ISO/IEC 23091-2:2021
(Main)Information technology — Coding-independent code points — Part 2: Video
Information technology — Coding-independent code points — Part 2: Video
This document defines various code points and fields that establish properties of a video (or still image) representation and are independent of the compression encoding and bit rate. These properties can describe the appropriate interpretation of decoded data or can, similarly, describe the characteristics of such a signal before the signal is compressed by an encoder that is suitable for compressing such an input signal.
Technologies de l'information — Points de code indépendants du codage — Partie 2: Vidéo
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INTERNATIONAL ISO/IEC
STANDARD 23091-2
Second edition
2021-10
Information technology — Coding-
independent code points —
Part 2:
Video
Technologies de l'information — Points de code indépendants du
codage —
Partie 2: Vidéo
Reference number
© ISO/IEC 2021
© ISO/IEC 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO/IEC 2021 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Conventions . 2
5.1 Arithmetic operators . 2
5.2 Bit-wise operators . 3
5.3 Assignment operators . 3
5.4 Relational, logical, and other operators . 3
5.5 Mathematical functions . 4
5.6 Order of operations . 5
6 Specified code points.6
7 Principles for definition and referencing of code points . 6
7.1 Application usage . 6
7.2 Code point encoding and defaults . 6
7.3 Externally defined values . 7
7.4 Reference format . 7
7.5 Uniform resource name format . 7
8 Video code points . 7
8.1 Colour primaries . 7
8.2 Transfer characteristics . 9
8.3 Matrix coefficients .12
8.4 Video frame packing type . 18
8.5 Packed video content interpretation . 24
8.6 Sample aspect ratio . 24
8.7 Chroma 4:2:0 sample location type . 25
Bibliography .29
iii
© ISO/IEC 2021 – All rights reserved
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work.
The procedures used to develop this document and those intended for its further maintenance
are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria
needed for the different types of document should be noted. This document was drafted in
accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or
www.iec.ch/members_experts/refdocs).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC
list of patent declarations received (see patents.iec.ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, in collaboration
with ITU-T [as Rec. ITU-T H.273 (07/2021)].
This second edition cancels and replaces the first edition (ISO/IEC 23091-2:2019), which has been
technically revised.
The main changes are as follows:
— the addition of a code point for chroma sampling grid alignment indication for the 4:2:0 colour
format;
— correction of the range of values specification for sample aspect ratio indication;
— correction of the formulae for the IC C colour representation for the hybrid-log-gamma (HLG)
T P
transfer function specified in Rec. ITU-R BT.2100-2;
— correction of the formulae for the transfer function for the sYCC colour representation specified in
IEC 61966-2-1.
A list of all parts in the ISO/IEC 23091 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.
iv
© ISO/IEC 2021 – All rights reserved
Introduction
In a number of specifications, there is a need to identify some characteristics of video (or still image)
media content that are logically independent of the compression format. These characteristics can
include, for example, aspects that relate to the sourcing or presentation, or the role of the video (or still
image) media component. These characteristics have typically been documented by fields that take an
encoded value or item selected from an enumerated list, herein called code points.
These code points are typically defined in the specification of compression formats to document these
characteristics of the media. In past practices, the definition of these fields has been copied from
document to document, sometimes with new values being added in later documents (and sometimes
with later amendments specified to add new entries to existing documents).
This past practice has raised a number of issues, including the following:
a) A lack of a formal way to avoid conflicting assignments being made in different documents.
b) Having additional values defined in later specifications that can be practically used with older
compression formats, but without clear formal applicability of these new values to older documents.
c) Any update or correction of code point semantics can incur significant effort to update all
documents in which the code point is specified, instead of enabling a single central specification to
apply across different referencing specifications.
d) The choice of reference for other specifications (such as container or delivery formats) not being
obvious; wherein a formal reference to a compression format document appears to favour that one
format over others, and also appears to preclude definitions defined in other compression format
specifications.
e) Burdensome maintenance needs to ensure that a reference to material defined in a compression
format specification is maintained appropriately over different revisions of the referenced format
specification, as the content of a compression format specification can change over time and is
ordinarily not intended as a point of reference for defining such code points.
This document provides a central definition of such code points for video and image applications
to address these issues. This document can be used to provide universal descriptions to assist
interpretation of video and image signals following decoding, or to describe the properties of these
signals before they are encoded.
v
© ISO/IEC 2021 – All rights reserved
INTERNATIONAL STANDARD ISO/IEC 23091-2:2021(E)
Information technology — Coding-independent code
points —
Part 2:
Video
1 Scope
This document defines various code points and fields that establish properties of a video (or still image)
representation and are independent of the compression encoding and bit rate. These properties can
describe the appropriate interpretation of decoded data or can, similarly, describe the characteristics
of such a signal before the signal is compressed by an encoder that is suitable for compressing such an
input signal.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/CIE 11664-1, Colorimetry — Part 1: CIE standard colorimetric observers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
bottom field
assembly of the odd-numbered rows of samples of the components (3.3) of a video frame using a
numbering of rows that starts with row number 0 as the top row
3.2
chroma
sample array or single sample representing one of the two colour difference signals related to the
primary colours, represented by the symbols Cb and Cr
Note 1 to entry: The term "chroma" is used rather than "chrominance" in order to avoid the implication of the use
of linear light transfer characteristics that is often associated with "chrominance".
