ISO/IEC 15444-17:2023
(Main)Information technology — JPEG 2000 image coding system — Part 17: Extensions for coding of discontinuous media
Information technology — JPEG 2000 image coding system — Part 17: Extensions for coding of discontinuous media
This document defines QuadBPT and TriBPT image components, collectively known as "breakpoint components", and specifies decoding and reconstruction procedures for recovering breakpoint component sample values from the codestream. This Recommendation | International Standard also specifies "breakpoint-dependent" spatial wavelet transforms that can be used in place of the transforms specified in Recommendation ITU-T T.800 | ISO/IEC 15444-1 for selected image components or tile-components. Extensions to the codestream syntax of Rec. ITU‑T T.800 | ISO/IEC 15444-1 are specified to enable the identification of breakpoint components, of components that can use a breakpoint-dependent spatial wavelet transform, and the association of breakpoint components with such breakpoint-dependent wavelet transforms.
Technologies de l'information — Système de codage d'images JPEG 2000 — Partie 17: Extensions pour le codage des supports discontinus
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INTERNATIONAL ISO/IEC
STANDARD 15444-17
First edition
2023-06
Information technology — JPEG 2000
image coding system —
Part 17:
Extensions for coding of discontinuous
media
Technologies de l'information — Système de codage d'images JPEG
2000 —
Partie 17: Extensions pour le codage des supports discontinus
Reference number
ISO/IEC 15444-17:2023(E)
© ISO/IEC 2023
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ISO/IEC 15444-17:2023(E)
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ISO/IEC 15444-17:2023(E)
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.
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 https://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 ITU-T (as ITU-T - T.816) and drafted in accordance with its editorial
rules, in collaboration with Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO/IEC 15444 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.
© ISO/IEC 2023 – All rights reserved iii
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ISO/IEC 15444-17:2023 (E)
INTERNATIONAL STANDARD ISO/IEC 15444-17
RECOMMENDATION ITU-T T.816 (V1)
Information technology – JPEG 2000 image coding system:
Extensions for coding of discontinuous media
Summary
Rec. ITU-T T.816 | ISO/IEC 15444-17 provides extensions of the scalable image coding tools described in
Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801 | ISO/IEC 15444-2, of two types. First, new wavelet-like
image transforms known as "breakpoint-dependent" transforms are defined, whose underlying basis functions can be
discontinuous at defined locations within the image component to which they are applied. Second, new scalable coding
tools are described for a new type of image component known as a "breakpoint component", which provides a successively
refinable and hierarchical description of the breakpoint locations used by the breakpoint-dependent transforms. Any non-
initial component or components within a codestream conforming to this Recommendation | International Standard can be
breakpoint components and any of the components in the codestream other than breakpoint components can use a
breakpoint-dependent transform that depends upon one of the breakpoint components in the same codestream. These new
tools together allow for the scalable coding of imagery that naturally exhibits strong discontinuities in the spatial domain.
An important example of such imagery is depth maps.
This Recommendation was developed jointly with ISO/IEC JTC 1/SC 29/WG 1 (JPEG) and is common text with
ISO/IEC 15444-17.
History
*
Edition Recommendation Approval Study Group Unique ID
1.0 ITU-T T.816 (V1) 2023-02-13 16 11.1002/1000/15206
*
To access the Recommendation, type the URL http://handle.itu.int/ in the address field of your web browser,
followed by the Recommendation's unique ID. For example, http://handle.itu.int/11.1002/1000/11830-en.
iv Rec. ITU-T T.816 (V1) (02/2023)
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ISO/IEC 15444-17:2023 (E)
FOREWORD
The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of
telecommunications, information and communication technologies (ICTs). The ITU Telecommunication
Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical,
operating and tariff questions and issuing Recommendations on them with a view to standardizing
telecommunications on a worldwide basis.
The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes
the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
In some areas of information technology which fall within ITU-T's purview, the necessary standards are
prepared on a collaborative basis with ISO and IEC.
