SIST ISO 22028-4:2024

Photography and graphic technology — Extended colour encodings for digital image storage, manipulation and interchange — Part 4: European Colour Initiative RGB colour image encoding [eciRGB (2008)]

This document defines an extended colour-gamut output-referred RGB colour image encoding designated as European Colour Initiative RGB [eciRGB (2008)]. Digital images encoded using eciRGB (2008) can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging systems. Two precision levels are defined, using 8 bits/channel and 16 bits/channel.

Photographie et technologie graphique — Codages par couleurs étendues pour stockage, manipulation et échange d'image numérique — Partie 4: Codage d'image en couleurs RGB par initiative de couleur européenne [eciRGB(2008)]

Fotografija in grafična tehnologija - Razširjeno barvno kodiranje za shranjevanje, izmenjavo in ravnanje z digitalnimi slikami - 4. del: RGB po Evropski barvni pobudi za barvno kodiranje slik [eciRGB (2008)]

Ta dokument določa razširjeno kodiranje barvne slike z barvno lestvico RGB, imenovano evropska barvna pobuda RGB [eciRGB (2008)]. Digitalne slike, kodirane z eciRGB (2008), se lahko obdelujejo, shranjujejo, prenašajo, prikazujejo ali tiskajo z digitalnimi sistemi za slikanje nepremičnih slik. Opredeljeni sta dve stopnji natančnosti, in sicer z uporabo 8-bitov/kanal in 16-bitov/kanal.

General Information

• Status: Published
• Publication Date: 31-Jan-2024
• ICS: 01.070 - Colour coding
• ICS: 35.040.30 - Coding of graphical and photographical information
• ICS: 37.040.99 - Other standards related to photography
• ICS: 37.100.01 - Graphic technology in general
• Technical Committee: GRT - Graphical technology
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 24-Jan-2024
• Due Date: 30-Mar-2024
• Completion Date: 01-Feb-2024
• Ref Project: ISO 22028-4:2023 - Photography and graphic technology — Extended colour encodings for digital image storage, manipulation and interchange — Part 4: European Colour Initiative RGB colour image encoding [eciRGB (2008)]

Relations

• Replaces: SIST-TS ISO/TS 22028-4:2014 - Photography and graphic technology - Extended colour encodings for digital image storage, manipulation and interchange - Part 4: European Colour Initiative RGB colour image encoding [eciRGB (2008)]
• Effective Date: 01-Mar-2024

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2024
Nadomešča:
SIST-TS ISO/TS 22028-4:2014
Fotografija in grafična tehnologija - Razširjeno barvno kodiranje za shranjevanje,
izmenjavo in ravnanje z digitalnimi slikami - 4. del: RGB po Evropski barvni pobudi
za barvno kodiranje slik [eciRGB (2008)]
Photography and graphic technology — Extended colour encodings for digital image
storage, manipulation and interchange — Part 4: European Colour Initiative RGB colour
image encoding [eciRGB (2008)]
Photographie et technologie graphique — Codages par couleurs étendues pour
stockage, manipulation et échange d'image numérique — Partie 4: Codage d'image en
couleurs RGB par initiative de couleur européenne [eciRGB(2008)]
Ta slovenski standard je istoveten z: ISO 22028-4:2023
ICS:
01.070 Barvno kodiranje Colour coding
35.040.30 Kodiranje grafičnih in Coding of graphical and
fotografskih informacij photographical information
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.

