ISO/IEC 15444-6:2013

Information technology - JPEG 2000 image coding system - Part 6: Compound image file format

This Recommendation | International Standard defines a normative but optional file format for storing compound images using the JPEG 2000 file format family architecture. This format is an extension of the JP2 file format defined in Rec. ITU-T T.800 | ISO/IEC 15444-1 Annex I and uses boxes defined for both the JP2 file format and the JPX file format defined in Rec. ITU-T T.801 | ISO/IEC 15444-2 Annex M. This Recommendation | International Standard is useful for applications storing multiple pages, images with mixed content, and/or images that need more structure than provided in JP2. Applications that implement this file format shall implement it as described in this Recommendation | International Standard. This Recommendation | International Standard: ? specifies a binary container for multiple bi-level and continuous-tone images used to represent a compound image; ? specifies a mechanism by which multiple images can be combined into a single compound image, based on the mixed raster content (MRC) model; ? specifies a mechanism for grouping multiple images in a hierarchy of layout objects, pages and page collections; ? specifies a mechanism for storing JPEG 2000 and other compressed image data formats; ? specifies a mechanism by which metadata can be included in files specified by this Recommendation | International Standard.

Technologies de l'information — Système de codage d'images JPEG 2000 — Partie 6: Format de fichier d'image de composant

General Information

• Status: Published
• Publication Date: 14-Jul-2013
• ICS: 35.040 - Information coding
• ICS: 35.040.30 - Coding of graphical and photographical information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29/WG 1 - JPEG Coding of digital representations of images
• Current Stage: 9060 - Close of review
• Completion Date: 02-Sep-2029

Relations

• Revises: ISO/IEC 15444-6:2003/Amd 1:2007 - Information technology - JPEG 2000 image coding system - Part 6: Compound image file format - Amendment 1: Hidden text metadata
• Effective Date: 10-Dec-2011
• Revises: ISO/IEC 15444-6:2003 - Information technology - JPEG 2000 image coding system - Part 6: Compound image file format
• Effective Date: 10-Dec-2011

Overview

ISO/IEC 15444-6:2013 specifies the Compound Image File Format within the JPEG 2000 family. This normative (but optional) file format extends the JP2/JPX architecture to provide a binary container for compound images - combining multiple bi-level and continuous-tone images, layout structures, and metadata. The 2013 second edition consolidates the original 2003 standard and its 2007 amendment.

Keywords: ISO/IEC 15444-6, JPEG 2000, compound image file format, JP2, JPX, mixed raster content (MRC)

Key topics and technical requirements

• Mixed Raster Content (MRC) model: defines how multiple image layers (e.g., text mask + foreground + background) are combined to form a single compound image.
• Binary container for multiple images: supports storage of multi-page documents, layout objects, and page collections using the JPEG 2000 file family architecture.
• Integration with JP2/JPX boxes: uses box structures defined in JP2 (ISO/IEC 15444-1) and JPX (ISO/IEC 15444-2) for flexible object and metadata packaging.
• Support for compressed image formats: specifies mechanisms to store JPEG 2000 codestreams and other compressed image data types within the compound container.
• Metadata and hidden text: defines mechanisms for embedding metadata, intellectual property information, annotations, and hidden text (searchable or accessible text layers).
• Structure and profiles: includes hierarchical grouping (layout objects → pages → page collections), box definitions, profiles and decompression guidelines to ensure interoperable implementations.
• Normative implementation: applications implementing the format shall follow the standard’s descriptions and requirements.

Keywords: MRC, metadata, JP2 boxes, JPX, multi-page images, hidden text

Applications and who uses it

ISO/IEC 15444-6 is targeted at organizations and developers needing structured, high-quality image containers:

• Digital libraries and archives (multi-page scanned documents, mixed content pages)
• Document imaging and capture vendors (scanners, OCR workflows)
• Enterprise content management (ECM) and records management systems
• Publishers and print-on-demand services handling pages with mixed raster/text layers
• Software developers building viewers, converters, or repositories that support JPEG 2000 compound files

Practical benefits include efficient storage of layered/mixed-content pages, improved preservation of layout and text, and standardized metadata handling for long-term access and interoperability.