NOTE
In this Recommendation, the expression "Administration" is used for conciseness to indicate both a
telecommunication administration and a recognized operating agency.
Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain
mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the
Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other
obligatory language such as "must" and the negative equivalents are used to express requirements. The use of
such words does not suggest that compliance with the Recommendation is required of any party.
INTELLECTUAL PROPERTY RIGHTS
ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve
the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or
applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of
the Recommendation development process.
As of the date of approval of this Recommendation, ITU had not received notice of intellectual property,
protected by patents/software copyrights, which may be required to implement this Recommendation.
However, implementers are cautioned that this may not represent the latest information and are therefore
strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at
http://www.itu.int/ITU-T/ipr/.
© ITU 2023
All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior
written permission of ITU.
Rec. ITU-T T.816 (V1) (02/2023) v
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ISO/IEC 15444-17:2023 (E)
CONTENTS
Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviations . 2
5 5 Conventions . 3
6 Conformance . 3
6.1 Codestream conformance . 3
6.2 Decoder. 3
7 Breakpoint component structure. 4
7.1 Breakpoint components and the reference grid. 4
7.2 Division of breakpoint resolutions into cells, arcs and the CL band. 4
7.3 Division of breakpoint resolutions into precincts and code-blocks . 5
7.4 Root and non-root arc breakpoint associations . 7
7.5 Breakpoint values and vertices . 8
8 Breakpoint-dependent spatial wavelet transformation . 10
8.1 Overview . 10
8.2 TriBPT-dependent irreversible transforms . 11
8.2.1 Introduction . 11
8.2.2 Arcs with tb=0 . 12
8.2.3 Arcs with tb=3 . 13
8.2.4 Arcs with tb=2 . 13
8.2.5 Arcs with tb=1 . 17
8.3 TriBPT-dependent reversible transforms . 21
8.3.1 Arcs with tb=0 . 22
8.3.2 Arcs with tb=3 . 22
8.3.3 Arcs with tb=2 . 22
8.3.4 Arcs with tb=1 . 22
8.4 QuadBPT-dependent transforms. 23
8.4.1 Introduction . 23
8.4.2 BD_2D_SR phase 1 . 24
8.4.3 BD_2D_SR phase 2 . 26
9 Decoding of breakpoint code-blocks . 28
9.1 Embedded bit-plane decoding of breakpoints. 28
9.2 Inter-band coding mode (BPT_INTER) . 29
9.3 Cell-based scanning patterns and CBAP-based block flipping. 30
9.4 QuadBPT decoding procedures . 32
9.4.1 MQ Coder contexts and initial states for QuadBPT decoding . 32
9.4.2 Derivation of context labels for QuadBPT CL band significance coding passes . 33
9.4.3 Non-root significance decoding for QuadBPT CL code-blocks . 35
9.4.4 Root significance decoding for QuadBPT CL code-blocks . 36
9.4.5 Root significance decoding for QuadBPT LL code-blocks . 37
9.4.6 Position refinement decoding for QuadBPT code-blocks . 37
9.5 TriBPT decoding procedures . 38
9.5.1 MQ Coder contexts and initial states for TriBPT decoding . 38
9.5.2 Derivation of context labels for TriBPT CL band significance coding passes. 39
9.5.3 Non-root significance decoding for TriBPT CL code-blocks . 42
9.5.4 Root significance decoding for TriBPT CL code-blocks . 43
