ISO 15076-1:2010
(Main)Image technology colour management — Architecture, profile format and data structure — Part 1: Based on ICC.1:2010
Image technology colour management — Architecture, profile format and data structure — Part 1: Based on ICC.1:2010
ISO 15076-1:2010 specifies a colour profile format and describes the architecture within which it can operate. This architecture supports the exchange of information which specifies the intended colour image processing of digital data. The required reference colour spaces and the data structures (tags) are also specified.
Gestion de couleur en technologie d'image — Architecture, format de profil et structure de données — Partie 1: Fondé sur l'ICC.1:2010
Upodobitvena tehnologija; barvno upravljanje - Arhitektura, format profila in podatkovna struktura - 1. del: Utemeljeno na ICC.1:2010
Ta del ISO 15076 določa format barvnega profila in opisuje arhitekturo, v okviru katere se lahko uporablja. Ta arhitektura podpira izmenjavo informacij, ki določajo predvideno barvno slikovno procesiranje digitalnih podatkov. Določeni so tudi zahtevani referenčni barvni razmiki in podatkovne strukture (oznake).
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INTERNATIONAL ISO
STANDARD 15076-1
Second edition
2010-12-01
Image technology colour management —
Architecture, profile format and data
structure —
Part 1:
Based on ICC.1:2010
Gestion de couleur en technologie d'image — Architecture, format de
profil et structure de données —
Partie 1: Fondé sur l'ICC.1:2010
Reference number
ISO 15076-1:2010(E)
©
ISO 2010
---------------------- Page: 1 ----------------------
ISO 15076-1:2010(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing 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 2010 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 15076-1:2010(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms, definitions and abbreviated terms.2
3.1 Terms and definitions .2
3.2 Abbreviated terms.5
4 Basic number types .6
4.1 General .6
4.2 dateTimeNumber .6
4.3 float32Number .7
4.4 positionNumber.7
4.5 response16Number.7
4.6 s15Fixed16Number.7
4.7 u16Fixed16Number .8
4.8 u1Fixed15Number .8
4.9 u8Fixed8Number .8
4.10 uInt16Number .8
4.11 uInt32Number .8
4.12 uInt64Number .8
4.13 uInt8Number .8
4.14 XYZNumber .9
4.15 Seven-bit ASCII.9
5 Conformance .9
6 Profile connection space, rendering intents, and device encoding .9
6.1 General considerations.9
6.2 Rendering intents.10
6.3 Profile connection space.11
6.4 Converting between PCSXYZ and PCSLAB encodings .17
6.5 Device encoding.17
7 Profile requirements.18
7.1 General .18
7.2 Profile header.19
7.3 Tag table.24
7.4 Tag data.25
8 Required tags.25
8.1 General .25
8.2 Common requirements .25
8.3 Input profiles.26
8.4 Display profiles.27
8.5 Output profiles.28
8.6 DeviceLink profile.29
8.7 ColorSpace profile.29
8.8 Abstract profile .30
8.9 NamedColor profile .30
8.10 Precedence order of tag usage.30
9 Tag definitions .31
© ISO 2010 – All rights reserved iii
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ISO 15076-1:2010(E)
9.1 General. 31
9.2 Tag listing. 32
10 Tag type definitions. 45
10.1 General. 45
10.2 chromaticityType . 45
10.3 colorantOrderType. 46
10.4 colorantTableType. 46
10.5 curveType . 47
10.6 dataType . 48
10.7 dateTimeType. 48
10.8 lut16Type . 49
10.9 lut8Type . 52
10.10 lutAToBType. 54
10.11 lutBToAType. 57
10.12 measurementType . 60
10.13 multiLocalizedUnicodeType . 61
10.14 multiProcessElementsType. 62
10.15 namedColor2Type. 68
10.16 parametricCurveType. 69
10.17 profileSequenceDescType. 70
10.18 profileSequenceIdentifierType . 71
10.19 responseCurveSet16Type. 72
10.20 s15Fixed16ArrayType. 75
10.21 signatureType . 75
10.22 textType . 75
10.23 u16Fixed16ArrayType . 76
10.24 uInt16ArrayType. 76
10.25 uInt32ArrayType. 76
10.26 uInt64ArrayType. 77
10.27 uInt8ArrayType. 77
10.28 viewingConditionsType . 77
10.29 XYZType. 78
Annex A (informative) Data colour encodings and rendering intents . 79
Annex B (informative) Embedding profiles. 83
Annex C (informative) Relationship between ICC profiles and PostScript CSAs and CRDs . 87
Annex D (informative) Profile connection space . 89
Annex E (informative) Chromatic adaptation tag. 102
Annex F (normative) Profile computational models. 105
Annex G (informative) Tables of required tags and tag list . 107
Bibliography. 113
iv © ISO 2010 – All rights reserved
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ISO 15076-1:2010(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 15076-1 was prepared by the International Color Consortium, in cooperation with Technical Committees
ISO/TC 130 Graphic technology and ISO/TC 42 Photography, under the provisions of the Cooperative
Agreement between ISO/TC130 and the International Color Consortium dated 2003-07-11.
