IEC 61966-12-1:2020
(Main)Multimedia systems and equipment - Colour measurement and management - Part 12-1: Metadata for identification of colour gamut (Gamut ID)
Multimedia systems and equipment - Colour measurement and management - Part 12-1: Metadata for identification of colour gamut (Gamut ID)
IEC 61966-12-1:2020 defines the colour gamut metadata scheme for video systems and similar applications. The metadata can be associated with wide-gamut video colour content or to a piece of equipment to display the content. When associated with content, the colour gamut metadata defines the gamut for which the content was created. It can be used by the display for controlled colour reproduction even if the display’s colour gamut is different from that of the content. When associated with a display, the colour gamut metadata defines the display colour gamut. It can be used during content creation to enable improved colour reproduction. The colour gamut metadata can cover associated colour encoding information, which includes all information required for a controlled colour reproduction, when such information is not provided by the colour encoding specification. The colour gamut metadata scheme provides scalable solutions. For example, more flexible solutions will be used for the professional use, while much simpler solutions will be used for consumer use with easier product implementation. This part of IEC 61966 only defines the colour gamut metadata scheme. Vendor-specific solutions for creation and end-use of this metadata are allowed. IEC 61966-12-1:2020 cancels and replaces the first edition published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) ITU-R BT.2020 colour spaces added in Clause 6;
b) ITU-R BT.2100 colour spaces added in Clause 6.
Systèmes et appareils multimédias - Mesure et gestion de la couleur - Partie 12-1: Métadonnées d'identification des gammes de couleurs (Gamut ID)
L'IEC 61966-12-1:2020 définit l'agencement des métadonnées des gammes de couleurs destiné aux systèmes vidéo et applications similaires. Les métadonnées peuvent être associées à un contenu vidéo à gamme de couleurs étendue ou à un appareil qui sert à afficher ce contenu. Lorsqu'elles sont associées au contenu, les métadonnées de gamme de couleurs définissent la gamme de couleurs pour laquelle le contenu a été créé. Elles peuvent être utilisées par l'écran pour piloter la reproduction des couleurs, même si la gamme de couleurs de l'écran est différente de celle du contenu. Lorsqu'elles sont associées à un écran, les métadonnées de gamme de couleurs définissent la gamme des couleurs de l'écran. Elles peuvent servir pendant la création du contenu, pour permettre une meilleure reproduction des couleurs. Les métadonnées de gammes de couleurs peuvent intégrer des informations associées de codage des couleurs, dont toutes celles nécessaires à une reproduction contrôlée des couleurs, lorsque ces informations ne sont pas fournies par la spécification du codage des couleurs. L'agencement des métadonnées des gammes de couleurs apporte des solutions évolutives. Par exemple, des solutions plus souples servent à un usage professionnel, alors que des solutions beaucoup plus simples servent au grand public, avec une mise en œuvre plus facile du produit. La présente partie de l'IEC 61966 ne définit que l'agencement des métadonnées des gammes de couleurs. Des solutions spécifiques à un fournisseur, pour la création et l'usage final de ces métadonnées, sont admises. L'IEC 61966-12-1:2020 annule et remplace la première édition parue en 2011. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout des espaces de couleurs UIT-R BT.2020 à l'Article 6;
b) ajout des espaces de couleurs UIT-R BT.2100 à l'Article 6.
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IEC 61966-12-1 ®
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STANDARD
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Multimedia systems and equipment – Colour measurement and management –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
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IEC 61966-12-1 ®
Edition 2.0 2020-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Multimedia systems and equipment – Colour measurement and management –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.180.20; 33.160.40 ISBN 978-2-8322-8905-1
– 2 – IEC 61966-12-1:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 4
INTRODUCTION . 2
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 8
4 Overview . 9
5 Header of Gamut ID metadata . 9
6 Description of gamut geometry (full profile) . 13
6.1 General . 13
6.2 Gamut geometry . 13
6.3 Header of description of gamut geometry . 14
6.4 Gamut Instances . 16
6.5 Gamut Hulls . 18
6.6 Gamut Component . 19
6.6.1 General . 19
6.6.2 Packing of face indices . 20
6.7 Faces. 21
6.7.1 General . 21
6.7.2 Packing of vertex indices . 22
6.8 Vertices . 22
6.8.1 General . 22
6.8.2 Packing of colour space coordinates for vertices . 23
7 Description of gamut geometry (medium and simple profiles) . 24
7.1 General . 24
7.2 Medium profile . 24
7.3 Simple profile . 24
8 Description of colour reproduction . 25
Annex A (informative) Size of Gamut ID metadata . 28
Annex B (informative) Motivation and requirements . 29
B.1 History . 29
B.2 Motivation . 29
B.3 Scope of Gamut ID metadata . 30
B.4 Requirements . 30
B.5 Structure . 31
B.6 Specific features . 33
Annex C (informative) Use of profiles . 35
C.1 Gamut ID profiles . 35
C.2 Medium profile . 35
C.3 Simple profile . 36
Annex D (informative) Example of Gamut ID metadata in simple profile . 37
Bibliography . 41
Figure 1 – Logical structure of the description of gamut geometry (full profile) . 13
Figure B.1 – Scope of Gamut ID – Generation and use of metadata are not specified . 30
Figure B.2 – Example of a description of gamut geometry in CIEXYZ colour space
consisting of a set of triangular faces . 31
Figure B.3 – Example of a gamut with identified ridge due to colorant channels . 34
Figure B.4 – Example of a non-convex gamut with two convex Gamut Hulls. 34
Table 1 – Format of Gamut ID metadata . 9
Table 2 – Header of Gamut ID metadata . 10
Table 3 – Bit depth for encoding of a colour space coordinate . 12
Table 4 – Description of gamut geometry . 14
Table 5 – Header of description of gamut geometry . 15
Table 6 – Gamut Instances . 16
Table 7 – ith Gamut Instance . 17
Table 8 – Gamut Hulls . 18
Table 9 – hth Gamut Hull . 19
Table 10 – Definition of Gamut Components . 20
Table 11 – cth Gamut Component . 20
Table 12 – Example for packing of Gamut Components . 21
Table 13 – Definition of faces . 21
Table 14 – Example for packing of faces . 22
Table 15 – Vertices . 23
Table 16 – Packing of 10-bit colour space coordinates . 23
Table 17 – Packing of 12-bit colour space coordinates . 24
Table 18 – Description of gamut geometry (simple profile) . 25
Table 19 – Header of description of gamut geometry (simple profile) . 25
Table 20 – Definition of vertices (simple profile) . 25
Table 21 – Header of description of colour reproduction . 26
Table B.1 – Requirements and Gamut ID features . 33
Table C.1 – Profiles for the description of gamut geometry . 35
Table D.1 – Colour gamut for digital cinema . 37
Table D.2 – Example for the header . 37
Table D.3 – Example for the header of description of gamut geometry . 38
Table D.4 – Example of definition of vertices . 38
Table D.5 – Encoded colour space coordinates for vertices . 38
– 4 – IEC 61966-12-1:2020 RLV © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTIMEDIA SYSTEMS AND EQUIPMENT –
COLOUR MEASUREMENT AND MANAGEMENT –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
FOREWORD
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This redline version of the official IEC Standard allows the user to identify the changes
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International Standard IEC 61966-12-1 has been prepared by technical area 2: Colour
measurement and management, of IEC technical committee 100: Audio, video and multimedia
systems and equipment.
This second edition cancels and replaces the first edition published in 2011. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) ITU-R BT.2020 colour spaces added in Clause 6;
b) ITU-R BT.2100 colour spaces added in Clause 6.
