ISO/IEC 18477-5:2018

INTERNATIONAL ISO/IEC
STANDARD 18477-5
First edition
2018-03
Information technology — Scalable
compression and coding of
continuous-tone still images —
Part 5:
Reference software
Technologies de l'information — Compression échelonnable et codage
d'images plates en ton continu —
Partie 5: Logiciel de référence
Reference number
©
ISO/IEC 2018
© ISO/IEC 2018
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2018 – 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 Conformance language . 2
5.2 Typesetting . 3
6 Reference software . 3
6.1 Purpose . 3
6.2 Examples of use . 3
6.3 General . 4
Annex A (informative) Unpacking and compiling the reference software for
ISO/IEC 18477-3 and ISO/IEC 18477-6 to ISO/IEC 18477-9 . 5
Annex B (informative) Using the reference software for ISO/IEC 18477-3 and
ISO/IEC 18477-6 to ISO/IEC 18477-9 . 6
Annex C (informative) Unpacking and compiling the reference software for
ISO/IEC 18477-7 profile B.12
Annex D (informative) Using the reference software for ISO/IEC 18477-7 profile B .13
Bibliography .17
© ISO/IEC 2018 – All rights reserved iii

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. In the field of information technology, ISO and IEC have established a joint technical committee,
ISO/IEC JTC 1.
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).
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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by 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 18477 series can be found on the ISO website.
iv © ISO/IEC 2018 – All rights reserved

Introduction
ISO/IEC 18477, also known under the name "JPEG XT", is a series of extensions of ISO/IEC 18477-
1, a compression system for continuous tone digital still images which is backwards compatible
with Rec. ITU-T T.81 | ISO/IEC 10918-1. That is, legacy applications conforming to Rec. ITU-T T.81 |
ISO/IEC 10918-1 will be able to reconstruct streams generated by an encoder conforming to the
ISO/IEC 18477 series, though will possibly not be able to reconstruct such streams in full dynamic
range, full quality or other features defined in the ISO/IEC 18477 series.
This document offers implementations of various parts of the ISO/IEC 18477 standard that demonstrate
the features and capabilities of JPEG XT. Its purpose is to act as a guideline for implementations and
as a reference for conformance testing. As such, the implementations are conforming to the part of
Rec. ITU-T T.81 | ISO/IEC 10918-1 that has been standardized as ISO/IEC 18477-1, i.e. it implements the
baseline, extended sequential and progressive Huffman coding modes of the legacy standard together
with common extensions such as Rec. ITU-T T.871 | ISO/IEC 10918-5, commonly known as JFIF. In
addition, the reference software implementations also cover all other parts of the ISO/IEC 18477
standard, i.e., IDR coding, HDR coding, lossless and near-lossless coding and coding of alpha channels.
This document includes the source code for reference implementations of the ISO/IEC 18477 series of
standards, available at http:// standards .iso .org/ iso -iec/ 18477/ -5/ ed -1/ en. They have been successfully
1) 2)
TM
complied and tested on Linux and Windows operating systems at the time of writing.
Note that ISO/IEC 18477-1 does not include the arithmetic coding modes, the hierarchical coding modes
and the lossless coding modes of Rec. ITU-T T.81 | ISO/IEC 10918-1.
1) Linux is an example of a suitable product available commercially. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO or IEC of this product.
2) Windows is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO or IEC of this product.
© ISO/IEC 2018 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 18477-5:2018(E)
Information technology — Scalable compression and
coding of continuous-tone still images —
Part 5:
Reference software
1 Scope
This document provides reference implementations of multiple parts of the ISO/IEC 18477 series, also
known under the name "JPEG XT". JPEG XT is designed primarily for compression of continuous-tone
photographic content.
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/IEC 18477-1, Information technology — Scalable compression and coding of continuous-tone still
images — Part 1: Scalable compression and coding of continuous-tone still images
ISO/IEC 18477-3, Information technology — Scalable compression and coding of continuous-tone still
images — Part 3: Box file format
ISO/IEC 18477-6, Information technology — Scalable compression and coding of continuous-tone still
images — Part 6: IDR Integer Coding
ISO/IEC 18477-7, Information technology — Scalable compression and coding of continuous-tone still
images — Part 7: HDR Floating-Point Coding
ISO/IEC 18477-8, Information technology — Scalable compression and coding of continuous-tone still
images — Part 8: Lossless and near-lossless coding
ISO/IEC 18477-9, Information technology — Scalable compression and coding of continuous-tone still
images — Part 9: Alpha channel coding
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
codestream
sequence of bytes that conforms to or is to be checked for conformance with the codestream syntax
specified in ISO/IEC 18477-1 and/or ISO/IEC 18477-3
© ISO/IEC 2018 – All rights reserved 1

3.2
decoder
embodiment of the decoding process specified in the ISO/IEC 18477 series or a process embodiment
that is to be tested for conformance to the ISO/IEC 18477 series
3.3
encoder
process that produces codestreams (3.1) that conform to ISO/IEC 18477-1 or ISO/IEC 18477-3 or that
are to be tested for conformance to the ISO/IEC 18477 series
3.4
pfm format
format similar to ppm (3.6) for carrying floating-point based colour images
Note 1 to entry: It is further specified in ISO/IEC 18477-4.
3.5
pnm format
superset of the pfm (3.4) and ppm format (3.6)
3.6
ppm format
portable pixmap format for carrying three-component integer sample based colour images specified in
ISO/IEC 18477-4
4 Abbreviated terms
HDR high dynamic range
IDR intermediate dynamic range
LDR low dynamic range
PPM portable pixmap format
PFM portable floating-point format
TMO tone mapping operator
5 Conventions
5.1 Conformance language
This document consists of normative and informative text.
Normative text is that text which expresses mandatory requirements. The word "shall" is used to
express mandatory requirements strictly to be followed in order to conform to this document and
from which no deviation is permitted. A conforming implementation is one that fulfils all mandatory
requirements.
Informative text is text that is potentially helpful to the user, but not indispensable and can be removed,
changed or added editorially without affecting interoperability. All text in document is normative,
with the following exceptions: the Introduction, any parts of the text that are explicitly labelled as
"informative" and statements appearing with the preamble "NOTE" and behaviour described using the
word "should". The word "should" is used to describe behaviour that is encouraged but is not required
for conformance to this document.
The keywords "may" and "need not" indicate a course of action that is permissible in a conforming
implementation.
2 © ISO/IEC 2018 – All rights reserved

The keyword "reserved" indicates a provision that is not specified at this time, shall not be used and
may be specified in the future. The keyword "forbidden" indicates "reserved" and in addition indicates
that the provision will never be specified in the future.
5.2 Typesetting
Regular face fonts as this text describe informative text that provides instructions, comments or details
for the reader.
Monospaced text as this paragraph indicates program input or output as necessary to either
run the software or as generated by the software on the console.
6 Reference software
6.1 Purp
...