This second edition cancels and replaces the first edition (ISO 15076-1:2005), which has been technically
revised to incorporate changes made in the profile specification. These include the addition of the perceptual
intent reference medium colour gamut, new technology signatures, a floating-point device encoding range, a
colorimetric intent image state tag, and a profile sequence identifier tag. In addition, the mediaBlackPointTag
has been deleted and PCSXYZ is no longer limited to the PCS illuminant.
ISO 15076-1 is technically identical to ICC.1:2010, Image technology colour management — Architecture,
profile format, and data structure (Profile version 4.3.0.0).
ISO 15076 consists of the following parts, under the general title Image technology colour management —
Architecture, profile format and data structure:
⎯ Part 1: Based on ICC.1:2010
© ISO 2010 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 15076-1:2010(E)
Introduction
0.1 General
®
This part of ISO 15076 specifies the profile format defined by the International Color Consortium (ICC). The
intent of this format is to provide a cross-platform profile format for the creation and interpretation of colour
data. Such profiles can be used to translate between different colour encodings, and to transform colour data
created using one device into another device’s native colour encoding. The acceptance of this format by
application and operating system vendors allows end users to transparently move profiles, and images with
embedded profiles, between different systems. For example, this allows a printer manufacturer to create a
single profile for multiple applications and operating systems.
It is assumed that the reader of this part of ISO 15076 has a good understanding of colour science and
imaging, such as familiarity with CIE, ISO and IEC colour standards, general knowledge of device
measurement and characterization, and familiarity with at least one operating system level colour
management system.
0.2 International Color Consortium
The International Color Consortium was formed with the primary intent of developing and administering a
colour profile format standard, and for the registration of the associated tag signatures and descriptions. The
founding members of this consortium were Adobe Systems Inc., Agfa-Gevaert N.V., Apple Computer, Inc.,
Eastman Kodak Company, FOGRA (Honorary), Microsoft Corporation, Silicon Graphics, Inc., Sun
Microsystems, Inc., and Taligent, Inc. These companies committed to fully support the standard in their
operating systems, platforms and applications. The consortium has since been expanded and now has over
60 members.
The initial version of the standard developed by the ICC has undergone various revisions, and it was agreed
by the ICC that its revision 4.2 first be proposed as an International Standard. It is that revision which formed
the basis of first edition of this part of ISO 15076 (ISO 15076-1:2005). This second edition is based on ICC
revision 4.3, which is a minor ICC revision and is therefore fully backward compatible with 4.2. All the
technical specifications contained in the first edition (ISO 15076-1:2005) are also given in this second edition,
and new specifications exclusive to this second edition are clearly identified. Informative material has also
been updated and clarified. The ICC will continue to administer its own version of ICC.1:2010 and, if
enhancements are made, will be seriously considered for future revisions of this part of ISO 15076.
ISO/TC 130 will work to ensure that there are no significant differences between the ICC and ISO versions of
this part of ISO 15076.
The ICC web site (www.color.org) provides supplementary information relevant to this part of ISO 15076 and
additional resources for developers and users. It also provides information on how to become a member of
ICC.