9.5.5 Root significance decoding for TriBPT LL code-blocks . 44
9.5.6 Position refinement decoding for TriBPT code-blocks . 45
9.6 Quality layers and packets for breakpoint components . 45
10 Reconstruction of breakpoint components . 47
10.1 Overview . 47
10.2 Direct induction step . 47
10.2.1 Introduction . 47
10.2.2 Extrapolation Qualifier for TriBPT direct induction. 48
vi Rec. ITU-T T.816 (V1) (02/2023)
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ISO/IEC 15444-17:2023 (E)
Page
10.3 QuadBPT spatial induction . 49
10.3.1 Introduction . 49
10.4 TriBPT spatial induction. 51
10.4.1 TriBPT induction modes and corner notation . 51
10.4.2 4-arc mode . 51
10.4.3 3-arc mode . 52
10.4.4 Extrapolation qualifier for TriBPT spatial induction . 53
10.4.5 Rounding policies for TriBPT spatial induction . 56
10.4.6 Image boundary handling for TriBPT . 56
(This annex forms an integral part of this Recommendation | International Standard.) – Codestream syntax . 58
A.1 General . 58
A.2 SIZ marker segment. 58
A.3 CAP marker segment . 58
A.4 Hierarchical data type (HDT) marker segment . 59
A.5 COD and COC marker segments . 59
(This annex does not form an integral part of this Recommendation | International Standard) –
Hierarchical breakpoint encapsulation and raw file format . 62
B.1 General . 62
B.2 Raster organization of breakpoints . 62
B.3 16- and 32-bit packed breakpoint values . 63
B.4 A raw file format for breakpoints . 64
Bibliography . 67
List of Tables
Page
Table 1 – Constraints on PPx and PPy precinct size parameters breakpoint components . 6
Table 2 – MQ coder contexts for QuadBPT CL code-block decoding passes. State index values correspond
to the Qe values and probability estimation transitions tabulated in Rec. ITU-T T.800 | ISO/IEC 15444-1 . 33
Table 3 – Context labels from Table 2 that are used for QuadBPT LL code-block decoding passes . 33
Table 4 – MQ coder contexts for TriBPT CL code-block decoding passes. State index values correspond to the Qe
values and probability estimation transitions tabulated in Rec. ITU-T T.800 | ISO/IEC 15444-1 . 38
Table 5 – Context labels from Table 4 that are used for TriBPT LL code-block decoding passes. 38
Table A.1 – Extensions and constraints to marker segments specified in Rec. ITU-T T.800 | ISO/IEC 15444-1
and new marker segments specified in this Recommendation | International Standard . 58
17
Table A.2 – Ccap Syntax and Semantics . 58
Table A.3 – Hierarchical data type parameter values . 59
i
Table A.4 – Allowed values for Ihdt . 59
Table A.5 – Scod and Scoc semantics for bit 5 . 60
Table A.6 – SXcod bit fields specified by this Recommendation | International Standard . 60
Table A.7 – Allowed values for the SEcod field . 61
Table A.8 – Transformation for the SPcod and SPcoc parameters when Dc≠0. 61
vii
Rec. ITU-T T.816 (V1) (02/2023)
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ISO/IEC 15444-17:2023 (E)
List of Figures
Page
Figure 1 – Arc arrangements within a single 2-span. A 𝟐×𝟐 cell is shown here with solid grid-points.
See Figure 2 for other geometric relationships between cells and 2-spans . 5
Figure 2 – Cell-span geometry for each of the four possible code-block anchor points . 5
Figure 3 – Root arc (dotted lines) and non-root arcs (solid lines). 8
Figure 4 – Possible break locations (tick-points) at the finest resolution, with 𝑭𝑩=𝟐, shown for the QuadBPT case.