The text of this International Standard is based on the following documents:
CDV Report on voting
100/3126/CDV 100/3375/RVC
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61966 series, published under the general title Multimedia systems
and equipment – colour measurement and management, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
– 6 – IEC 61966-12-1:2020 RLV © IEC 2020
INTRODUCTION
New technologies in capturing and displaying wide-gamut colour images enable a new market
of wide-gamut video colour content and high dynamic range video content creation. Recent
video standards for wide gamut colour space encoding such as ITU-R BT.2020 (UHDTV) and
IEC 61966-2-4 (xvYCC) were established in order to be able to distribute content with a colour
gamut that is extended with respect to classical colour gamuts such as defined by colorimetry
standards ITU-R BT.601 (standard-definition television) and ITU-R BT.709 (high-definition
television). Recent video standards for high dynamic range (HDR) colour space encoding, such
as ITU-R BT.2100, were established in order to be able to distribute content with a colour gamut
and a dynamic range that are both extended with respect to classical colour encoding, such as
that defined by ITU-R BT.709. With the increasing popularity of wide gamut and high dynamic
range content and displays, the variety of colour gamuts of displays is expected to increase.
This issue can be an obstacle for adopting wide-gamut video colour content in professional
content creation since the compatibility of the content to the employed displays as well as the
compatibility among different displays is not ensured. The term display includes here any video
colour reproduction equipment, such as direct view displays and projectors. Thanks to
improvements of technology, the variety of colour gamut and colour reproduction capacities of
displays increases, while the colour gamut and the colour encoding rules of existing colour
space encoding standards are fixed.
To address this issue, the IEC standard Gamut ID (IEC 61966-12-1) this document specifies a
colour gamut metadata scheme for video systems including information for colour reproduction.
This metadata can amend a video content or a display. More specifically, improvements can be
achieved if the wide-gamut colour content is created with the knowledge of the display colour
gamut as well as if the colour reproduction in the display is done with the knowledge of the
colour gamut of the pictorial content.
This standard enables video systems defining This document permits video systems to define
their own colour gamut. This document defines necessary metadata that allows managing
inhomogeneous video systems with different colour gamuts. This document generalizes existing
colour space encoding standards having a fixed colour gamut.
MULTIMEDIA SYSTEMS AND EQUIPMENT –
COLOUR MEASUREMENT AND MANAGEMENT –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
1 Scope
This part of IEC 61966 defines the colour gamut metadata scheme for video systems and similar
applications.
The metadata can be associated with wide-gamut video colour content or to a piece of
equipment to display the content.
When associated with content, the colour gamut metadata defines the gamut for which the
content was created. It can be used by the display for controlled colour reproduction even if the
display’s colour gamut is different from that of the content.
When associated with a display, the colour gamut metadata defines the display colour gamut.
It can be used during content creation to enable improved colour reproduction.
The colour gamut metadata may can cover associated colour encoding information, which
includes all information required for a controlled colour reproduction, when such information is
not provided by the colour encoding specification.
The colour gamut metadata scheme provides scalable solutions. For example, more flexible
solutions will be used for the professional use, while much simpler solutions will be used for
consumer use with easier product implementation.
This part of IEC 61966 only defines the colour gamut metadata scheme. Vendor-specific
solutions for creation and end-use of this metadata are allowed.
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.
IEC 60050-845:1987, International electrochnical vocabulary – Chapter 845: Lighting
IEC 61966-2-4:2006, Multimedia systems and equipment – Colour measurement and
management – Part 2-4: Colour management – Extended-gamut YCC colour space for video
applications – xvYCC
ISO 15076-1:20052010, Image technology colour management – Architecture, profile format
and data structure – Part 1: Based on ICC.1:2004-102010
ISO 22028-1:2004, Photography and graphic technology – Extended colour encodings for
digital image storage, manipulation and interchange – Part 1: Architecture and requirements
ITU-R BT.709-5:2002, Parameter values for the HDTV standards for production and
international programme exchange
– 8 – IEC 61966-12-1:2020 RLV © IEC 2020
CIE 15:2004, Colorimetry
SMPTE 274M:2005, SMPTE Standard for Television - 1920 x 1080 Image Sample Structure,
Digital Representation and Digital Timing Reference Sequences for Multiple Picture Rates
ITU-R BT.2020, Parameter values for ultra-high definition television systems for production and
international programme exchange
ITU-R BT.2100, Image parameter values for high dynamic range television for use in production
and international programme exchange
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions as well as the terms and
definitions of colour space, illuminance, luminance, tristimulus, and other related lighting terms
of IEC 60050(845) apply.
For the purposes of this document, the terms and definitions given in IEC 60050-845 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
content
video content in production, post-production or consumption
3.1.2
gamut
solid in a colour space
Note 1 to entry: A solid in a colour space, such as specified by ITU-R BT.2100, can contain colours with high
luminance.
3.1.3
gamut boundary description
description of the boundary of a colour gamut
3.1.4
radiometrically-linear colour space coordinates
colour space coordinates that are linear with respect to image radiance
3.2 Abbreviated terms
GBD gamut boundary description
LSB least significant bit
MSB most significant bit
GI gamut instance
GH gamut hull
GC gamut component
4 Overview
This document specifies metadata called "Gamut ID metadata" providing information on an
actual colour gamut.
The Gamut ID metadata contains four parts and its format is summarized in Table 1.
Table 1 – Format of Gamut ID metadata
Byte # Metadata content
hex
0h0000 Header of Gamut ID metadata
ID_G Description of gamut geometry
ID_E Description of colour reproduction
Clause 5 specifies the header of Gamut ID metadata.
Clauses 6 and 7 specify the description of gamut geometry that corresponds to one of three
profiles as listed below:
• full profile;
• medium profile;
• simple profile.
Clause 6 specifies the full profile of the description of gamut geometry. The medium and simple
profiles are specified in Clause 7.
Clause 8 specifies the description of colour reproduction.
Annex A discusses the size of Gamut ID metadata.
Annex B gives background information.
Annex C discusses the use of simple, medium and full profiles.
5 Header of Gamut ID metadata
The Gamut ID metadata starts with the header shown in Table 2.
ID_GBD_SPACE
ID_PRECISION
ID_PROFILE
– 10 – IEC 61966-12-1:2020 RLV © IEC 2020
Table 2 – Header of Gamut ID metadata
Byte # Size Symbols Description Values
hex Bytes
7 6 5 4 3 2 1 0
00 1 N, P R R = reserved = 0b0 (1bit)
ID_PROFILE (2 bits):
0b00: Full profile
0b01: Medium profile
0b10: Simple profile
0b11: Reserved
ID_PRECISION (2 bits):
0b00: 8 bits
0b01: 10 bits
0b10: 12 bits
0b11: Reserved
ID_GBD_SPACE (3bits):
0b000: ITU-R BT.709 RGB
0b001: xvYCC-601
(IEC 61966-2-4 -SD) YCC
0b010: xvYCC-709
(IEC 61966-2-4 -HD) YCC
0b011: XYZ (see below)
0b100: Reserved ITU-R BT.2020
R’G’B’
0b101: Reserved ITU-R BT.2020
Y’C’ C’
B R
0b110: Reserved ITU-R BT.2020
Y ’C’ C’
C BC RC
0b111: Reserved
ID_GBD_SPACE_EXT
01 2 ID_G Byte # of start of the description of gamut [0h0009;0hFFFF]
geometry
03 2 ID_E Byte # of start of the description of colour [0;0hFFFF]
reproduction
05 2 Reserved. Shall be zero. 0h0000
07 2 Reserved. Shall be zero. 0h0000
Byte # Size Symbols Description Values
hex Bytes
05 1 ID_GBD_SPACE_EXT 0h00: ITU-R BT.2100 R’G’B’ PQ
narrow
0h01: ITU-R BT.2100 R’G’B’ PQ
full
0h02: ITU-R BT.2100 R’G’B’
HLG narrow
0h03: ITU-R BT.2100 R’G’B’
HLG full
0h04: ITU-R BT.2100 Y’C’ C’
B R
PQ narrow
0h05: ITU-R BT.2100 Y’C’ C’
B R
PQ full
0h06: ITU-R BT.2100 Y’C’ C’
B R
HLG narrow
0h07: ITU-R BT.2100 Y’C’ C’
B R
HLG full
0h08: ITU-R BT.2100 IC C PQ
T P
narrow
0h09: ITU-R BT.2100 IC C PQ
T P
full
0h0A: ITU-R BT.2100 IC C HLG
T P
narrow
0h0B: ITU-R BT.2100 IC C HLG
T P
full
0h0C – 0hFF: reserved
06 3 Reserved. Shall be zero. 0h000000
ID_PROFILE indicates the profile of the Gamut ID metadata and shall be one of
• 0b00: Full profile,
• 0b01: Medium profile,
• 0b11: Simple profile.