0.3 Colour management architecture and profile connection space
The underlying architecture assumed in this part of ISO 15076 is based around a reference colour space that
is unambiguously defined. The colour specification method selected was that defined by CIE which is
internationally accepted. The CIE system enables a set of tristimulus values (CIEXYZ) to be specified for a
coloured stimulus. These tristimulus values enable a user to determine whether colours match in appearance
when viewed by a typical observer in a specific viewing environment. It follows that it is possible to define the
colour appearance of a sample by these tristimulus values (or some defined transformation of them) for a
specified state of viewer adaptation. The colour appearance is simply the appearance of the colour to a typical
human observer, as opposed to the physical characteristics of the colour stimulus, which is not fully specified
using tristimulus values.
vi © ISO 2010 – All rights reserved
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ISO 15076-1:2010(E)
Calculation of the CIEXYZ values for transmitting or reflecting media is achieved from the spectral sum-
product of the reflectance or transmittance of the sample, the relative spectral power distribution of the
illumination source used to view it and the spectral 'sensitivity' of the standard observer. However, as CIE
defines two standard observers, two measurement geometries (for reflecting media) and a large number of
standard illuminants, it is necessary to restrict these options in order to have a colour specification system that
is not ambiguous for a particular application. For this part of ISO 15076, the ICC has defined such a restriction,
based on ISO 13655, and the resultant colour spaces are known as PCSXYZ and PCSLAB. Furthermore, the
simple CIE system (whether CIEXYZ or the CIELAB values derived from them) does not accommodate the
effect of surrounding stimuli to the sample being measured (which can be different for various types of media)
or the illumination. Both of these affect appearance so the PCS values do not by themselves specify
appearance. To overcome this problem, the PCS is used in two different ways. The first accounts only for the
assumed state of chromatic adaptation of the viewer, and describes the colorimetry of actual originals and
their reproductions, chromatically adapted to the PCS adopted white chromaticity, through the colorimetric
rendering intents. The second, which describes the colorimetry of an image colour rendered to a standard
reference medium under a specified viewing condition, is employed for the perceptual rendering intent and
optionally for the saturation rendering intent. Thus, it can incorporate corrections for different states of viewer
adaptation and other desired rendering effects, as well as accommodating differences between actual colour
encoding and device dynamic ranges and colour gamuts, and those of the perceptual intent reference medium.
When required, the viewing conditions can be specified to allow colour appearance to be determined for the
colorimetric rendering intents.
So, in summary, the PCS is based on CIEXYZ (or CIELAB) determined for a specific observer (CIE Standard
1931 Colorimetric Observer, often known colloquially as the 2 degree observer), relative to a specific
illuminant chromaticity (that of CIE D50), and measured with a specified measurement geometry (0°:45° or
45°:0°), for reflecting media. Measurement procedures are also defined for transmitting and self-luminous
media. Since the conversion from CIEXYZ to CIELAB is quite unambiguous, profile builders can use either
colour space for the PCS; the colour management system is able to determine which has been used from a
tag in the header.
For colorimetric renderings where the measured data were not obtained relative to a D50 adopted white
chromaticity, the profile builder is expected to adapt the data to achieve this. Therefore, a mechanism for
identifying the chromatic adaptation used in such situations is provided. For the perceptual rendering intent
the viewing conditions and reference medium are specified in order to provide a clear target for colour
rendering and re-rendering (including gamut mapping). In the following paragraphs, the reference colour
space, to which reference is made, needs to include the viewing conditions and reference medium when the
perceptual intent is being considered. For the perceptual rendering intent, profile builders are expected to
undertake any corrections for appearance effects if the viewing conditions used for monitors and transmitting
media (such as dark surrounds) differ from those typical for reflecting media, and to account for differences
between actual media and the reference medium.
Figure 1 shows how a reference colour space can be used to provide the common interface for
transformations between different colour encodings, as used by different devices, or even different operational
modes of the same device. Without it, a separate transformation would be required for each pair of device
modes. If there are n device modes to be supported in a system, and it is necessary to provide a
2
transformation between each pair of device modes, n transforms would need to be defined and n new
transforms would need to be defined every time a new device mode was added. As a new printer device
mode can consist simply of a new paper type, this is not a practical solution. By using a reference colour
space, only n transforms need be defined and only one new transform needs to be defined each time a new
device mode is added; whatever device-to-device transforms are needed can be constructed by linking the
source and destination profiles using the reference colour space as the interface.