Also shows the mapping of vertices with precision 𝑷𝒃 to tick-points . 9
Figure 5 – Stages of the breakpoint dependent inverse discrete wavelet transform . 10
Figure 6 – Interleaving of sub-band coefficients to a triangular grid for a given resolution r . 12
Figure 7 – Update step examples for TriBPT-LR arrangement . 12
Figure 8 – Predict step examples for a horizontal arc . 12
Figure 9 – Example of direct induction of a breakpoint . 14
Figure 10 – Example illustrating spatially induced breaks . 14
Figure 11 – Example of a spatially induced breakpoint on a non-root arc for the TriBPT-LR arrangement. 15
Figure 12 – Examples showing base-arc 𝒃𝒔𝒂 and gradients 𝑮𝒃𝒔𝒂 and 𝑮𝒘𝒅𝒈 along with corresponding binary flags
ORN and 𝑫𝑹𝑪𝑻𝑵𝑿_𝑭𝑳𝑨𝑮 𝒊𝒏𝒅𝒖𝒄𝒆𝒅 for root arcs . 16
Figure 13 – Example showing base-arc 𝒃𝒔𝒂 and gradients 𝑮𝒃𝒔𝒂 and 𝑮𝒘𝒅𝒈 along with corresponding binary flags
ORN and 𝑫𝑹𝑪𝑻𝑵𝑿_𝑭𝑳𝑨𝑮 𝒊𝒏𝒅𝒖𝒄𝒆𝒅 for diagonal non-root arc containing a spatially induced break . 16
Figure 14 – Examples of arcs 𝒑𝒓𝒍 parallel in orientation to root arcs centred at 𝒑 and containing a spatially induced
break. Gradient calculated across arc 𝒑𝒓𝒍 is denoted as 𝑮𝒑𝒓𝒍 . 19
Figure 15 – Example of arc 𝒑𝒓𝒍 parallel to the non-root arc centred and at 𝒑 and containing a spatially induced break.
Corresponding gradient across arc 𝒑𝒓𝒍 is shown as 𝑮𝒑𝒓𝒍 . 19
Figure 16 – Algorithm for determining the gradient 𝑮𝒃 based on validity flags VALID_WDG and VALID_PRL
and corresponding attributes . 20
Figure 17 – Parent 4-span arrangement at resolution 𝒓𝒓𝒕=𝒓−𝟏 for arc 𝒂 at resolution 𝒓 and centred at 𝒑 . 21
Figure 18 – Algorithm for determining the gradient 𝑮𝒃 for the reversible transform, based on validity flags
VALID_WDG and VALID_PRL and corresponding attributes . 23
Figure 19 – Interleaving of sub-band coefficients to a quadrilateral grid for a given resolution r . 23
Figure 20 – Phase 1 update step for (even, even) location 𝟐𝒏,𝟐𝒎 . 24
Figure 21 – Phase 1 update step for (even, odd) location 𝟐𝒏,𝟐𝒎+𝟏 and (odd, even) location 𝟐𝒏+𝟏,𝟐𝒎 . 25
Figure 22 – Phase 1 predict step for (odd, odd) location 𝟐𝒏+𝟏,𝟐𝒎+𝟏 with source locations of 𝑰𝒄,𝒓∗shown . 26
Figure 23 – Phase 2 update step for (even, even) location 𝟐𝒏,𝟐𝒎 . 27
Figure 24 – Phase 2 predict step examples . 28
Figure 25 – Canonical scanning pattern used for the significance coding passes of CL band code-blocks in a
QuadBPT component. In this case, missing cells within a 𝟐×𝟐 group are not included in the scan . 30
Figure 26 – Canonical scanning pattern used for the significance coding passes of CL band code-blocks in TriLR
components. Arcs belonging to cells that lie beyond the code-block boundaries are included in the significance
coding passes . 31
Figure 27 – Canonical scanning pattern used for the significance coding passes of CL band code-blocks in TriRL
components. Arcs belonging to cells that lie beyond the code-block boundaries are included in the significance
coding passes . 31
Figure 28 – Neighbouring cells and arcs involved in forming coding contexts for QuadBPT significance
decoding in CL band code-blocks . 34
Figure 29 – Neighbouring cells and arcs involved in forming coding contexts for TriLR significance
decoding in CL band code-blocks . 39
viii Rec. ITU-T T.816 (V1) (02/2023)
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ISO/IEC 15444-17:2023 (E)
Page
Figure 30 – Neighbouring cells and arcs involved in forming coding contexts for TriRL significance
decoding in CL band code-blocks . 40
Figure 31 – Breakpoint synthesis stages . 47
Figure 32 – Relationship between non-root and parent arcs during direct induction in synthesis stage 𝒓,
shown for the case of horizontal arcs. 48
Figure 33 – Rounding policies used in QuadBPT spatial induction, showing different induction examples
in three of the four 2-spans within a 4-span . 50
...