INTERNATIONAL ISO
STANDARD 22028-4
First edition
2023-09
Photography and graphic
technology — Extended colour
encodings for digital image storage,
manipulation and interchange —
Part 4:
European Colour Initiative RGB colour
image encoding [eciRGB (2008)]
Photographie et technologie graphique — Codages par couleurs
étendues pour stockage, manipulation et échange d'image
numérique —
Partie 4: Codage d'image en couleurs RGB par initiative de couleur
européenne [eciRGB(2008)]
Reference number
© ISO 2023
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 4
4.1 General . 4
4.2 Reference viewing environment . 5
4.2.1 General . 5
4.2.2 Ambient illumination . 5
4.2.3 Reference display surround . 5
4.2.4 Image size and viewing distance . 5
4.2.5 Glare. 5
4.2.6 Measurements . 6
4.3 Reference display . 6
4.3.1 Contrast ratio . 6
4.3.2 Reference display white point and luminance . 6
4.3.3 Reference display black point and luminance . 6
4.4 eciRGB (2008) colour image encoding . 7
4.4.1 General . 7
4.4.2 Colour space chromaticities and luminance . 7
4.4.3 Colour space encodings . 7
4.4.4 Image state . 7
4.4.5 Normalized and absolute XYZ tristimulus values . 8
4.4.6 Encoding an image in 24-bit eciRGB (2008) colour image encoding . 8
4.4.7 Decoding 24-bit eciRGB (2008) to XYZ (D50) values . 9
Annex A (informative) The eciRGB (2008) ICC profile considerations .11
Annex B (informative) Practical tolerances for viewing eciRGB (2008) encoded images .12
Annex C (informative) Comparison of primaries .15
Bibliography .17
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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
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 42 Photography.
This first edition cancels and replaces the first edition (ISO/TS 22028-4:2012), which has been
technically revised.
The main changes are as follows:
— this document is released as an International Standard (prior edition was a Technical Specification);
— editorial revisions have been made.
A list of all parts in the ISO 22028 series can be found on the ISO website.
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
This document has been developed in order to meet the industry need for a complete, fully documented,
publicly available definition of an output-referred extended gamut RGB colour image encoding which is
optimized for an 8-bit encoding and the conversion of RGB images into offset print colour spaces. Since
users have also asked for a 16-bit encoding it has been added to this document as well. This colour image
encoding provides a way to represent output-referred images that does not limit the colour gamut to
those colours capable of being displayed on a CRT monitor, such as that represented by the sRGB colour
encoding, or require the use of negative RGB colorimetry coordinates, such as with extended sRGB
colour encodings like bg-sRGB.
An extended colour-gamut colour encoding is particularly desirable for professional photography
applications. For example, colours used for company logos may be outside a monitor gamut and would
therefore need to be clipped or compressed to a less saturated colour. Similarly, scanned photographic
prints that are to be duplicated may contain colours outside a monitor RGB colour-gamut. By using a
standard output-referred extended gamut colour image encoding, images containing such colours can
be stored, interchanged, manipulated, and later printed, without limiting or distorting the colours of
the final output.
The European Colour Initiative (ECI) RGB colour image encoding [eciRGB (2008)] specified in this
document meets the needs of these types of applications.
The primaries of eciRGB (2008) (see Annex C, Figures C.1 and C.2) are between Reference Output
Medium Metric RGB (ROMM RGB) and sRGB, thereby providing a larger gamut than sRGB, together with
lower quantization errors than ROMM RGB. The tone curve has an encoding linear to the L* axis defined
in the CIE 1976 (L*, a*, b*) colour space (CIELAB 1976).
This document has been prepared to provide sufficient documentation, consistent with the definitions
of ISO 22028-1, to allow the imaging community adequate opportunity for implementation and
evaluation of this colour image encoding. Sufficient implementation of, and practical experience in the
use of, eciRGB (2008), has led to a revision of the former Technical Specification and its conversion into
an International Standard.
The European Colour Initiative owns the copyright on the name eciRGB (2008) and has granted ISO the
irrevocable non-exclusive right to use the name for the purpose of this document. A colour encoding
named eciRGB was initiated by ECI in 2004. A second version of this encoding with a modified tonal
curve was defined in 2008. Because of its importance to the European photographers and graphic arts
industry, this document was prepared in order to fully define eciRGB according to ISO 22028-1.
v
INTERNATIONAL STANDARD ISO 22028-4:2023(E)
Photography and graphic technology — Extended colour
encodings for digital image storage, manipulation and
interchange —
Part 4:
European Colour Initiative RGB colour image encoding
[eciRGB (2008)]
1 Scope
This document defines an extended colour-gamut output-referred RGB colour image encoding
designated as European Colour Initiative RGB [eciRGB (2008)]. Digital images encoded using eciRGB
(2008) can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging
systems. Two precision levels are defined, using 8 bits/channel and 16 bits/channel.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
const
...