ID_GBD_SPACE indicates the colour space and the colour space encoding for colour vertices
in the description of gamut geometry and shall be one of:
• 0b000: ITU-R BT.709, RGB space, encoding in accordance with SMPTE 274M,
• 0b001: xvYCC-601, YCbCr space, encoding in accordance with IEC 61966-2-4 – SD,
• 0b010: xvYCC-709, YCbCr space, encoding in accordance with IEC 61966-2-4 – HD,
• 0b011: XYZ; encoding shall use the XYZNumber format of ICC profiles specified in
ISO 15076-1:20052010 taking 12 bytes for one XYZ triple.
• 0b100: ITU-R BT.2020, RGB space, encoding in accordance with ITU-R BT.2020 R', G', B',
• 0b101: ITU-R BT.2020, YCbCr space', encoding in accordance with ITU-R BT.2020 Y', C' ,
B
C' ,
R
• 0b110: ITU-R BT.2020, YCbCr space, encoding in accordance with ITU-R BT.2020 Y ’, C’ ,
C BC
,
C’
RC
• 0b111: colour space and colour space encoding are indicated by ID_GBD_SPACE_EXT.
If ID_GBD_SPACE equals 0b111, ID_GBD_SPACE_EXT indicates the colour space and the
colour space encoding for colour vertices in the description of gamut geometry and shall be one
of:
• 0h00: ITU-R BT.2100 R’G’B’, PQ format, narrow range,
– 12 – IEC 61966-12-1:2020 RLV © IEC 2020
• 0h01: ITU-R BT.2100 R’G’B’, PQ format, full range,
• 0h02: ITU-R BT.2100 R’G’B’, HLG format, narrow range,
• 0h03: ITU-R BT.2100 R’G’B’, HLG format, full range,
• 0h04: ITU-R BT.2100 Y’C’ C’ , PQ format, narrow range,
B R
• 0h05: ITU-R BT.2100 Y’C’ C’ , PQ format, full range,
B R
• 0h06: ITU-R BT.2100 Y’C’ C’ , HLG format, narrow range,
B R
• 0h07: ITU-R BT.2100 Y’C’ C’ , HLG format, full range,
B R
• 0h08: ITU-R BT.2100 IC C , PQ format, narrow range,
T P
• 0h09: ITU-R BT.2100 IC C , PQ format, full range,
T P
• 0h0A: ITU-R BT.2100 IC C , HLG format, narrow range,
T P
• 0h0B: ITU-R BT.2100 IC C , HLG format, full range.
T P
aID_PRECISION ID_PRECISION, ID_GBD_SPACE and ID_GBD_SPACE_EXT specify, in
accordance with Table 3, the number N of bits that are used per colour channel in order to
define the coordinates of a colour in a colour space.
Table 3 – Bit depth for encoding of a colour space coordinate
ID_GBD_SPACE ID_PRECISION Bit depth N
0b000 or 0b00 8 bits
0b001 or 0b01 10 bits
0b010
0b10 12 bits
0b11 Reserved
0b011 Any 32 bits
0b100 or Any Reserved
0b101 or
0b110 or
0b111
ID_GBD_SPACE ID_PRECISION Bit depth N
0b011 Any 32 bits
else 0b00 8 bits
0b01 10 bits
0b10 12 bits
0b11 Reserved
If ID_GBD_SPACE equals 0b011 for XYZ encoding, bit depth N shall be 32 independent of
ID_PRECISION.
BT.2020 and BT.2100 encodings are defined by the ITU-R for bit depths of 10 or 12, only.
ID_G indicates the offset in bytes from the beginning of Gamut ID metadata to the beginning of
the description of gamut geometry.
If ID_E is different from 0h0000, the Gamut ID metadata contains a description of colour
reproduction and ID_E indicates the offset in bytes from the beginning of Gamut ID metadata
to the beginning of the description of colour reproduction. If ID_E has the value 0h0000, the
Gamut ID metadata does not contain a description of colour reproduction.
6 Description of gamut geometry (full profile)
6.1 General
In the header of Gamut ID metadata, if ID_PROFILE equals 0b00, the description of gamut
geometry shall correspond to the full profile.
6.2 Gamut geometry
The description of gamut geometry of the Gamut ID metadata describes the boundary of the
actual colour gamut. The description of gamut geometry starts at byte number ID_G.
The description of gamut geometry contains five sets of different elements:
• gamut instances,
• gamut hulls,
• gamut components,
• faces, and
• vertices.
The logical structure of the Gamut ID description of colour gamut is shown in Figure 1.
Figure 1 – Logical structure of the description of gamut geometry (full profile)
The description of gamut geometry contains one or more gamut boundary descriptions (GBD)
that each describes the boundary of the same actual colour gamut. A GBD contains vertices
and triangular faces. Each face is defined by the indices of three vertices.
A gamut component is a group of connex triangular faces. A GC is a part of a boundary
description. A GC is defined by one or more indices of faces.
A gamut hull (GH) is a group of connex gamut components building all together a closed surface.
This surface is the boundary description of a connex volume in CIEXYZ colour space. Each GH
is defined by one or more indices of GCs. A GH may refer to a single GC. In this case, the GC
must shall be a closed surface boundary description by itself. A GH may refer to a list of GCs,
in that case all GCs together build a closed surface boundary description of a connex volume.
A gamut instance (GI) is a group of gamut hulls building all together a valid GBD of the actual
colour gamut. A GI is defined by one or more indices of gamut hulls. A GI may refer to a single
GH; in this case, the single GH describes by itself the actual colour gamut. A GI may refer to a
list of GHs; in this case, the union of the volumes of the GHs describes the actual colour gamut.
The description of gamut geometry contains one or more different gamut instances. Each GI is
a complete and valid GBD. Two GIs differ in at least one of the following characteristics:
– 14 – IEC 61966-12-1:2020 RLV © IEC 2020
• Level of detail
The higher the level, the higher the number of faces.
• Non-convex shape
A GI may allow or not allow the use of non-convex shapes.
• Percentage of gamut colours
GIs may contain different percentages of the colours of the actual colour gamut.
A GI may have additional, optional characteristics:
• Inverted gamut components
A GC is used as inverted GC if it referenced by one or more GH assuming that its
surface orientation is inverted.