FINAL
INTERNATIONAL ISO/IEC
DRAFT
STANDARD FDIS
15444-17
ISO/IEC JTC 1/SC 29
Information technology — JPEG 2000
Secretariat: JISC
image coding system —
Voting begins on:
2022-07-29
Part 17:
Voting terminates on:
Extensions for coding of discontinuous
2022-09-23
media
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LOGICAL, COMMERCIAL AND USER PURPOSES,
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ISO/IEC FDIS 15444-17:2022(E)
FINAL
INTERNATIONAL ISO/IEC
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STANDARD FDIS
15444-17
ISO/IEC JTC 1/SC 29
Information technology — JPEG 2000
Secretariat: JISC
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Voting begins on:
Part 17:
Voting terminates on:
Extensions for coding of discontinuous
media
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ii
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ISO/IEC 15444-17:2022(E)
Contents
Foreword . v
Introduction . vi
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviated terms . 9
5 Conformance . 9
5.1 Part-17 codestream . 9
5.2 Part-17 decoder . 9
6 Breakpoint component structure . 10
6.1 Breakpoint components and the reference grid . 10
6.2 Division of breakpoint resolutions into cells, arcs and the CL band . 11
6.3 Division of breakpoint resolutions into precincts and code-blocks . 12
6.4 Root and non-root arc breakpoint associations . 14
6.5 Breakpoint values and vertices . 15
7 Breakpoint-dependent spatial wavelet transformation . 17
7.1 Overview . 17
7.2 TriBPT-dependent irreversible transforms . 19
7.2.1 Introduction . 19
7.2.2 Arcs with 𝐭𝐛=𝟎 . 20
7.2.3 Arcs with 𝐭𝐛=𝟑 . 21
7.2.4 Arcs with 𝐭𝐛=𝟐 . 21
7.2.5 Arcs with 𝐭𝐛=𝟏 . 26
7.3 TriBPT-dependent reversible transforms . 33
7.3.1 Arcs with 𝐭𝐛=𝟎 . 33
7.3.2 Arcs with 𝐭𝐛=𝟑 . 33
7.3.3 Arcs with 𝐭𝐛=𝟐 . 34
7.3.4 Arcs with 𝐭𝐛=𝟏 . 34
7.4 QuadBPT-dependent transforms . 34
7.4.1 Introduction . 34
7.4.2 BD_2D_SR phase 1 . 35
7.4.3 BD_2D_SR phase 2 . 38
8 Decoding of breakpoint code-blocks . 40
8.1 Embedded bit-plane decoding of breakpoints . 40
8.2 Inter-band coding mode (BPT_INTER) . 42
8.3 Cell-based scanning patterns and CBAP-based block flipping . 42
8.4 QuadBPT decoding procedures . 45
8.4.1 MQ Coder contexts and initial states for QuadBPT decoding . 45
8.4.2 Derivation of context labels for QuadBPT CL band significance coding passes . 46
8.4.3 Non-root significance decoding for QuadBPT CL code-blocks . 48
8.4.4 Root significance decoding for QuadBPT CL code-blocks . 49
8.4.5 Root significance decoding for QuadBPT LL code-blocks . 50
8.4.6 Position refinement decoding for QuadBPT code-blocks . 51
8.5 TriBPT decoding procedures . 51
8.5.1 MQ Coder contexts and initial states for TriBPT decoding . 51
8.5.2 Derivation of context labels for TriBPT CL band significance coding passes . 52
8.5.3 Non-root significance decoding for TriBPT CL code-blocks . 55
8.5.4 Root significance decoding for TriBPT CL code-blocks . 57
8.5.5 Root significance decoding for TriBPT LL code-blocks . 59
8.5.6 Position refinement decoding for TriBPT code-blocks . 60
8.6 Quality layers and packets for breakpoint components . 60
© ISO/IEC 2022 – All rights reserved
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ISO/IEC 15444-17:2022(E)
9 Reconstruction of breakpoint components . 62
9.1 Overview . 62
9.2 Direct induction step . 63
9.2.1 Introduction . 63
9.2.2 Extrapolation Qualifier for TriBPT direct induction . 64
9.3 QuadBPT spatial induction . 64
9.3.1 Introduction . 64
9.3.2 Image boundary handling for QuadBPT . 66
9.4 TriBPT spatial induction . 66
9.4.1 TriBPT induction modes and corner notation . 66
9.4.2 4-arc mode . 68
9.4.3 3-arc mode . 70
9.4.4 Extrapolation qualifier for TriBPT spatial induction . 71
9.4.5 Rounding policies for TriBPT spatial induction . 73
9.4.6 Image boundary handling for TriBPT . 73
(normative) Part-17 Codestream syntax . 75
A.1 General . 75
A.2 SIZ marker segment . 75
