informative) Example aim values for common rendering options .29
Annex F (normative) Media relative measurements .30
Annex G (normative) JPEG extension (JPEG-XT) marker segment .32
Bibliography .35
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ISO 16760:2014(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.
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ISO 16760:2014(E)

Introduction
This International Standard provides guidelines for image preparation and print simulation in a graphic
arts print workflow using RGB images (RGB workflow).
Digital still camera (DSC) images have now largely replaced film in the prepress stage of graphic arts
printing and most images printed originate from digital cameras. Standard document exchange using
PDF/X-4 and PDF/X-5 formats supports the use of RGB content and provides a ‘late binding’ printing
solution where colour conversion is performed only when the document is printed. In this way, all of the
original image data can be retained and the conversion for print can be optimised based on the original
image content, key image attributes, and the available press colour gamut. These standard document
formats provide an ideal framework for RGB workflow.
The current best practice for image preparation is to view and adjust images on display. When RGB
images are adjusted, proofing mode is selected for a reference printing condition and a calibrated
monitor is used. In this way, users can see an accurate preview of the printed result. This workflow is
shown in Figure 1.
This document
was made to show
how RGB Workflow
should work.
Figure 1 — Current best practice RGB workflow
There are a number of limitations in this workflow:
— Although it is possible to set up a calibrated monitor and viewing environment defined by
Adobe RGB (1998) Colour Image Encoding or ISO/IEC 61966-2-1, it is not usually the case that
all stakeholders have a calibrated monitor and the same viewing conditions. In the proposed
RGB workflow, an RGB Reference Print can be shared easily among stakeholders.
— For inexperienced users, critical colour judgement on screen is harder than on print and so the
resulting colour might not be what the user desires. The proposed RGB workflow is described for
both experts and inexperienced users.
— The intended printing condition needs to be communicated to every stakeholder by independent
means and all users need to know how to set up a viewing environment appropriate to the printing
condition. In the proposed RGB workflow, the intended printing condition is included as metadata
with the image.
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ISO 16760:2014(E)

— The approval status of an image is not clearly shown. In the proposed RGB workflow, the approval
status is included as metadata with the image.
The proposed RGB workflow addresses these limitations as shown in Figure 2. In this RGB workflow,
candidate images are printed on an RGB Reference Printer that has been calibrated to produce an
accurate simulation of the intended printing condition. These printed images are checked in a controlled
print viewing environment and, if necessary, further adjustments are made until the intended print
result is achieved. When RGB image files are created and checked in this way, metadata that describes
the intended printing condition and the image approval status is added.
CaptureImage preparation Documentcreation and printing
Calibrated to simulate
intended printing
condition
Digital
printer
R’G’B’
Digitalcamera RGB
RGB Reference Image Document Conventional
scene capture Reference
Printcreation approved? creation press
and rendering Image
Digital
press
Add Output intent metadata
Add reference
Retouch
corresponding to
printer’sOutputIntent
intended print condition
Other
Figure 2 — RGB workflow from scene to printing via RGB image data
Careful preparation of RGB images holds the key to a successful RGB workflow. There are a number of
aspects to consider when preparing images for print, including the identification of image highlight and
shadow points and the careful mapping of important image colours into the colour gamut of the printing
press. Since most printing processes have a significantly different colour gamut size and shape from the
set of colours represented in an image, care needs to be taken when editing images so that important
colours are retained. This is done most effectively by associating the RGB image with a CMYK press
profile. This International Standard describes how to prepare these RGB images. Figure 2 shows the
RGB workflow described by this International Standard and R’G’B’ is the prepared RGB image.
NOTE For the proposed workflow, although a calibrated soft proof viewing environment is not required, the
calibration of a reference printer is required and this print needs to be viewed in a standard calibrated viewing
environment. If possible, printers with automatic calibration need to be used in cases where users are not familiar
with the calibration process.
When this workflow is adopted, images can be prepared and incorporated in documents which can be
printed on multiple printing systems producing prints with a similar appearance.
When the RGB image data are approved based on a hardcopy print, consistent judgement can be made.
This workflow is supported by the PDF/X-4 and PDF/X-5 standard document formats. Documents are
expected to be approved using ISO 12647-8 (validation print) or ISO 12647-7 (contract proof).
It is envisaged that printing systems will be developed to produce prints that conform to this International
Standard. It can be the case that systems that already conform to the requirements of ISO 12647-8 or
ISO 12647-7 will be extended to produce RGB Reference Prints. Such systems will provide an easy means
for users to ensure that images and the documents that include these images are printed reliably.
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ISO 16760:2014(E)