© ISO 2010 – All rights reserved vii
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ISO 15076-1:2010(E)
RGB
printer
LCD
monitor
Digital
camera
T
T
T
Reference Printing
T
colour space
press
T
T
T
Scanner CMYK
printer
CRT
monitor
Key
T colour management transform
Figure 1 — Use of a reference colour space
While images can be encoded directly in PCSXYZ or PCSLAB, this will not generally be the case. A number
of colour encodings for open exchange have been standardized to meet a variety of needs. Depending on the
use case, different bit depths, image states, reference media and colour gamuts are needed. Devices also
have different characteristics resulting in different native encodings. Except for a few cases where default
encodings for key system devices are used for exchange (like the sRGB encoding), it is not practical or
productive to attempt to restrict system colour encoding support.
For reasons of precision, it is usually desirable to define the transformation between the colour data encoding
and the profile connection space (PCS) at a high precision. If the transformation between a colour data
encoding and the PCS is provided with an image file, it can be utilized when images are reproduced. In order
that the transformation between the colour data encoding and the PCS can be interpreted by all applications it
is important that it be defined in an open specification. The profile format defined in this part of ISO 15076
provides that specification.
0.4 Rendering intents
In general, actual device colour gamuts will fail to match each other, and that of the perceptual intent
reference medium, to varying degrees. Because of this mismatch, and because of the needs of different
applications, four rendering intents (colour rendering styles) are defined in this part of ISO 15076. Each one
represents a different colour reproduction objective. The colorimetric rendering intents operate directly on
viii © ISO 2010 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 15076-1:2010(E)
measured colorimetric values, with correction for chromatic adaptation when the measured values were not
obtained relative to the PCS adopted white chromaticity. The other rendering intents (perceptual and
saturation) operate on colorimetric values which are adjusted in an as-needed fashion to account for any
differences between devices, media, and viewing conditions.
Two colorimetric rendering intents are specified in this part of ISO 15076, though only one is included fully
constructed in the profile. The included media relative colorimetric intent is based on media-relative
colorimetry, which is normalized relative to the unprinted media white for reflecting, transmitting, and self
luminous media, or, in the case of colour encodings and capture, to the colour encoding values that
correspond to the highest perceived brightness. Thus the media white will have the values of 100, 0, 0 in
PCSLAB. This ensures that highlight clipping will not occur when the media-relative colorimetric intent is used.
...
SLOVENSKI STANDARD
SIST ISO 15076-1:2011
01-julij-2011
Upodobitvena tehnologija; barvno upravljanje - Arhitektura, format profila in
podatkovna struktura - 1. del: Utemeljeno na ICC.1:2010
Image technology colour management - Architecture, profile format and data structure -
Part 1: Based on ICC.1:2010
Gestion de couleur en technologie d'image - Architecture, format de profil et structure de
données - Partie 1: Fondé sur l'ICC.1:2010
Ta slovenski standard je istoveten z: ISO 15076-1:2010
ICS:
01.070 Barvno kodiranje Colour coding
37.100.99 'UXJLVWDQGDUGLY]YH]L] Other standards related to
JUDILþQRWHKQRORJLMR graphic technology
SIST ISO 15076-1:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 15076-1:2011
---------------------- Page: 2 ----------------------
SIST ISO 15076-1:2011
INTERNATIONAL ISO
STANDARD 15076-1
Second edition
2010-12-01
Image technology colour management —
Architecture, profile format and data
structure —
Part 1:
Based on ICC.1:2010
Gestion de couleur en technologie d'image — Architecture, format de