A.3 CAP marker segment . 75
A.4 Hierarchical Data Type (HDT) marker segment . 76
A.5 COD and COC marker segments . 77
(informative) Hierarchical breakpoint encapsulation and raw file format . 80
B.1 General . 80
B.2 Raster organization of breakpoints . 80
B.3 16- and 32-bit packed breakpoint values . 81
B.4 A raw file format for breakpoints . 83
iv
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ISO/IEC 15444-17:2022(E)
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.
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 https://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 ITU-T (as ITU-T - T.816) and drafted in accordance with its editorial
rules, in collaboration with Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO/IEC 15444 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.
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ISO/IEC 15444-17:2022(E)
Introduction
JPEG 2000 Parts 1 and 2 provide a suite of scalable coding technologies that are particularly suitable for
photographic media, but less effective at coding media with hard discontinuities. An important example
of such media is depth imagery, where each image sample is related to the length of the 3D line segment
between the corresponding scene point and the camera. Depth imagery includes stereo disparity maps,
where sample values are reciprocally related to depth. Another example of media with strong
discontinuities is optical flow data, where each sample location is a two-dimensional vector. In these
examples, discontinuities arise naturally at the boundaries of scene objects. Moreover, where this
happens, intermediate values that might be obtained by bandlimited image resampling or interpolation
operations have no physical meaning – i.e., they do not correspond to the depth or flow vector of any
object in the original scene. The Discrete Wavelet Transform (DWT) employed in JPEG 2000 is not well
suited to the coding of such media, both from the perspective of coding efficiency and considering the
nature of distortions that result when the wavelet subband samples are quantized.
To address these challenges, this Recommendation | International Standard introduces alternate
“breakpoint-dependent” spatial wavelet transforms that dependent on an auxiliary image component,
known as a “breakpoint component.” This Recommendation | International Standard also introduces
scalable coding technologies for breakpoint components. Any non-initial component or components
within the codestream can be designated as breakpoint components, allowing them to be used as the
source of breakpoints for other components, or tiles thereof, which specify the use of breakpoint-
dependent wavelet transforms.
This Recommendation | International Standard specifies two different types of breakpoint components,
designated as “QuadBPT” and “TriBPT” components, with associated decoding and synthesis tools.
Associated with the type of breakpoint component is a corresponding breakpoint-dependent wavelet
transform, with its synthesis tools. The reconstruction procedures described in this document produce
individual sample values. In the TriBPT case, it is possible instead to directly reconstruct a deformable
triangular mesh, whose complexity is related to the number of non-zero wavelet coefficients and the
number of decoded breaks, which are identified here as “vertices.” In each case, breakpoints introduce
tears in the mesh. This feature can be valuable in computer graphics applications, where the mesh
elements provide a more convenient description of the data than individual samples.
The normative material of this Recommendation | International Standard is contained within the main
body together with Annex A. Additionally, Annex B describes ways of encapsulating breakpoint data
within a linear file structure, that can be used as a source for encoding and a target for decoding
procedures.