This workflow relates to images that are destined for four-colour commercial printing. Photographers need
to be aware that alternative file versions of an image can still be required for specialized printing conditions.
Annex D provides further details of key RGB workflow concepts.
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INTERNATIONAL STANDARD ISO 16760:2014(E)
Graphic technology — Prepress data exchange —
Preparation and visualization of RGB images to be used in
RGB-based graphics arts workflows
1 Scope
This International Standard specifies requirements for an RGB workflow for graphic arts printing based on
the use of reflection prints (RGB Reference Prints) as the evaluation vehicle for coloured images. It provides
guidelines on the creation of print-targeted RGB images (RGB Reference Images) and simulation prints.
This International Standard requires the identification of a pair of ICC profiles for each image: an image
profile and a profile describing the reference printing system. These profiles provide individual colour
transformations for gamut mapping and colour separation. This International Standard does not provide
any guidance as to how these gamut mapping or colour separation transforms can be 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 3664:2009, Graphic technology and photography — Viewing conditions
ISO 11664-4 (CIE S 014-4/E:2007), Colorimetry — Part 4: CIE 1976 L*a*b* Colour space
ISO 12234-1, Electronic still-picture imaging — Removable memory — Part 1: Basic removable-memory model
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts images
ISO 15076-1:2010, Image technology colour management — Architecture, profile format and data
structure — Part 1: Based on ICC.1:2010
ISO 15790, Graphic technology and photography — Certified reference materials for reflection and
transmission metrology — Documentation and procedures for use, including determination of combined
standard uncertainty
1)
ISO 18619 , Image technology colour management — Black point compensation
2)
ISO 19445 , Graphic technology — Metadata for graphic arts workflow — XMP metadata for image and
document proofing
ISO/IEC 10918-1, Information technology — Digital compression and coding of continuous-tone still images:
Requirements and guidelines — Part 1
ISO/CIE 11664-6 (CIE S 014-6/E:2013), Colorimetry — Part 6: CIEDE2000 Colour-difference formula
TIFF, Revision 6.0 Final, Adobe Systems Incorporated, June 3, 1992
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
1) Under preparation.
2) Under preparation.
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ISO 16760:2014(E)