• Indication of gamut ridges
Vertices may be marked as gamut ridges if they correspond to positions on the surface
of the actual colour gamut having non-continuous surface curvature.
The description of gamut geometry is summarized in Table 4.
Table 4 – Description of gamut geometry
Byte # Description
hex
ID_G Header of description of gamut geometry
ID_GI Gamut instances
ID_GH Gamut hulls
ID_GC Gamut components
ID_F Faces
ID_V Vertices
6.3 Header of description of gamut geometry
The header of the description of gamut geometry follows the header of Gamut ID metadata and
is defined in accordance with Table 5.
Table 5 – Header of description of gamut geometry
Byte # Size Symbol Description Values decimal
hex bytes
ID_G 2 ID_GI Byte # of start of gamut instances [0;0hFFFF]
ID_G + 02 2 ID_GH Byte # of start of gamut hulls [0;0hFFFF]
ID_G + 04 2 ID_GC Byte # of start of gamut components [0;0hFFFF]
ID_G + 06 2 ID_F Byte # of start of faces [0;0hFFFF]
ID_G + 08 2 ID_V Byte # of start of vertices [0;0hFFFF]
ID_G + 0A 1 Reserved 0
ID_G + 0B 1 Reserved 0
ID_G + 0C 1 K Number of levels of detail 1 ≤ K ≤ 255
ID_G + 0D 2
F
1 <≤FF
MAX
MAX
Maximum number of faces in lowest level of detail
(F see Table 6)
ID_G + 0F 1 P Number of levels of colour population 0 < P ≤ 128/K
ID_G + 10 1 [0;200]
2Q
Double of percentages of gamut colours
ID_G + 11 1 [0;200]
2Q Double of percentages of gamut colours
:
:
ID_G + 10 + P-1 1 [0;200]
2Q
Double of percentages of gamut colours
P−1
ID_G + 10 + P 1 X Convex or non-convex shape 12≤≤X
X = 1: all GIs and all GHs shall be convex
X = 2: GIs and GHs may be convex or non-convex
16-bit integer or address values are encoded into 2 bytes using big endian, i.e. with the MSBs
in the first byte and the LSBs in the second byte.
ID_GI, ID_GH, ID_GC, ID_F and ID_V shall give the offset in bytes from the beginning of gamut
ID metadata to the beginning of gamut instances, gamut hulls, gamut components, faces and
vertices data, respectively.
K indicates the number of levels of details. The Gamut ID metadata contains at least K GIs. If
K = 1 there are no different level of details. Each GI is marked individually with a level of detail
(0, 1,…, K − 1), see Table 7.
F shall indicate the maximum number of faces for a GI having the lowest level of detail
MAX
(level 0). See Table 7 for definition of level of details. See Table 13 for the definition of faces.
P indicates the number of alternative GIs populated by different percentages of colours of the
actual colour gamut. If P > 1, there are P alternative GIs describing the same actual colour
gamut but containing different percentages of colours of the actual colour gamut. The Gamut
ID metadata contains at least P GIs. Each GI is marked individually with a population level
(0,1,…, P − 1), see Table 7.
2Q …2Q are the doubles of the percentages Q … Q of colours associated with the
0 P−1 0 P−1
population levels (0,1,…,P−1). A percentage shall approximately indicate how many percent of
colours (0…100) of the actual colour gamut are contained in the volume described by a GI of
the corresponding population level. As a matter of definition, Q … Q percentages can be
0 P−1
defined in steps of 0,5 points.
– 16 – IEC 61966-12-1:2020 RLV © IEC 2020
X indicates whether the Gamut ID uses only convex shapes (X = 1) or may use convex and non-
convex shapes (X = 2). When X = 1, each GI shall correspond to a convex shape and each GH
shall correspond to a convex shape. When X = 2, GIs are organized into pairs. Each pair
contains a first GI (marked as "convex", see Table 7) that corresponds to a convex shape and
which references only GHs that correspond to a convex shape. The second GI of the pair
(marked as "non convex", see Table 7) may correspond to a non-convex shape and may
reference GHs that correspond to non-convex shapes. The Gamut ID metadata contains at least
X GIs.
6.4 Gamut instances
The description of gamut geometry contains one or more gamut boundary descriptions of the
actual colour gamut. One single GBD is called gamut instance. A user of Gamut ID metadata
may use any one or any number of GIs of Gamut ID metadata. The GIs are defined by a list of
GIs from byte number ID_GI in accordance with Table 6. The order in the list is arbitrary but
fixed.
Table 6 – Gamut Instances
Byte # Size
Symbol Description Values
hex bytes
ID_GI 1 I Total number of I = X P K
Gamut Instances
ID_GI + 01 see Table 7
6+ H
Definition of GI no. 0,
ID_GI + 01 see Table 7
6+ H
Definition of GI no. 1
H
+ 6+
:
:
ID_GI + 01 see Table 7
6+ H
I −1
I −2
Definition of GI no. I-1
+ (6 + H )
i
∑
i=0
I is the number of GIs and shall be equal to the product of X, P and K as defined in Table 5.
The ith GI, i = 0…I − 1, is defined in accordance with Table 7.
Table 7 – ith gamut instance
Relative byte # Size
Symbol Description Values
hex bytes
00 1 K Level of detail of this
01≤KK≤ −
i
i
GI
GI GI i
01 2 Number of faces used
F FF≤ 2
i i MAX
by this GI
(F see Table 5)
MAX
GI GI
03 1 This GI defines a
X 1 ≤≤XX
i i
GI
convex shape ( X
i
(X see Table 5)
= 1) or may define a
non-convex shape
GI
( X =2)
i
04 1 P Level of colour
01≤ PP≤−
i
i
population of this GI
(P see Table 5)
05 1 H Number of gamut 1 ≤ H ≤ H
i i
hulls referenced by
this GI (H see Table 8)
06 H Indices of referenced [0; H − 1]
i
GHs
Shall be valid indices
of GH
K is the level of detail of the ith GI. The GI is of lowest level of detail is K = 0. If K is larger
i i i
than the level of detail K of a jth GI of same type (P = P , X = X ) then the ith GI has a higher
j i j i j
level of detail, i.e. a more precise geometric description, than the jth GI.
GI
F
is the number of faces used by the ith GI. This number should correspond to the number
i
of faces referenced by those gamut components (see Table 10) that are referenced by those
GI
F
gamut hulls (see Table 8) that are referenced by the ith GI. The number of faces should be
i
K
i
2 F see Table 6).
equal or smaller than (F
MAX MAX
GI GI
is an indicator of convex or non-convex shape. If = 1, the ith GI defines a convex
X X
i i
GI
shape and each GH referenced by the ith GI defines a convex shape by itself. If = 2, the
X
i
ith GI may define a convex or a non-convex shape and each of the GHs referenced by the ith
GI may define a convex or a non-convex shape by itself.
Q
P is the population level of the ith GI. The ith GI shall contain approximately percent of
P
i
i
colours of the actual colour gamut. Different GIs with same population level shall contain
approximately the same percentage of colours of the actual colour gamut. A GI with population
level P shall contain at least all colours of another GI with population level P if P > P , K = K
i j j i j i
and X = X .
j i
H is the number of gamut hulls that are referenced by the ith GI. If an ith GI references one
i
gamut hull, then H = 1 and the gamut hull describes the actual colour gamut. If an ith GI
i
references more than one gamut hull, then H > 1 and the union of the volumes of all referenced
i
gamut hulls describes the actual colour gamut.
