ISO/IEC 10918-6:2013

INTERNATIONAL ISO/IEC
STANDARD 10918-6
First edition
2013-04-15
Information technology — Digital
compression and coding of continuous-
tone still images: Application to printing
systems
Technologies de l'information — Compression numérique et codage
des images fixes à modelé continu: Application aux systèmes
d'impression
Reference number
©
ISO/IEC 2013
©  ISO/IEC 2013
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ii © ISO/IEC 2013 – 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. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 10918-6 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, in collaboration with
ITU-T. The identical text is published as Rec. ITU-T T.872 (06/2012).
ISO/IEC 10918 consists of the following parts, under the general title Information technology -- Digital
compression and coding of continuous-tone still images:
 Part 1: Requirements and guidelines
 Part 2: Compliance testing
 Part 3: Extensions
 Part 4: Registration of JPEG profiles, SPIFF profiles, SPIFF tags, SPIFF colour spaces, APPn markers,
SPIFF compression types and Registration Authorities (REGAUT)
 Part 5: JPEG File Interchange Format (JFIF)
 Part 6: Application to printing systems

© ISO/IEC 2013 – All rights reserved iii

CONTENTS
Page
1 Scope . 1
2 Normative references . 1
3 Definitions . 1
4 Abbreviations . 2
5 Conformance . 2
6 JPEG print-application support overview . 2
6.1 Colour encodings and associated values to define white and black . 2
6.2 Characterization of colour or grayscale values . 3
6.3 Order of components for images encoded with three or four components . 3
6.4 Start of Frame (SOF) markers . 3
6.5 Application markers and marker segments . 3
7 Conversions between colour encodings . 4
Bibliography . 5
iv © ISO/IEC 2013 – All rights reserved

Introduction
This Recommendation | International Standard specifies a subset of features and application tools for the interchange of

images encoded according to the JPEG image coding standard (Rec. ITU-T T.81 | ISO/IEC 10918-1) for printing.

© ISO/IEC 2013 – All rights reserved v

INTERNATIONAL STANDARD
RECOMMENDATION ITU-T
Information technology – Digital compression and coding of
continuous-tone still images: Application to printing systems
1 Scope
This Recommendation | International Standard specifies a subset of features and application tools for printing
applications that encode or decode images based on JPEG (Recommendation ITU-T T.81 | ISO/IEC 10918-1) encoding.
Its creation was proposed by members of the digital printing industry to ensure that applications developed for printing
systems can exchange JPEG images.
2 Normative references
The following Recommendations and International Standards contain provisions which, through reference in this text,
constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated
were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this
Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent
edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently
valid International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently
valid ITU-T Recommendations.
– Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994, Information technology – Digital
compression and coding of continuous-tone still images – Requirements and guidelines.
– Recommendation ITU-T T.871 (2011) | ISO/IEC 10918-5:2011, Information technology – Digital
compression and coding of continuous-tone still images – JPEG File Interchange Format (JFIF).
– Recommendation ITU-R BT.601-6 (2007), Studio encoding parameters of digital television for
standard 4:3 and wide screen 16:9 aspect ratios.
– ISO 15076-1:2010, Image technology colour management – Architecture, profile format and data
structure – Part 1: Based on ICC.1:2004-10.
3 Definitions
For the purposes of this Recommendation | International Standard, the following definitions apply:
3.1 CMYK: 32-bit four-colour channel encoding in which the first channel consists of an eight-bit value for
Cyan, the second channel consists of an eight-bit value for Magenta, the third channel consists of an eight-bit value for
Yellow, and the fourth channel consists of an eight-bit value for Key (black); in the absence of appropriate metadata,
the interpretation of these values is device dependent.
3.2 complement: Subtract from 255.
3.3 grayscale: Eight-bit single channel encoding in which the value is monochromatic, e.g., describes the
intensity of light varying from white to black or from black to white.
3.4 ICC Profile: Set of data that characterizes the input or output values of a colour device, e.g., as specified in
ISO 15076-1.
3.5 JPEG File Interchange Format (JFIF): The interchange format specified in Rec. ITU-T T.871 |
ISO/IEC 10918-5 having 1 or 3 colour channels and 8 bits per colour channel.
3.6 RGB: 24-bit three-colour channel encoding in which the first channel consists of an eight-bit value for Red,
the second channel consists of an eight-bit value for Green, and the third channel consists of an eight-bit value for Blue;
in the absence of appropriate metadata, the interpretation of these values is device dependent.
Rec. ITU-T T.872 (06/2012) 1
4 Abbreviations
For the purposes of this Recommendation | International Standard, the following abbreviations apply:
Ap Byte i of application data (specified in Rec. ITU-T T.81 | ISO/IEC 10918-1)
i
APP Application data marker, type 2 (specified in Rec. ITU-T T.81 | ISO/IEC 10918-1)
APP Application data marker, type 14 (specified in Rec. ITU-T T.81 | ISO/IEC 10918-1)
CMYK Cyan, Magenta, Yellow, and Key (black) colour component values
DNL Define Number of Lines (specified in Rec. ITU-T T.81 | ISO/IEC 10918-1)
EOI End o
...