Keywords: multi-page, document imaging, digital preservation, OCR, ECM

Related standards

• ISO/IEC 15444-1 (JP2 core file format)
• ISO/IEC 15444-2 (JPX extensions)
• Related MRC and image compression standards referenced in ISO/IEC 15444-6

Keywords: ISO/IEC 15444, JP2, JPX, MRC

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 15444-6
Second edition
2013-07-15
Information technology — JPEG 2000
image coding system —
Part 6:
Compound image file format
Technologies de l'information — Système de codage d'images
JPEG 2000 —
Partie 6: Format de fichier d'image de composant

Reference number
©
ISO/IEC 2013
©  ISO/IEC 2013
All rights reserved. Unless otherwise specified, 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.
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© ISO/IEC 2013 – All rights reserved

ii
CONTENTS
Page
1 Scope . 1
2 Normative references . 1
2.1 Identical Recommendations | International Standards . 1
2.2 ITU, IEC and ISO references . 2
2.3 Additional references . 2
3 Definitions . 3
4 Abbreviations . 4
5 General arrangement . 4
5.1 Mixed raster content model . 5
5.2 File elements and structure . 6
5.3 Hidden text metadata . 14
5.4 JPM use scenarios . 15
Annex A – Compound image file structure . 18
A.1 File identification . 18
A.2 File organization. 18
A.3 Box definition . 20
A.4 Boxes used in a compound image file . 20
Annex B – Box definitions . 23
B.1 File level boxes . 23
B.2 Page level boxes . 29
B.3 Layout object level boxes . 31
B.4 Object level boxes . 33
B.5 JP2 codestream element boxes . 36
B.6 General/common boxes . 37
Annex C – Metadata . 49
C.1 Adding intellectual property rights information in JPM . 49
C.2 Adding vendor specific information to the JPM file format . 49
Annex D – Profiles . 50
D.1 JPM profiles . 50
D.2 Decompression profiles . 51
Annex E . 52
Annex F – Hidden text and annotations storage . 53
F.1 Storage of HTX in JPM . 53
F.2 Compression of HTX . 53
Annex G – Hidden text and annotations types and elements . 54
G.1 Overview . 54
G.2 Types . 55
G.3 Common attributes . 56
G.4 Elements . 58
Annex H – Hidden text and annotations schema . 69
H.1 XML schema . 69
Annex I – Hidden text and annotations examples . 70
I.1 Example 1 . 70
I.2 Example 2 . 72
I.3 Example 3 . 72
Rec. ITU-T T.805 (01/2012) iii

Page
Annex J – Guidelines for constructing URLs for JPM files . 90
J.1 Pages and layout objects . 90
J.2 Metadata boxes . 90
J.3 Labels . 90
J.4 Page collections . 91
J.5 Page thumbnails . 91
J.6 Document thumbnail . 91
J.7 Byte ranges . 91