– 18 – IEC 61966-12-1:2020 RLV © IEC 2020
The H indices of GHs have each one byte.
i
6.5 Gamut hulls
The description of gamut geometry contains one or more gamut hulls. Each GH is the closed
surface boundary description defining a connex, closed volume in colour space. A GH may be
referenced by one or more GIs. A GI may reference one or more GHs. A GH may describe by
itself the actual colour gamut or just a part of it. The GHs are defined by a list of GHs from byte
number ID_GH in accordance with Table 8. The order in the list is arbitrary but fixed.
H is the total number of GHs contained in the Gamut ID metadata. The hth GH, h = 0…H − 1, is
defined according to Table 9.
Table 8 – Gamut hulls
Byte # Size Symbol Description Values
hex bytes
ID_GH 1 H Total number of 0 ≤ H ≤ 255
Gamut Hulls
ID_GH + 01 Definition of GH no. 0 see Table 9
3+ C +
C
ID_GH + 01 Definition of GH no. 1 see Table 9
3+ C + C
1 1
+ 2+ C + C
0 0
:
:
ID_GH + 01 Definition of GH no. H see Table 9
3+ C + C
H −1 H −1
− 1
H −2
+ 3+CC+
( )
∑ hh
h=0
Table 9 – hth Gamut hull
Relative byte # Size Symbol Description Values
hex bytes
GH GH
00 1 Indication whether
X 1 ≤ X ≤ X
h h
this GH defines a
convex shape or any
(X see Table 5)
shape (convex or
GH
non-convex)
X =1: convex
h
shape
GH
X =2: convex or
h
non-convex shape
01 1 Number referenced
C
1 ≤ CC+ ≤ C
h kk
Gamut Components
that are used non-
(C see Table 10)
inverted by this GH
02 1 Number of referenced
C
Gamut Components
h
that are used inverted
by this GH
03 Indices of referenced [0; C − 1]
C
h
Gamut Components
shall be valid indices
of GCs
Indices of referenced
03 + C
h
C
Gamut Components
h
used in an inverted
manner
C C
+ is the number of gamut components that are referenced by the hth GH. If a hth GH
h h
C C
references one GC, then + = 1 and the GC defines by itself the closed surface of the
h h
C C
GH. If a hth GH references more than one GC, then + > 1 and all referenced GCs build
h h
together the closed surface of the GH. When a GC is used inverted, the surface normals of the
faces referenced by this GC are used in the inverse sense. For referenced faces, see Table 10.
For surface normals, see 6.7.
6.6 Gamut component
6.6.1 General
The description of gamut geometry contains one or more gamut components that each defines
a connex piece of a boundary description of a surface in CIEXYZ colour space. A GC may be
referenced by one or more GHs. A GH may reference one or more GCs. A GC may be the
boundary description of a closed surface in 3D colour space or a piece of it. The GCs are
defined by a list of
...
IEC 61966-12-1 ®
Edition 2.0 2020-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Multimedia systems and equipment – Colour measurement and management –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
Systèmes et appareils multimédias – Mesure et gestion de la couleur –
Partie 12-1: Métadonnées d'identification des gammes de couleurs (Gamut ID)
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IEC 61966-12-1 ®
Edition 2.0 2020-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Multimedia systems and equipment – Colour measurement and management –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
Systèmes et appareils multimédias – Mesure et gestion de la couleur –
Partie 12-1: Métadonnées d'identification des gammes de couleurs (Gamut ID)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.180.20; 33.160.40 ISBN 978-2-8322-8762-0
– 2 – IEC 61966-12-1:2020 © IEC 2020
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 8
4 Overview . 8
5 Header of Gamut ID metadata . 9
6 Description of gamut geometry (full profile) . 12
6.1 General . 12
6.2 Gamut geometry . 12
6.3 Header of description of gamut geometry . 14
6.4 Gamut Instances . 15
6.5 Gamut Hulls . 17
6.6 Gamut Component . 18
6.6.1 General . 18
6.6.2 Packing of face indices . 19
6.7 Faces. 20
6.7.1 General . 20
6.7.2 Packing of vertex indices . 21
6.8 Vertices . 21
6.8.1 General . 21
6.8.2 Packing of colour space coordinates for vertices . 22
7 Description of gamut geometry (medium and simple profiles) . 23
7.1 General . 23
7.2 Medium profile . 23
7.3 Simple profile . 23
8 Description of colour reproduction . 24
Annex A (informative) Size of Gamut ID metadata . 27
Annex B (informative) Motivation and requirements . 28
B.1 History . 28
B.2 Motivation . 28
B.3 Scope of Gamut ID metadata . 29
B.4 Requirements . 29
B.5 Structure . 30
B.6 Specific features . 32
Annex C (informative) Use of profiles . 34
C.1 Gamut ID profiles . 34
C.2 Medium profile . 34
C.3 Simple profile . 35
Annex D (informative) Example of Gamut ID metadata in simple profile . 36
Bibliography . 40
Figure 1 – Logical structure of the description of gamut geometry (full profile) . 13
Figure B.1 – Scope of Gamut ID – Generation and use of metadata are not specified . 29
Figure B.2 – Example of a description of gamut geometry in CIEXYZ colour space
consisting of a set of triangular faces . 30
Figure B.3 – Example of a gamut with identified ridge due to colorant channels . 33
Figure B.4 – Example of a non-convex gamut with two convex Gamut Hulls. 33
Table 1 – Format of Gamut ID metadata . 9
Table 2 – Header of Gamut ID metadata . 10
Table 3 – Bit depth for encoding of a colour space coordinate . 12
Table 4 – Description of gamut geometry . 14
Table 5 – Header of description of gamut geometry . 14
Table 6 – Gamut Instances . 15
Table 7 – ith Gamut Instance . 16
Table 8 – Gamut Hulls . 17
Table 9 – hth Gamut Hull . 18
Table 10 – Definition of Gamut Components . 19
Table 11 – cth Gamut Component . 19
Table 12 – Example for packing of Gamut Components . 20
Table 13 – Definition of faces . 20
Table 14 – Example for packing of faces . 21
Table 15 – Vertices . 22
Table 16 – Packing of 10-bit colour space coordinates . 22
Table 17 – Packing of 12-bit colour space coordinates . 23
Table 18 – Description of gamut geometry (simple profile) . 24
Table 19 – Header of description of gamut geometry (simple profile) . 24
Table 20 – Definition of vertices (simple profile) . 24
Table 21 – Header of description of colour reproduction . 25
Table B.1 – Requirements and Gamut ID features . 32
Table C.1 – Profiles for the description of gamut geometry . 34
Table D.1 – Colour gamut for digital cinema . 36
Table D.2 – Example for the header . 36
Table D.3 – Example for the header of description of gamut geometry . 37
Table D.4 – Example of definition of vertices . 37
Table D.5 – Encoded colour space coordinates for vertices . 37
– 4 – IEC 61966-12-1:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTIMEDIA SYSTEMS AND EQUIPMENT –
COLOUR MEASUREMENT AND MANAGEMENT –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61966-12-1 has been prepared by technical area 2: Colour
measurement and management, of IEC technical committee 100: Audio, video and multimedia
systems and equipment.
This second edition cancels and replaces the first edition published in 2011. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) ITU-R BT.2020 colour spaces added in Clause 6;
b) ITU-R BT.2100 colour spaces added in Clause 6.