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ISO/IEC 15444-17:2022(E)
Information technology — JPEG 2000 image coding system —
Part 17: Extensions for coding of discontinuous media
1 Scope
This Recommendation | International Standard defines QuadBPT and TriBPT image components,
collectively known as “breakpoint components,” and specifies decoding and reconstruction procedures
for recovering breakpoint component sample values from the codestream. This Recommendation |
International Standard also specifies “breakpoint-dependent” spatial wavelet transforms that can be
used in place of the transforms specified in Recommendation ITU-T T.800 | ISO/IEC 15444-1, for selected
image components or tile-components. Extensions to the codestream syntax of Rec. ITU-T T.800 |
ISO/IEC 15444-1 are specified to enable the identification of breakpoint components, of components that
can use a breakpoint-dependent spatial wavelet transform, and the association of breakpoint
components with such breakpoint-dependent wavelet transforms.
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.
Recommendation ITU-T T.800 | ISO/IEC 15444-1, Information technology — JPEG 2000 image coding
system — Part 1: Core coding system.
Recommendation ITU-T T.801 | ISO/IEC 15444-2, Information technology — JPEG 2000 image coding
system: Extensions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in Rec. ITU-T T.800 | ISO/IEC 15444-
1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
2-span
square configuration of width 2 and height 2, with 9 grid-points, such that the four corner grid-points all
have coordinates that are divisible by 2
3.2
4-span
2×2 configuration of 2-spans (3.1), involving 25 grid-points, such that the four corner grid-points all
have coordinates that are divisible by 4
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ISO/IEC 15444-17:2022(E)
3.3
arc
line segment connecting grid-points with even valued coordinates at any resolution of a breakpoint tile-
component
3.4
ambivalent break
induced break (3.5) that has insufficient precision to determine whether the break occurs in the first or
second half of the arc
3.5
break
explicitly decoded or inferred location within an arc (3.3) that indicates a boundary within an image
component
Note 1 to entry: Breaks modify the behaviour of breakpoint-dependent transforms on that other image component.
Note 2 to entry: An arc has at most one break.
3.6
breakpoint
data structure consisting of break type, location and precision information for an arc (3.3)
Note to entry: Type-0 breakpoints have no break at all.
3.7
breakpoint tile-component
all the breakpoints of a given tile, within a breakpoint component (3.8)
3.8
breakpoint component
JPEG 2000 codestream image component that represents arc breakpoint (3.6) information
3.9
cell
2×2 configuration of grid-points within a resolution of a breakpoint tile-component (3.7)
Note to entry: Cells belong to a well-defined partition that is anchored at the global code-block anchor point.
3.10
CL Band
the sole subband associated with each resolution of a breakpoint tile-component (3.7) other than the
lowest resolution
3.11
code-block anchor point
origin of the coding partitions, which is one of the locations (0,0), (0,1), (1,0) or (1,1)
[SOURCE: Rec. ITU-T T.801 | ISO/IEC 15444-2]
3.12
directly induced break
break (3.5) on an arc that is inferred from a break on a parent arc
3.13
extrapolation qualifier
2-bit quantity 𝑒 which controls the way gradients are obtained for extrapolation within a TriBPT-
�
dependent transformation
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ISO/IEC 15444-17:2022(E)
3.14
indefinite break
induced break (3.15) on an arc that is derived from one or more ambivalent breaks (3.4), such that there
is insufficient precision to determine whether any break at all exists on the arc
3.15
induced break
break (3.5) on an arc that is inferred from breaks on other arcs
3.16
induction block
condition on an arc (3.3) that is explicitly recovered from the decoding of breakpoint code-blocks,
indicating that no break (3.5) shall be induced on that arc
3.17
non-root arc
arc (3.3) that is not a root arc
3.18
parent arc
arc (3.3) at depth 𝑑+1 in the breakpoint decomposition that contains an arc at depth 𝑑
Note to entry: At most two arcs at depth 𝑑 can have the same parent at depth 𝑑+1.