profil et structure de données —
Partie 1: Fondé sur l'ICC.1:2010
Reference number
ISO 15076-1:2010(E)
©
ISO 2010
---------------------- Page: 3 ----------------------
SIST ISO 15076-1:2011
ISO 15076-1:2010(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing 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 2010 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 15076-1:2011
ISO 15076-1:2010(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms, definitions and abbreviated terms.2
3.1 Terms and definitions .2
3.2 Abbreviated terms.5
4 Basic number types .6
4.1 General .6
4.2 dateTimeNumber .6
4.3 float32Number .7
4.4 positionNumber.7
4.5 response16Number.7
4.6 s15Fixed16Number.7
4.7 u16Fixed16Number .8
4.8 u1Fixed15Number .8
4.9 u8Fixed8Number .8
4.10 uInt16Number .8
4.11 uInt32Number .8
4.12 uInt64Number .8
4.13 uInt8Number .8
4.14 XYZNumber .9
4.15 Seven-bit ASCII.9
5 Conformance .9
6 Profile connection space, rendering intents, and device encoding .9
6.1 General considerations.9
6.2 Rendering intents.10
6.3 Profile connection space.11
6.4 Converting between PCSXYZ and PCSLAB encodings .17
6.5 Device encoding.17
7 Profile requirements.18
7.1 General .18
7.2 Profile header.19
7.3 Tag table.24
7.4 Tag data.25
8 Required tags.25
8.1 General .25
8.2 Common requirements .25
8.3 Input profiles.26
8.4 Display profiles.27
8.5 Output profiles.28
8.6 DeviceLink profile.29
8.7 ColorSpace profile.29
8.8 Abstract profile .30
8.9 NamedColor profile .30
8.10 Precedence order of tag usage.30
9 Tag definitions .31
© ISO 2010 – All rights reserved iii
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SIST ISO 15076-1:2011
ISO 15076-1:2010(E)
9.1 General. 31
9.2 Tag listing. 32
10 Tag type definitions. 45
10.1 General. 45
10.2 chromaticityType . 45
10.3 colorantOrderType. 46
10.4 colorantTableType. 46
10.5 curveType . 47
10.6 dataType . 48
10.7 dateTimeType. 48
10.8 lut16Type . 49
10.9 lut8Type . 52
10.10 lutAToBType. 54
10.11 lutBToAType. 57
10.12 measurementType . 60
10.13 multiLocalizedUnicodeType . 61
10.14 multiProcessElementsType. 62
10.15 namedColor2Type. 68
10.16 parametricCurveType. 69
10.17 profileSequenceDescType. 70
10.18 profileSequenceIdentifierType . 71
10.19 responseCurveSet16Type. 72
10.20 s15Fixed16ArrayType. 75
10.21 signatureType . 75
10.22 textType . 75
10.23 u16Fixed16ArrayType . 76
10.24 uInt16ArrayType. 76
10.25 uInt32ArrayType. 76
10.26 uInt64ArrayType. 77
10.27 uInt8ArrayType. 77
10.28 viewingConditionsType . 77
10.29 XYZType. 78
Annex A (informative) Data colour encodings and rendering intents . 79
Annex B (informative) Embedding profiles. 83
Annex C (informative) Relationship between ICC profiles and PostScript CSAs and CRDs . 87
Annex D (informative) Profile connection space . 89
Annex E (informative) Chromatic adaptation tag. 102
Annex F (normative) Profile computational models. 105
Annex G (informative) Tables of required tags and tag list . 107
Bibliography. 113
iv © ISO 2010 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 15076-1:2011
ISO 15076-1:2010(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 15076-1 was prepared by the International Color Consortium, in cooperation with Technical Committees
ISO/TC 130 Graphic technology and ISO/TC 42 Photography, under the provisions of the Cooperative
Agreement between ISO/TC130 and the International Color Consortium dated 2003-07-11.
This second edition cancels and replaces the first edition (ISO 15076-1:2005), which has been technically
revised to incorporate changes made in the profile specification. These include the addition of the perceptual
intent reference medium colour gamut, new technology signatures, a floating-point device encoding range, a
colorimetric intent image state tag, and a profile sequence identifier tag. In addition, the mediaBlackPointTag
has been deleted and PCSXYZ is no longer limited to the PCS illuminant.
ISO 15076-1 is technically identical to ICC.1:2010, Image technology colour management — Architecture,
profile format, and data structure (Profile version 4.3.0.0).