The text of this International Standard is based on the following documents:
CDV Report on voting
100/3126/CDV 100/3375/RVC
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61966 series, published under the general title Multimedia systems
and equipment – colour measurement and management, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
– 6 – IEC 61966-12-1:2020 © IEC 2020
INTRODUCTION
New technologies in capturing and displaying wide-gamut colour images enable a new market
of wide-gamut video colour content and high dynamic range video content creation. Recent
video standards for wide gamut colour space encoding such as ITU-R BT.2020 (UHDTV) and
IEC 61966-2-4 (xvYCC) were established in order to be able to distribute content with a colour
gamut that is extended with respect to classical colour gamuts such as defined by colorimetry
standards ITU-R BT.601 (standard-definition television) and ITU-R BT.709 (high-definition
television). Recent video standards for high dynamic range (HDR) colour space encoding, such
as ITU-R BT.2100, were established in order to be able to distribute content with a colour gamut
and a dynamic range that are both extended with respect to classical colour encoding, such as
that defined by ITU-R BT.709. With the increasing popularity of wide gamut and high dynamic
range content and displays, the variety of colour gamuts of displays is expected to increase.
This issue can be an obstacle for adopting wide-gamut video colour content in professional
content creation since the compatibility of the content to the employed displays as well as the
compatibility among different displays is not ensured. The term display includes here any video
colour reproduction equipment, such as direct view displays and projectors. Thanks to
improvements of technology, the variety of colour gamut and colour reproduction capacities of
displays increases, while the colour gamut and the colour encoding rules of existing colour
space encoding standards are fixed.
To address this issue, this document specifies a colour gamut metadata scheme for video
systems including information for colour reproduction. This metadata can amend a video
content or a display. More specifically, improvements can be achieved if the wide-gamut colour
content is created with the knowledge of the display colour gamut as well as if the colour
reproduction in the display is done with the knowledge of the colour gamut of the pictorial
content.
This document permits video systems to define their own colour gamut. This document defines
necessary metadata that allows managing inhomogeneous video systems with different colour
gamuts. This document generalizes existing colour space encoding standards having a fixed
colour gamut.
MULTIMEDIA SYSTEMS AND EQUIPMENT –
COLOUR MEASUREMENT AND MANAGEMENT –
Part 12-1: Metadata for identification of colour gamut (Gamut ID)
1 Scope
This part of IEC 61966 defines the colour gamut metadata scheme for video systems and similar
applications.
The metadata can be associated with wide-gamut video colour content or to a piece of
equipment to display the content.
When associated with content, the colour gamut metadata defines the gamut for which the
content was created. It can be used by the display for controlled colour reproduction even if the
display’s colour gamut is different from that of the content.
When associated with a display, the colour gamut metadata defines the display colour gamut.
It can be used during content creation to enable improved colour reproduction.
The colour gamut metadata can cover associated colour encoding information, which includes
all information required for a controlled colour reproduction, when such information is not
provided by the colour encoding specification.
The colour gamut metadata scheme provides scalable solutions. For example, more flexible
solutions will be used for the professional use, while much simpler solutions will be used for
consumer use with easier product implementation.
This part of IEC 61966 only defines the colour gamut metadata scheme. Vendor-specific
solutions for creation and end-use of this metadata are allowed.
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.
IEC 60050-845, International electrochnical vocabulary – Chapter 845: Lighting
IEC 61966-2-4:2006, Multimedia systems and equipment – Colour measurement and
management – Part 2-4: Colour management – Extended-gamut YCC colour space for video
applications – xvYCC
ISO 15076-1:2010, Image technology colour management – Architecture, profile format and
data structure – Part 1: Based on ICC.1:2010
ITU-R BT.709, Parameter values for the HDTV standards for production and international
programme exchange
CIE 15:2004, Colorimetry
– 8 – IEC 61966-12-1:2020 © IEC 2020
SMPTE 274M:2005, SMPTE Standard for Television - 1920 x 1080 Image Sample Structure,
Digital Representation and Digital Timing Reference Sequences for Multiple Picture Rates
ITU-R BT.2020, Parameter values for ultra-high definition television systems for production and
international programme exchange
ITU-R BT.2100, Image parameter values for high dynamic range television for use in production
and international programme exchange
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-845 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
content
video content in production, post-production or consumption
3.1.2
gamut
solid in a colour space
Note 1 to entry: A solid in a colour space, such as specified by ITU-R BT.2100, can contain colours with high
luminance.
3.1.3
gamut boundary description
description of the boundary of a colour gamut
3.1.4
radiometrically-linear colour space coordinates
colour space coordinates that are linear with respect to image radiance
3.2 Abbreviated terms
GBD gamut boundary description
LSB least significant bit
MSB most significant bit
GI gamut instance
GH gamut hull
GC gamut component
4 Overview
This document specifies metadata called "Gamut ID metadata" providing information on an
actual colour gamut.
The Gamut ID metadata contains four parts and its format is summarized in Table 1.
Table 1 – Format of Gamut ID metadata
Byte # Metadata content
hex
0h0000 Header of Gamut ID metadata
ID_G Description of gamut geometry
ID_E Description of colour reproduction
Clause 5 specifies the header of Gamut ID metadata.
Clauses 6 and 7 specify the description of gamut geometry that corresponds to one of three
profiles as listed below:
• full profile;
• medium profile;
• simple profile.
Clause 6 specifies the full profile of the description of gamut geometry. The medium and simple
profiles are specified in Clause 7.
Clause 8 specifies the description of colour reproduction.
Annex A discusses the size of Gamut ID metadata.
Annex B gives background information.
Annex C discusses the use of simple, medium and full profiles.
5 Header of Gamut ID metadata
The Gamut ID metadata starts with the header shown in Table 2.
ID_GBD_SPACE
ID_PRECISION
ID_PROFILE
– 10 – IEC 61966-12-1:2020 © IEC 2020
Table 2 – Header of Gamut ID metadata
Byte # Size Symbols Description Values
hex Bytes
7 6 5 4 3 2 1 0
00 1 N, P R R = reserved = 0b0 (1bit)
ID_PROFILE (2 bits):
0b00: Full profile
0b01: Medium profile
0b10: Simple profile
0b11: Reserved
ID_PRECISION (2 bits):
0b00: 8 bits
0b01: 10 bits
0b10: 12 bits
0b11: Reserved
ID_GBD_SPACE (3bits):
0b000: ITU-R BT.709 RGB
0b001: xvYCC-601
(IEC 61966-2-4 -SD) YCC
0b010: xvYCC-709
(IEC 61966-2-4 -HD) YCC
0b011: XYZ (see below)
0b100: ITU-R BT.2020 R’G’B’
0b101: ITU-R BT.2020 Y’C’ C’
B R
0b110: ITU-R BT.2020
Y ’C’ C’
C BC RC
0b111: ID_GBD_SPACE_EXT
01 2 ID_G Byte # of start of the description of gamut [0h0009;0hFFFF]
geometry
03 2 ID_E Byte # of start of the description of colour [0;0hFFFF]
reproduction
05 1 ID_GBD_SPACE_EXT 0h00: ITU-R BT.2100 R’G’B’ PQ
narrow
0h01: ITU-R BT.2100 R’G’B’ PQ
full
0h02: ITU-R BT.2100 R’G’B’
HLG narrow
0h03: ITU-R BT.2100 R’G’B’
HLG full
0h04: ITU-R BT.2100 Y’C’ C’
B R
PQ narrow
0h05: ITU-R BT.2100 Y’C’ C’
B R
PQ full
0h06: ITU-R BT.2100 Y’C’ C’
B R
HLG narrow
0h07: ITU-R BT.2100 Y’C’ C’
B R
HLG full
0h08: ITU-R BT.2100 IC C PQ
T P
narrow
0h09: ITU-R BT.2100 ICTCP PQ
full
0h0A: ITU-R BT.2100 IC C HLG
T P
narrow
0h0B: ITU-R BT.2100 IC C HLG
T P
full
0h0C – 0hFF: reserved
06 3 Reserved. Shall be zero. 0h000000
ID_PROFILE indicates the profile of the Gamut ID metadata and shall be one of
• 0b00: Full profile,
• 0b01: Medium profile,
• 0b11: Simple profile.