3.1
RGB colour space
three-component colour encoding defined by a linear transform from CIE XYZ
Note 1 to entry: Such a transform can be specified as a 3 × 3 matrix, and the transform between XYZ and additive
RGB is then performed by multiplying by this matrix or its inverse.
Note 2 to entry: Adobe RGB (1998) is an example of an RGB colour space.
3.2
characterized printing condition
printing condition for which process control aims are defined and for which the relationship between
input data (printing-tone values, usually CMYK) and the colorimetry of the printed image is documented
Note 1 to entry: The relationship between input data (printing tone values) and the colorimetry of the printed
image is commonly referred to as characterization.
Note 2 to entry: It is generally preferred that the process control aims of the printing condition and the associated
characterization data be made publicly available via the accredited standards process or industry trade
associations.
3.3
colour gamut
solid in a colour space, consisting of all those colours that are: present in a specific scene, artwork,
photograph, photomechanical, or other reproduction; or capable of being created using a particular
output device and/or medium
[SOURCE: ISO 22028-1:2004, 3.8]
3.4
colour rendering
mapping of image data representing the colour space coordinates of the elements of a scene to output-
referred image data representing the colour space coordinates of the elements of a reproduction
Note 1 to entry: Colour rendering generally consists of one or more of the following: compensating for differences
in the input and output viewing conditions, tone scale and colour gamut mapping to map the scene colours onto
the dynamic range and colour gamut of the reproduction, and applying preference adjustments.
Note 2 to entry: In the terminology defined in ISO 22028-1, some of the transforms described in this International
Standard would be better described as colour re-rendering, however, this International Standard does not differentiate
between colour rendering and colour re-rendering transforms and uses the term ‘colour rendering’ for both.
[SOURCE: ISO 22028-1:2004, 3.11]
3.5
highlight point
luminance level or image area corresponding to a reference white in the principal subject area of a scene
Note 1 to entry: Lightness of the objects in the scene are viewed in relation to this reference white. This can be a
white “object” such as a piece of paper, a shirt, etc. or some such object which does not even appear in the scene
but with which a comparison is made by reference to one’s memory of such objects.
Note 2 to entry: Image areas brighter than this point are called highlights. These include specular highlights,
diffuse highlights that are more highly illuminated than the principal area and fluorescent colours.
[22] [23]
Note 3 to entry: This wording is based on Bartleson and Breneman and Giorgianni and Madden .
3.6
output intent
metadata used to communicate the intended printing condition, usually by means of an ICC Profile
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ISO 16760:2014(E)

3.7
prepress
first stage of the graphic technology workflow, prior to printing, that includes all the operations
necessary for the preparation of images and image carriers
3.8
RGB Reference Image
RGB image prepared according to this specification which can provide a reliable reference to printed
appearance for evaluation by stakeholders
3.9
RGB Reference Print
print of an RGB Reference Image that has been prepared in conformance with this International Standard
3.10
RGB Reference Printer
printing system that is capable of producing RGB Reference Prints
Note 1 to entry: RGB Reference Printers do not use RGB inks but typically use CMYK inks, converting from RGB to
CMYK before printing.
3.11
shadow point
luminance level or image area corresponding to a maximum dark point and/or area of a scene that
should be reproduced as a dark end of grey gradient on a print or a display
4 RGB workflow overview
4.1 General
RGB images are represented in an RGB colour space such as sRGB or Adobe RGB (1998) and as part of
the prepress processing need to be converted to CMYK or similar colour space for printing. It is now
standard industry practice to convert to a characterized printing condition, for example, CGA/TS 21-
CRPC6, Fogra39, or JapanColor using ICC colour conversion.
NOTE The reference printing conditions that are provided as examples here are for offset lithography;
however, the principles of this International Standard apply to all standardised printing conditions.
This Clause describes how to make RGB Reference Images (4.2) and how to make simulation prints
(RGB Reference Prints) based on the characterized printing condition (4.3).
4.2 RGB Reference Images
4.2.1 Configuration of RGB workflow
Figure 3 shows image-processing workflow using RGB Reference Images. A process to convert
RGB images to RGB Reference Images shall be supported and a process to convert RGB Reference Images
to simulation print should be supported.
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ISO 16760:2014(E)