ISO 15076 consists of the following parts, under the general title Image technology colour management —
Architecture, profile format and data structure:
⎯ Part 1: Based on ICC.1:2010
© ISO 2010 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 15076-1:2011
ISO 15076-1:2010(E)
Introduction
0.1 General
®
This part of ISO 15076 specifies the profile format defined by the International Color Consortium (ICC). The
intent of this format is to provide a cross-platform profile format for the creation and interpretation of colour
data. Such profiles can be used to translate between different colour encodings, and to transform colour data
created using one device into another device’s native colour encoding. The acceptance of this format by
application and operating system vendors allows end users to transparently move profiles, and images with
embedded profiles, between different systems. For example, this allows a printer manufacturer to create a
single profile for multiple applications and operating systems.
It is assumed that the reader of this part of ISO 15076 has a good understanding of colour science and
imaging, such as familiarity with CIE, ISO and IEC colour standards, general knowledge of device
measurement and characterization, and familiarity with at least one operating system level colour
management system.
0.2 International Color Consortium
The International Color Consortium was formed with the primary intent of developing and administering a
colour profile format standard, and for the registration of the associated tag signatures and descriptions. The
founding members of this consortium were Adobe Systems Inc., Agfa-Gevaert N.V., Apple Computer, Inc.,
Eastman Kodak Company, FOGRA (Honorary), Microsoft Corporation, Silicon Graphics, Inc., Sun
Microsystems, Inc., and Taligent, Inc. These companies committed to fully support the standard in their
operating systems, platforms and applications. The consortium has since been expanded and now has over
60 members.
The initial version of the standard developed by the ICC has undergone various revisions, and it was agreed
by the ICC that its revision 4.2 first be proposed as an International Standard. It is that revision which formed
the basis of first edition of this part of ISO 15076 (ISO 15076-1:2005). This second edition is based on ICC
revision 4.3, which is a minor ICC revision and is therefore fully backward compatible with 4.2. All the
technical specifications contained in the first edition (ISO 15076-1:2005) are also given in this second edition,
and new specifications exclusive to this second edition are clearly identified. Informative material has also
been updated and clarified. The ICC will continue to administer its own version of ICC.1:2010 and, if
enhancements are made, will be seriously considered for future revisions of this part of ISO 15076.
ISO/TC 130 will work to ensure that there are no significant differences between the ICC and ISO versions of
this part of ISO 15076.
The ICC web site (www.color.org) provides supplementary information relevant to this part of ISO 15076 and
additional resources for developers and users. It also provides information on how to become a member of
ICC.
0.3 Colour management architecture and profile connection space
The underlying architecture assumed in this part of ISO 15076 is based around a reference colour space that
is unambiguously defined. The colour specification method selected was that defined by CIE which is
internationally accepted. The CIE system enables a set of tristimulus values (CIEXYZ) to be specified for a
coloured stimulus. These tristimulus values enable a user to determine whether colours match in appearance
when viewed by a typical observer in a specific viewing environment. It follows that it is possible to define the
colour appearance of a sample by these tristimulus values (or some defined transformation of them) for a
specified state of viewer adaptation. The colour appearance is simply the appearance of the colour to a typical
human observer, as opposed to the physical characteristics of the colour stimulus, which is not fully specified
using tristimulus values.
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SIST ISO 15076-1:2011
ISO 15076-1:2010(E)
Calculation of the CIEXYZ values for transmitting or reflecting media is achieved from the spectral sum-
product of the reflectance or transmittance of the sample, the relative spectral power distribution of the
illumination source used to view it and the spectral 'sensitivity' of the standard observer. However, as CIE
defines two standard observers, two measurement geometries (for reflecting media) and a large number of
standard illuminants, it is necessary to restrict these options in order to have a colour specification system that
is not ambiguous for a particular application. For this part of ISO 15076, the ICC has defined such a restriction,
based on ISO 13655, and the resultant colour spaces are known as PCSXYZ and PCSLAB. Furthermore, the
simple CIE system (whether CIEXYZ or the CIELAB values derived from them) does not accommodate the
effect of surrounding stimuli to the sample being measured (which can be different for various types of media)
or the illumination. Both of these affect appearance so the PCS values do not by themselves specify
appearance. To overcome this problem, the PCS is used in two different ways. The first accounts only for the
assumed state of chromatic adaptation of the viewer, and describes the colorimetry of actual originals and
their reproductions, chromatically adapted to the PCS adopted white chromaticity, through the colorimetric
rendering intents. The second, which describes the colorimetry of an image colour rendered to a standard
reference medium under a specified viewing condition, is employed for the perceptual rendering intent and
optionally for the saturation rendering intent. Thus, it can incorporate corrections for different states of viewer
adaptation and other desired rendering effects, as well as accommodating differences between actual colour
encoding and device dynamic ranges and colour gamuts, and those of the perceptual intent reference medium.