ID_GBD_SPACE indicates the colour space and the colour space encoding for colour vertices
in the description of gamut geometry and shall be one of:
• 0b000: ITU-R BT.709, RGB space, encoding in accordance with SMPTE 274M,
• 0b001: xvYCC-601, YCbCr space, encoding in accordance with IEC 61966-2-4 – SD,
• 0b010: xvYCC-709, YCbCr space, encoding in accordance with IEC 61966-2-4 – HD,
• 0b011: XYZ; encoding shall use the XYZNumber format of ICC profiles specified in
ISO 15076-1:2010 taking 12 bytes for one XYZ triple.
• 0b100: ITU-R BT.2020, RGB space, encoding in accordance with ITU-R BT.2020 R', G', B',
• 0b101: ITU-R BT.2020, YCbCr space', encoding in accordance with ITU-R BT.2020 Y', C' ,
B
C' ,
R
• 0b110: ITU-R BT.2020, YCbCr space, encoding in accordance with ITU-R BT.2020 Y ’, C’ ,
C BC
C’ ,
RC
• 0b111: colour space and colour space encoding are indicated by ID_GBD_SPACE_EXT.
If ID_GBD_SPACE equals 0b111, ID_GBD_SPACE_EXT indicates the colour space and the
colour space encoding for colour vertices in the description of gamut geometry and shall be one
of:
• 0h00: ITU-R BT.2100 R’G’B’, PQ format, narrow range,
• 0h01: ITU-R BT.2100 R’G’B’, PQ format, full range,
• 0h02: ITU-R BT.2100 R’G’B’, HLG format, narrow range,
• 0h03: ITU-R BT.2100 R’G’B’, HLG format, full range,
• 0h04: ITU-R BT.2100 Y’C’ C’ , PQ format, narrow range,
B R
• 0h05: ITU-R BT.2100 Y’C’ C’ , PQ format, full range,
B R
• 0h06: ITU-R BT.2100 Y’C’ C’ , HLG format, narrow range,
B R
• 0h07: ITU-R BT.2100 Y’C’ C’ , HLG format, full range,
B R
• 0h08: ITU-R BT.2100 IC C , PQ format, narrow range,
T P
• 0h09: ITU-R BT.2100 IC C , PQ format, full range,
T P
• 0h0A: ITU-R BT.2100 IC C , HLG format, narrow range,
T P
• 0h0B: ITU-R BT.2100 IC C , HLG format, full range.
T P
ID_PRECISION, ID_GBD_SPACE and ID_GBD_SPACE_EXT specify, in accordance with
Table 3, the number N of bits that are used per colour channel in order to define the coordinates
of a colour in a colour space.
– 12 – IEC 61966-12-1:2020 © IEC 2020
Table 3 – Bit depth for encoding of a colour space coordinate
ID_GBD_SPACE ID_PRECISION Bit depth N
0b011 Any 32 bits
else 0b00 8 bits
0b01 10 bits
0b10 12 bits
0b11 Reserved
If ID_GBD_SPACE equals 0b011 for XYZ encoding, bit depth N shall be 32 independent of
ID_PRECISION.
BT.2020 and BT.2100 encodings are defined by the ITU-R for bit depths of 10 or 12, only.
ID_G indicates the offset in bytes from the beginning of Gamut ID metadata to the beginning of
the description of gamut geometry.
If ID_E is different from 0h0000, the Gamut ID metadata contains a description of colour
reproduction and ID_E indicates the offset in bytes from the beginning of Gamut ID metadata
to the beginning of the description of colour reproduction. If ID_E has the value 0h0000, the
Gamut ID metadata does not contain a description of colour reproduction.
6 Description of gamut geometry (full profile)
6.1 General
In the header of Gamut ID metadata, if ID_PROFILE equals 0b00, the description of gamut
geometry shall correspond to the full profile.
6.2 Gamut geometry
The description of gamut geometry of the Gamut ID metadata describes the boundary of the
actual colour gamut. The description of gamut geometry starts at byte number ID_G.
The description of gamut geometry contains five sets of different elements:
• gamut instances,
• gamut hulls,
• gamut components,
• faces, and
• vertices.
The logical structure of the Gamut ID description of colour gamut is shown in Figure 1.
Figure 1 – Logical structure of the description of gamut geometry (full profile)
The description of gamut geometry contains one or more gamut boundary descriptions (GBD)
that each describes the boundary of the same actual colour gamut. A GBD contains vertices
and triangular faces. Each face is defined by the indices of three vertices.
A gamut component is a group of connex triangular faces. A GC is a part of a boundary
description. A GC is defined by one or more indices of faces.
A gamut hull (GH) is a group of connex gamut components building all together a closed surface.
This surface is the boundary description of a connex volume in CIEXYZ colour space. Each GH
is defined by one or more indices of GCs. A GH may refer to a single GC. In this case, the GC
shall be a closed surface boundary description by itself. A GH may refer to a list of GCs, in that
case all GCs together build a closed surface boundary description of a connex volume.
A gamut instance (GI) is a group of gamut hulls building all together a valid GBD of the actual
colour gamut. A GI is defined by one or more indices of gamut hulls. A GI may refer to a single
GH; in this case, the single GH describes by itself the actual colour gamut. A GI may refer to a
list of GHs; in this case, the union of the volumes of the GHs describes the actual colour gamut.
The description of gamut geometry contains one or more different gamut instances. Each GI is
a complete and valid GBD. Two GIs differ in at least one of the following characteristics:
• Level of detail
The higher the level, the higher the number of faces.
• Non-convex shape
A GI may allow or not allow the use of non-convex shapes.
• Percentage of gamut colours
GIs may contain different percentages of the colours of the actual colour gamut.
A GI may have additional, optional characteristics:
• Inverted gamut components
A GC is used as inverted GC if it referenced by one or more GH assuming that its
surface orientation is inverted.
• Indication of gamut ridges
Vertices may be marked as gamut ridges if they correspond to positions on the surface
of the actual colour gamut having non-continuous surface curvature.
The description of gamut geometry is summarized in Table 4.
– 14 – IEC 61966-12-1:2020 © IEC 2020
Table 4 – Description of gamut geometry
Byte # Description
hex
ID_G Header of description of gamut geometry
ID_GI Gamut instances
ID_GH Gamut hulls
ID_GC Gamut components
ID_F Faces
ID_V Vertices
6.3 Header of description of gamut geometry
The header of the description of gamut geometry follows the header of Gamut ID metadata and
is defined in accordance with Table 5.