3.3
component
array or single sample from one of the three arrays [luma (3.4) and two chroma (3.2)] that compose
a picture (3.5) in 4:2:0, 4:2:
...
INTERNATIONAL ISO/IEC
STANDARD 23091-2
Second edition
2021-10
Information technology — Coding-
independent code points —
Part 2:
Video
Technologies de l'information — Points de code indépendants du
codage —
Partie 2: Vidéo
Reference number
© ISO/IEC 2021
© ISO/IEC 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO/IEC 2021 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Conventions . 2
5.1 Arithmetic operators . 2
5.2 Bit-wise operators . 3
5.3 Assignment operators . 3
5.4 Relational, logical, and other operators . 3
5.5 Mathematical functions . 4
5.6 Order of operations . 5
6 Specified code points.6
7 Principles for definition and referencing of code points . 6
7.1 Application usage . 6
7.2 Code point encoding and defaults . 6
7.3 Externally defined values . 7
7.4 Reference format . 7
7.5 Uniform resource name format . 7
8 Video code points . 7
8.1 Colour primaries . 7
8.2 Transfer characteristics . 9
8.3 Matrix coefficients .12
8.4 Video frame packing type . 18
8.5 Packed video content interpretation . 24
8.6 Sample aspect ratio . 24
8.7 Chroma 4:2:0 sample location type . 25
Bibliography .29
iii
© ISO/IEC 2021 – All rights reserved
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work.
The procedures used to develop this document and those intended for its further maintenance
are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria
needed for the different types of document should be noted. This document was drafted in
accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or
www.iec.ch/members_experts/refdocs).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC
list of patent declarations received (see patents.iec.ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, in collaboration
with ITU-T [as Rec. ITU-T H.273 (07/2021)].
This second edition cancels and replaces the first edition (ISO/IEC 23091-2:2019), which has been
technically revised.
The main changes are as follows:
— the addition of a code point for chroma sampling grid alignment indication for the 4:2:0 colour
format;
— correction of the range of values specification for sample aspect ratio indication;
— correction of the formulae for the IC C colour representation for the hybrid-log-gamma (HLG)
T P
transfer function specified in Rec. ITU-R BT.2100-2;
— correction of the formulae for the transfer function for the sYCC colour representation specified in
IEC 61966-2-1.
A list of all parts in the ISO/IEC 23091 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.
iv
© ISO/IEC 2021 – All rights reserved
Introduction
In a number of specifications, there is a need to identify some characteristics of video (or still image)
media content that are logically independent of the compression format. These characteristics can
include, for example, aspects that relate to the sourcing or presentation, or the role of the video (or still
image) media component. These characteristics have typically been documented by fields that take an
encoded value or item selected from an enumerated list, herein called code points.
These code points are typically defined in the specification of compression formats to document these
characteristics of the media. In past practices, the definition of these fields has been copied from
document to document, sometimes with new values being added in later documents (and sometimes
with later amendments specified to add new entries to existing documents).
This past practice has raised a number of issues, including the following:
a) A lack of a formal way to avoid conflicting assignments being made in different documents.
b) Having additional values defined in later specifications that can be practically used with older
compression formats, but without clear formal applicability of these new values to older documents.
c) Any update or correction of code point semantics can incur significant effort to update all
documents in which the code point is specified, instead of enabling a single central specification to
apply across different referencing specifications.
d) The choice of reference for other specifications (such as container or delivery formats) not being
obvious; wherein a formal reference to a compression format document appears to favour that one
format over others, and also appears to preclude definitions defined in other compression format
specifications.
e) Burdensome maintenance needs to ensure that a reference to material defined in a compression
format specification is maintained appropriately over different revisions of the referenced format
specification, as the content of a compression format specification can change over time and is
ordinarily not intended as a point of reference for defining such code points.
This document provides a central definition of such code points for video and image applications
to address these issues. This document can be used to provide universal descriptions to assist
interpretation of video and image signals following decoding, or to describe the properties of these
signals before they are encoded.
v
© ISO/IEC 2021 – All rights reserved
INTERNATIONAL STANDARD ISO/IEC 23091-2:2021(E)
Information technology — Coding-independent code
points —
Part 2:
Video
1 Scope
This document defines various code points and fields that establish properties of a video (or still image)
representation and are independent of the compression encoding and bit rate. These properties can
describe the appropriate interpretation of decoded data or can, similarly, describe the characteristics
of such a signal before the signal is compressed by an encoder that is suitable for compressing such an
input signal.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/CIE 11664-1, Colorimetry — Part 1: CIE standard colorimetric observers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
bottom field
assembly of the odd-numbered rows of samples of the components (3.3) of a video frame using a
numbering of rows that starts with row number 0 as the top row
3.2
chroma
sample array or single sample representing one of the two colour difference signals related to the
primary colours, represented by the symbols Cb and Cr
Note 1 to entry: The term "chroma" is used rather than "chrominance" in order to avoid the implication of the use
of linear light transfer characteristics that is often associated with "chrominance".
3.3
component
array or single sample from one of the three arrays [luma (3.4) and two chroma (3.2)] that compose
a picture (3.5) in 4:2:0, 4:2:
...
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