When required, the viewing conditions can be specified to allow colour appearance to be determined for the
colorimetric rendering intents.
So, in summary, the PCS is based on CIEXYZ (or CIELAB) determined for a specific observer (CIE Standard
1931 Colorimetric Observer, often known colloquially as the 2 degree observer), relative to a specific
illuminant chromaticity (that of CIE D50), and measured with a specified measurement geometry (0°:45° or
45°:0°), for reflecting media. Measurement procedures are also defined for transmitting and self-luminous
media. Since the conversion from CIEXYZ to CIELAB is quite unambiguous, profile builders can use either
colour space for the PCS; the colour management system is able to determine which has been used from a
tag in the header.
For colorimetric renderings where the measured data were not obtained relative to a D50 adopted white
chromaticity, the profile builder is expected to adapt the data to achieve this. Therefore, a mechanism for
identifying the chromatic adaptation used in such situations is provided. For the perceptual rendering intent
the viewing conditions and reference medium are specified in order to provide a clear target for colour
rendering and re-rendering (including gamut mapping). In the following paragraphs, the reference colour
space, to which reference is made, needs to include the viewing conditions and reference medium when the
perceptual intent is being considered. For the perceptual rendering intent, profile builders are expected to
undertake any corrections for appearance effects if the viewing conditions used for monitors and transmitting
media (such as dark surrounds) differ from those typical for reflecting media, and to account for differences
between actual media and the reference medium.
Figure 1 shows how a reference colour space can be used to provide the common interface for
transformations between different colour encodings, as used by different devices, or even different operational
modes of the same device. Without it, a separate transformation would be required for each pair of device
modes. If there are n device modes to be supported in a system, and it is necessary to provide a
2
transformation between each pair of device modes, n transforms would need to be defined and n new
transforms would need to be defined every time a new device mode was added. As a new printer device
mode can consist simply of a new paper type, this is not a practical solution. By using a reference colour
space, only n transforms need be defined and only one new transform needs to be defined each time a new
device mode is added; whatever device-to-device transforms are needed can be constructed by linking the
source and destination profiles using the reference colour space as the interface.
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SIST ISO 15076-1:2011
ISO 15076-1:2010(E)
RGB
printer
LCD
monitor
Digital
camera
T
T
T
Reference Printing
T
colour space
press
T
T
T
Scanner CMYK
printer
CRT
monitor
Key
T colour management transform
Figure 1 — Use of a reference colour space
While images can be encoded directly in PCSXYZ or PCSLAB, this will not generally be the case. A number
of colour encodings for open exchange have been standardized to meet a variety of needs. Depending on the
use case, different bit depths, image states, reference media and colour gamuts are needed. Devices also
have different characteristics resulting in different native encodings. Except for a few cases where default
encodings for key system devices are used for exchange (like the sRGB encoding), it is not practical or
productive to attempt to restrict system colour encoding support.
For reasons of precision, it is usually desirable to define the transformation between the colour data encoding
and the profile connection space (PCS) at a high precision. If the transformation between a colour data
encoding and the PCS is provided with an image file, it can be utilized when images are reproduced. In order
that the transformation between the colour data encoding and the PCS can be interpreted by all applications it
is important that it be defined in an open specification. The profile format defined in this part of ISO 15076
provides that specification.
0.4 Rendering intents
In general, actual device colour gamuts will fail to match each other, and that of the perceptual intent
reference medium, to varying degrees. Because of this mismatch, and because of the needs of different
applications, four rendering intents (colour rendering styles) are defined in this part of ISO 15076. Each one
represents a different colour reproduction objective. The colorimetric rendering intents operate directly on
viii © ISO 2010 – All rights r
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