Table 5 – Header of description of gamut geometry
Byte # Size Symbol Description Values decimal
hex bytes
ID_G 2 ID_GI Byte # of start of gamut instances [0;0hFFFF]
ID_G + 02 2 ID_GH Byte # of start of gamut hulls [0;0hFFFF]
ID_G + 04 2 ID_GC Byte # of start of gamut components [0;0hFFFF]
ID_G + 06 2 ID_F Byte # of start of faces [0;0hFFFF]
ID_G + 08 2 ID_V Byte # of start of vertices [0;0hFFFF]
ID_G + 0A 1 Reserved 0
ID_G + 0B 1 Reserved 0
ID_G + 0C 1 K Number of levels of detail 1 ≤ K ≤ 255
ID_G + 0D 2
F
1<≤FF
MAX
MAX
Maximum number of faces in lowest level of detail
(F see Table 6)
ID_G + 0F 1 P Number of levels of colour population 0 < P ≤ 128/K
ID_G + 10 1 [0;200]
2Q
Double of percentages of gamut colours
ID_G + 11 1 [0;200]
2Q Double of percentages of gamut colours
:
:
ID_G + 10 + P-1 1 [0;200]
2Q
Double of percentages of gamut colours
P−1
ID_G + 10 + P 1 X Convex or non-convex shape 12≤≤X
X = 1: all GIs and all GHs shall be convex
X = 2: GIs and GHs may be convex or non-convex
16-bit integer or address values are encoded into 2 bytes using big endian, i.e. with the MSBs
in the first byte and the LSBs in the second byte.
ID_GI, ID_GH, ID_GC, ID_F and ID_V shall give the offset in bytes from the beginning of gamut
ID metadata to the beginning of gamut instances, gamut hulls, gamut components, faces and
vertices data, respectively.
K indicates the number of levels of details. The Gamut ID metadata contains at least K GIs. If
K = 1 there are no different level of details. Each GI is marked individually with a level of detail
(0, 1,…, K − 1), see Table 7.
F shall indicate the maximum number of faces for a GI having the lowest level of detail
MAX
(level 0). See Table 7 for definition of level of details. See Table 13 for the definition of faces.
P indicates the number of alternative GIs populated by different percentages of colours of the
actual colour gamut. If P > 1, there are P alternative GIs describing the same actual colour
gamut but containing different percentages of colours of the actual colour gamut. The Gamut
ID metadata contains at least P GIs. Each GI is marked individually with a population level
(0,1,…, P − 1), see Table 7.
2Q …2Q are the doubles of the percentages Q … Q of colours associated with the
0 P−1 0 P−1
population levels (0,1,…,P−1). A percentage shall approximately indicate how many percent of
colours (0…100) of the actual colour gamut are contained in the volume described by a GI of
the corresponding population level. As a matter of definition, Q … Q percentages can be
0 P−1
defined in steps of 0,5 points.
X indicates whether the Gamut ID uses only convex shapes (X = 1) or may use convex and non-
convex shapes (X = 2). When X = 1, each GI shall correspond to a convex shape and each GH
shall correspond to a convex shape. When X = 2, GIs are organized into pairs. Each pair
contains a first GI (marked as "convex", see Table 7) that corresponds to a convex shape and
which references only GHs that correspond to a convex shape. The second GI of the pair
(marked as "non convex", see Table 7) may correspond to a non-convex shape and may
reference GHs that correspond to non-convex shapes. The Gamut ID metadata contains at least
X GIs.
6.4 Gamut instances
The description of gamut geometry contains one or more gamut boundary descriptions of the
actual colour gamut. One single GBD is called gamut instance. A user of Gamut ID metadata
may use any one or any number of GIs of Gamut ID metadata. The GIs are defined by a list of
GIs from byte number ID_GI in accordance with Table 6. The order in the list is arbitrary but
fixed.
Table 6 – Gamut Instances
Byte # Size
Symbol Description Values
hex bytes
ID_GI 1 I Total number of I = X P K
Gamut Instances
ID_GI + 01 see Table 7
6+ H Definition of GI no. 0,
ID_GI + 01 see Table 7
6+
H
Definition of GI no. 1
+ 6+ H
:
:
ID_GI + 01 see Table 7
6+ H
I−1
I−2
Definition of GI no. I-1
(6+ H)
+
∑ i
i=0
– 16 – IEC 61966-12-1:2020 © IEC 2020
I is the number of GIs and shall be equal to the product of X, P and K as defined in Table 5.
The ith GI, i = 0…I − 1, is defined in accordance with Table 7.
Table 7 – ith gamut instance
Relative byte # Size
Symbol Description Values
hex bytes
00 1 K Level of detail of this
01≤KK≤ −
i i
GI
GI
01 2 Number of faces used GI i
F
i FF≤ 2
i MAX
by this GI
(F see Table 5)
MAX
03 1 GI This GI defines a GI
X 1≤≤XX
i i
GI
convex shape ( X =
i
(X see Table 5)
1) or may define a
non-convex shape
GI
( X =2)
i
04 1 P Level of colour
01≤ PP≤−
i
i
population of this GI
(P see Table 5)
H
05 1 Number of gamut 1 ≤ H ≤ H
i
i
hulls referenced by
(H see Table 8)
this GI
06 H Indices of referenced [0; H − 1]
i
GHs
Shall be valid indices
of GH
K is the level of detail of the ith GI. The GI is of lowest level of detail is K = 0. If K is larger
i i i
than the level of detail K of a jth GI of same type (P = P , X = X ) then the ith GI has a higher
j i j i j
level of detail, i.e. a more precise geometric description, than the jth GI.
GI
F is the number of faces used by the ith GI. This number should correspond to the number
i
of faces referenced by those gamut components (see Table 10) that are referenced by those
GI
gamut hulls (see Table 8) that are referenced by the ith GI. The number F of faces should be
i
K
i
equal or smaller than 2 F (F see Table 6).
MAX
MAX
GI GI
is an indicator of convex or non-convex shape. If = 1, the ith GI defines a convex
X X
i i
GI
shape and each GH referenced by the ith GI defines a convex shape by itself. If = 2, the
X
i
ith GI may define a convex or a non-convex shape and each of the GHs referenced by the ith
GI may define a convex or a non-convex shape by itself.
P is the population level of the ith GI. The ith GI shall contain approximately Q percent of
i P
i
colours of the actual colour gamut. Different GIs with same population level shall contain
approximately the same percentage of colours of the actual colour gamut. A GI with population
shall contain at least all colours of another GI with population level P if P > P , K = K
level P
i j j i j i
and X = X .
j i
H is the number of gamut hulls that are referenced by the ith GI. If an ith GI references one
i
gamut hull, then H = 1 and the gamut hull describes the actual colour gamut. If an ith GI
i
references more than one gamut hull, then H > 1 and the union of the volumes of all referenced
i
gamut hulls describes the actual colour gamut.
The H indices of GHs have each one byte.
i
6.5 Gamut hulls
The description of gamut geometry contains one or more gamut hulls. Each GH is the closed
surface boundary description defining a connex, closed volume in colour space. A GH may be
referenced by one or more GIs. A GI may reference one or more GHs. A GH may describe by
itself the actual colour gamut or just a part of it. The GHs are defined by a list of GHs from byte
number ID_GH in accordance with Table 8. The order in the list is arbitrary but fixed.
H is the total number of GHs contained in the Gamut ID metadata. The hth GH, h = 0…H − 1, is
defined according to Table 9.
Table 8 – Gamut hulls
Byte # Size Symbol Description Values
hex bytes
ID_GH 1 H Total number of 0 ≤ H ≤ 255
Gamut Hulls
ID_GH + 01 Definition of GH no. 0 see Table 9
3+ C + C
0 0
ID_GH + 01 Definition of GH no. 1 see Table 9
3+ +
C C
1 1
+ 2+ C + C
0 0
:
:
ID_GH + 01 Definition of GH no. H see Table 9
3+ C +
C
H−1 H−1
− 1
H−2
+ 3+CC+
( )
∑
hh
h=0
– 18 – IEC 61966-12-1:2020 © IEC 2020
Table 9 – hth Gamut hull
Relative byte # Size Symbol Description Values
hex bytes
...
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