Monitor
Application software RGB RGB
RGB ICC colour
includingimage Reference Reference
image conversion
processing Image Print
GUI
Adjustgreybalance,
tone,highlight point,
shadowpoint,colour,
cropping, sharpness, e.t.c.
Figure 3 — Image processing workflow for creating RGB reference print
Components of this workflow comprise processing hardware, processing software, and image data files.
Processing hardware comprises a computer, a monitor, and a printer.
Processing software usually comprises operating system software of the computer and application
software. These software components shall support ICC profile-based colour management.
Image data files are of two types: “RGB image” which is an unprocessed input image data file (RGB
image in Figure 3) and the second ‘RGB Reference Image’ which is an output image data file prepared for
printing (RGB Reference Image in Figure 3). Both images shall be display-referred.
NOTE Examples of display-referred images include images encoded as sRGB and Adobe RGB (1998) (commonly
referred to as “Adobe RGB images” and “sRGB images”).
4.2.2 Setup and calibration
Setup and calibration of system hardware and software shall be performed prior to its use.
Monitors shall be calibrated and profiled using appropriate hardware and software. Each monitor
should have a gamut that can adequately represent the intended print condition(s).
NOTE 1 ISO 12646 and ISO 14861 provide a good reference to ensure that monitors are set up appropriately for
soft proofing.
NOTE 2 In some cases, software-based calibration can reduce the number of levels and so it is usually more
effective to use hardware calibration where the monitor’s physical controls and/or its internal lookup tables are
modified, perhaps in conjunction with the graphic card’s lookup tables.
Printers shall be calibrated and profiled using appropriate hardware and software to ensure that prints
produced meet the aims specified in Clause 6.
4.2.3 Operation procedure
Creation of RGB Reference Images shall be performed as follows.
a) Open input RGB image to be displayed using colour management of system software and
application software.
b) Adjust grey balance, highlight point, and shadow point using application software (tone-setup).
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ISO 16760:2014(E)

c) Adjust colour to make preferred reproduction.
d) Check print-simulation image on the monitor (optional when an RGB Reference Print is made).
e) Create an RGB Reference Print and view in standard conditions to check image result (optional but
highly recommended for inexperienced users).
f) Store RGB Reference Image (R’G’B’) and add output-intent tag as specified in 5.2 using application
software.
NOTE 1 At step a), the RGB image is likely to be display-referred.
NOTE 2 In some instances, legacy profiles might produce a sub-standard perceptual rendering and fail to
achieve an acceptable appearance match. Additional image editing might be required. Alternatively, a print
that achieves an appearance match to the original RGB image can be made using an ICC Profile that provides an
appearance match transform (for example, using CIECAM) in its Perceptual Rendering Intent.
4.2.4 Highlight and shadow point adjustment
The way in which the highlight point and shadow point is selected is beyond the scope of this document.
Users shall select desired highlight and shadow points for each image.
For an average-key image encoded in 8 bits, the desired highlight and shadow points of an RGB Reference
Image are approximately code values of 246 and 15 respectively. The relationship between these values
and tone reproduction of typical press printing profiles is shown in Annex A.
4.2.5 Additional data requirements
In order to provide colour rendering information, in particular the intended output rendering of the
RGB Reference Print and to enable automatic printing of the RGB Reference Print (Figure 6 — Case C),
the following rendering information and parameters shall be added to the image files:
a) colour characterization of source data;
b) rendering intent;
c) black point compensation;
d) output intent profile.
Colour characterization of source data shall be included in the form of an ICC Profile or colour space
name as specified for the appropriate file format.
Colour rendering parameters b) to d) are specified for each file format in the following clauses. The
parameters shall be included as specified in this clause as extensions to the file format as specified in
5.2 or as XMP metadata as specified in 5.3.
At the time of image preparation, these parameters s
...

INTERNATIONAL ISO
STANDARD 16760
First edition
2014-12-15

Graphic technology — Prepress data
exchange — Preparation and
visualization of RGB images to be used in
RGB-based graphics arts workflows
Technologie graphique — Échange de données pré-impression —
Préparation et visualisation d'images RGB à utiliser dans les flux de
travail des arts graphiques basés sur le RGB




Reference number
ISO 16760:2014(E)
©
ISO 2014

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ISO 16760:2014(E)


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COPYRIGHT PROTECTED DOCUMENT


©  ISO 2014
All rights reserved. Unless otherwise specified, 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
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 2014 – All rights reserved

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ISO 16760:2014(E)
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