INTERNATIONAL ISO
STANDARD 22028-4
First edition
2023-09
Photography and graphic
technology — Extended colour
encodings for digital image storage,
manipulation and interchange —
Part 4:
European Colour Initiative RGB colour
image encoding [eciRGB (2008)]
Photographie et technologie graphique — Codages par couleurs
étendues pour stockage, manipulation et échange d'image
numérique —
Partie 4: Codage d'image en couleurs RGB par initiative de couleur
européenne [eciRGB(2008)]
Reference number
© ISO 2023
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 4
4.1 General . 4
4.2 Reference viewing environment . 5
4.2.1 General . 5
4.2.2 Ambient illumination . 5
4.2.3 Reference display surround . 5
4.2.4 Image size and viewing distance . 5
4.2.5 Glare. 5
4.2.6 Measurements . 6
4.3 Reference display . 6
4.3.1 Contrast ratio . 6
4.3.2 Reference display white point and luminance . 6
4.3.3 Reference display black point and luminance . 6
4.4 eciRGB (2008) colour image encoding . 7
4.4.1 General . 7
4.4.2 Colour space chromaticities and luminance . 7
4.4.3 Colour space encodings . 7
4.4.4 Image state . 7
4.4.5 Normalized and absolute XYZ tristimulus values . 8
4.4.6 Encoding an image in 24-bit eciRGB (2008) colour image encoding . 8
4.4.7 Decoding 24-bit eciRGB (2008) to XYZ (D50) values . 9
Annex A (informative) The eciRGB (2008) ICC profile considerations .11
Annex B (informative) Practical tolerances for viewing eciRGB (2008) encoded images .12
Annex C (informative) Comparison of primaries .15
Bibliography .17
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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
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 42 Photography.
This first edition cancels and replaces the first edition (ISO/TS 22028-4:2012), which has been
technically revised.
The main changes are as follows:
— this document is released as an International Standard (prior edition was a Technical Specification);
— editorial revisions have been made.
A list of all parts in the ISO 22028 series can be found on the ISO website.
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
This document has been developed in order to meet the industry need for a complete, fully documented,
publicly available definition of an output-referred extended gamut RGB colour image encoding which is
optimized for an 8-bit encoding and the conversion of RGB images into offset print colour spaces. Since
users have also asked for a 16-bit encoding it has been added to this document as well. This colour image
encoding provides a way to represent output-referred images that does not limit the colour gamut to
those colours capable of being displayed on a CRT monitor, such as that represented by the sRGB colour
encoding, or require the use of negative RGB colorimetry coordinates, such as with extended sRGB
colour encodings like bg-sRGB.
An extended colour-gamut colour encoding is particularly desirable for professional photography
applications. For example, colours used for company logos may be outside a monitor gamut and would
therefore need to be clipped or compressed to a less saturated colour. Similarly, scanned photographic
prints that are to be duplicated may contain colours outside a monitor RGB colour-gamut. By using a
standard output-referred extended gamut colour image encoding, images containing such colours can
be stored, interchanged, manipulated, and later printed, without limiting or distorting the colours of
the final output.
The European Colour Initiative (ECI) RGB colour image encoding [eciRGB (2008)] specified in this
document meets the needs of these types of applications.
The primaries of eciRGB (2008) (see Annex C, Figures C.1 and C.2) are between Reference Output
Medium Metric RGB (ROMM RGB) and sRGB, thereby providing a larger gamut than sRGB, together with
lower quantization errors than ROMM RGB. The tone curve has an encoding linear to the L* axis defined
in the CIE 1976 (L*, a*, b*) colour space (CIELAB 1976).
This document has been prepared to provide sufficient documentation, consistent with the definitions
of ISO 22028-1, to allow the imaging community adequate opportunity for implementation and
evaluation of this colour image encoding. Sufficient implementation of, and practical experience in the
use of, eciRGB (2008), has led to a revision of the former Technical Specification and its conversion into
an International Standard.
The European Colour Initiative owns the copyright on the name eciRGB (2008) and has granted ISO the
irrevocable non-exclusive right to use the name for the purpose of this document. A colour encoding
named eciRGB was initiated by ECI in 2004. A second version of this encoding with a modified tonal
curve was defined in 2008. Because of its importance to the European photographers and graphic arts
industry, this document was prepared in order to fully define eciRGB according to ISO 22028-1.
v
INTERNATIONAL STANDARD ISO 22028-4:2023(E)
Photography and graphic technology — Extended colour
encodings for digital image storage, manipulation and
interchange —
Part 4:
European Colour Initiative RGB colour image encoding
[eciRGB (2008)]
1 Scope
This document defines an extended colour-gamut output-referred RGB colour image encoding
designated as European Colour Initiative RGB [eciRGB (2008)]. Digital images encoded using eciRGB
(2008) can be manipulated, stored, transmitted, displayed, or printed by digital still picture imaging
systems. Two precision levels are defined, using 8 bits/channel and 16 bits/channel.
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 3664:2009, Graphic technology and photography — Viewing conditions
ISO/CIE 11664-1, Colorimetry — Part 1: CIE standard colorimetric observers
ISO 22028-1:2016, Photography and graphic technology — Extended colour encodings for digital image
storage, manipulation and interchange — Part 1: Architecture and requirements
CIE Publication 15, Colorimetry
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
adapted white
colour stimulus that an observer who is adapted to the viewing environment would judge to be
perfectly achromatic and to have a luminance factor of unity, i.e. absolute colorimetric coordinates that
an observer would consider to be a perfect white diffuser
Note 1 to entry: The adapted white can vary within a scene.
3.2
additive RGB colour space
colorimetric colour space having three colour primaries (generally red, green and blue) such that CIE
XYZ tristimul
...