3.19
pass-complete
code-block within a breakpoint component for which one or more coding passes are found within the
codestream packets and the last such coding pass is identified as completing the code-block’s
representation via the packet header signalling mechanisms
3.20
QuadBPT
breakpoint (3.6) arrangement involving only horizontal and vertical arcs (3.3)
3.21
root arc
arc (3.3) that is not contained within any arc projected from the next lower resolution of a breakpoint
tile-component (3.7), regardless of whether that next lower resolution actually exists within the tile-
component’s resolution hierarchy
3.22
spatially induced break
induced break (3.15) that is inferred from breaks on non-parent arcs
3.23
tick-point
possible break (3.5) location along an arc
3.24
TriBPT
breakpoint (3.6) arrangement involving horizontal, vertical and diagonal arcs (3.3)
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ISO/IEC 15444-17:2022(E)
3.25
TriBPT-LR
TriBPT (3.24) breakpoint arrangement involving diagonal arcs that run from the top-left to the bottom-
right of a 2-span within any resolution of a breakpoint tile-component (3.7)
3.26
TriBPT-RL
TriBPT (3.24) breakpoint arrangement involving diagonal arcs that run from the top-right to the bottom-
left of a 2-span within any resolution of a breakpoint tile-component (3.7)
3.27
vertex
explicitly coded break (3.5) location
3.28
zero-complete
code-block within a breakpoint component (3.8) that makes no contribution to any codestream packet
and is identified as complete by the first packet header of its precinct
4 Symbols and abbreviated terms
• CBAP (𝒛 ,𝒛 ) – code-block anchor point
𝒙 𝒚
• MAX_WDG – maximum search distance for the gradient extrapolation algorithm used during the
TriBPT-dependent prediction step associated with a spatially induced arc.
• BPT_INTER – binary flag that is 1 if code-blocks of a breakpoint component use the inter-band
coding mode and 0 if the code-blocks of a breakpoint component are coded without reference to
any other code-block data.
5 Conformance
5.1 Part-17 codestream
A Part-17 Codestream shall conform to Annex A.
5.2 Part-17 decoder
A Part-17 Decoder shall process a Part-17 codestream as specified in Rec. ITU-T T.800 | ISO/IEC 15444-
1 together with any additional signalled capability, with the exception of breakpoint components and tile-
components that identify the use of a breakpoint-dependent spatial wavelet transform, in which case the
following shall apply:
§ breakpoint components shall have the structure specified in Clause 6;
§ tile-components that use a breakpoint-dependent spatial wavelet transform shall be processed
in accordance with Clause 7; and
§ breakpoint components shall be reconstructed from breakpoint code-blocks in accordance with
Clause 0, where breakpoint code-blocks are decoded in accordance with Clause 8.
This Recommendation | International Standard is compatible with the coding technologies specified in
both Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801 | ISO/IEC 15444-2. However:
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ISO/IEC 15444-17:2022(E)
1. Breakpoint components, as specified herein, are not compatible with the multiple component
transformations specified in Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801 | ISO/IEC
15444-2, nor are they compatible with the non-linear transformations specified in Rec. ITU-T
T.801 | ISO/IEC 15444-2; and
2. Breakpoint code-blocks, as specified herein, are not compatible with the region of interest coding
and extraction techniques specified in Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801
| ISO/IEC 15444-2.
6 Breakpoint component structure
6.1 Breakpoint components and the reference grid
Breakpoint components have a “hierarchical data type,” meaning that they are described at multiple
resolutions, in a dyadic hierarchy. Breakpoint components are identified via the HDT marker segment
c
defined in A.4. In particular, component 𝑐 is a breakp oint component if Ihdt lies in the range 1 to 3.
Breakpoint component 𝑐 is defined with respect to the same reference grid as other JPEG 2000
components, in terms of the global image dimensions (Xsiz, Ysiz), image offset (XOsiz, YOsiz) and
� �
sampling factors (𝑋Rsiz ,𝑌Rsiz ) that are recorded in the SIZ marker segment. The grid-points of
component 𝑐 consist of all integer coordinates in the rectangle with upper left hand corner at (𝑥 ,𝑦 ) and
� �
lower right hand corner at (𝑥 −1,𝑦 −1), where
� �
XOsiz Xsiz
...
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