iv Rec. ITU-T T.805 (01/2012)
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 15444-6 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.805 (01/2012).
This second edition is a consolidation of the first edition (ISO/IEC 15444-6:2003) and
ISO/IEC 15444-6:2003/Amd.1:2007.
ISO/IEC 15444 consists of the following parts, under the general title Information technology — JPEG 2000 image
coding system:
– Part 1: Core coding system
– Part 2: Extensions
– Part 3: Motion JPEG 2000
– Part 4: Conformance testing
– Part 5: Reference software
– Part 6: Compound image file format
– Part 8: Secure JPEG 2000
– Part 9: Interactivity tools, APIs and protocols
– Part 10: Extensions for three-dimensional data
– Part 11: Wireless
– Part 12: ISO base media file format
– Part 13: An entry level JPEG 2000 encoder
– Part 14: XML structural representation and reference
Rec. ITU-T T.805 (01/2012) v
INTERNATIONAL STANDARD
RECOMMENDATION ITU-T
Information technology – JPEG 2000 image coding system:
Compound image file format
1 Scope
This Recommendation | International Standard defines a normative but optional file format for storing compound
images using the JPEG 2000 file format family architecture. This format is an extension of the JP2 file format defined
in Rec. ITU-T T.800 | ISO/IEC 15444-1 Annex I and uses boxes defined for both the JP2 file format and the JPX file
format defined in Rec. ITU-T T.801 | ISO/IEC 15444-2 Annex M. This Recommendation | International Standard is
useful for applications storing multiple pages, images with mixed content, and/or images that need more structure than
provided in JP2.
Applications that implement this file format shall implement it as described in this Recommendation | International
Standard. This Recommendation | International Standard:
– specifies a binary container for multiple bi-level and continuous-tone images used to represent a
compound image;
– specifies a mechanism by which multiple images can be combined into a single compound image, based
on the mixed raster content (MRC) model;
– specifies a mechanism for grouping multiple images in a hierarchy of layout objects, pages and page
collections;
– specifies a mechanism for storing JPEG 2000 and other compressed image data formats;
– specifies a mechanism by which metadata can be included in files specified by this Recommendation |
International Standard.
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.
2.1 Identical Recommendations | International Standards
– Recommendation ITU-T T.44 (1999) | ISO/IEC 16485/Amd 1:2000, Information technology – Mixed
Raster Content (MRC).
– Recommendation ITU-T T.44 Amd.1 (1999) | ISO/IEC 16485:2000 Amd 1, Accommodation of new
Annex B.
– Recommendation ITU-T T.45 (2000), Run-length Colour Encoding.
– Recommendation ITU-T T.50 (1992) | ISO/IEC 646:1991, International Reference Alphabet (IRA)
(Formerly International Alphabet No. 5 or IA5) – Information technology – 7-bit coded character set for
information interchange.
– 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.82 (1993) | ISO/IEC 11544:1993, Information technology – Coded
representation of picture and audio information – Progressive bi-level image compression.
– Recommendation ITU-T T.83 (1994) | ISO/IEC 10918-2:1995, Information technology – Digital
compression and coding of continuous-tone still images: Compliance testing.
– Recommendation ITU-T T.84 (1996) | ISO/IEC 10918-3:1997, Information technology – Digital
compression and coding of continuous-tone still images: Extensions.
Rec. ITU-T T.805 (01/2012) 1
– Recommendation ITU-T T.84 Amendment 1 (1999) | ISO/IEC 10918-3:1997/Amd 1:1999, Provisions to
allow registration of new compression types and versions in the SPIFF header.
– Recommendation ITU-T T.86 (1998) | ISO/IEC 10918-4:1999, Information technology – Digital
compression and coding of continuous-tone still images: Registration of JPEG Profiles, SPIFF Profiles,
SPIFF Tags, SPIFF colour Spaces, APPn Markers, SPIFF Compression types and Registration
authorities (REGAUT).
– Recommendation ITU-T T.87 (1998) | ISO/IEC 14495-1:2000, Information technology – Lossless and
near-lossless compression of continuous-tone still images – Baseline.
– Recommendation ITU-T T.88 (2000) | ISO/IEC 14492:2001, Information technology – Lossy/lossless
coding of bi-level images.
– Recommendation ITU-T T.800 (2002) | ISO/IEC 15444-1:2004, Information technology – JPEG 2000
image coding system: Core coding system.
– Recommendation ITU-T T.801 (2002) | ISO/IEC 15444-2:2004, Information technology – JPEG 2000
image coding system: Extensions.
– Recommendation ITU-T T.803 (2002) | ISO/IEC 15444-4:2004, Information technology – JPEG 2000
image coding system: Conformance testing.
2.2 ITU, IEC and ISO references
– Recommendation ITU-T T.4 (2003), Standardization of Group 3 facsimile terminals for document
transmission.
– Recommendation ITU-T T.6 (1988), Facsimile coding schemes and coding control functions for Group
4 facsimile apparatus.
– Recommendation ITU-T T.42 (2003), Continuous-tone colour representation method for facsimile.
– Recommendation ITU-T T.89 (2001), Application profiles for Recommendation T.88 – Lossy/lossless
coding of bi-level images (JBIG2) for facsimile.
– IEC 61966-2-1:1999-10, Multimedia systems and equipment – Colour measurement and management –
Part 2-1: Colour management – Default RGB colour space – sRGB.
– IEC 61966-2-1/Amd.1:2003, Multimedia systems and equipment – Colour measurement and
management – Part 2-1: Colour management – Default RGB colour space – sRGB.
– ISO 3166-1:1997, Codes for the representation of names of countries and their subdivisions – Part 1:
Country codes.
– ISO 3166-2:1998, Codes for the representation of names of countries and their subdivisions – Part 2:
Country subdivision code.
– ISO 5807:1985, Information processing – Documentation symbols and conventions for data, program
and system flowcharts, program network charts and system resources charts.
– ISO 8601:2000, Data elements and interchange formats – Information interchange – Representation of
dates and times.
– ISO/IEC 8859-1:1998, Information technology – 8-bit single-byte coded graphic character sets – Part 1:
Latin alphabet No. 1.
– ISO/IEC 11578:1996, Information technology – Open Systems Interconnection – Remote Procedure Call
(RPC).
2.3 Additional references
– IEEE Std. 754-1985, IEEE Standard for Binary Floating-Point Arithmetic.
– IETF RFC 1766 (1995), Tags for the Identification of Languages.
– IETF RFC 1950 (1996), ZLIB Compressed Data Format Specification version 3.3.
– IETF RFC 1951 (1996), DEFLATE Compressed Data Format Specification version 1.3.
– IETF RFC 2045 (1996), Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
Message Bodies.
– IETF RFC 2279 (1998), UTF-8, a transformation format of ISO 10646.
– IETF RFC 2396 (1998), Uniform Resource Identifiers (URI): Generic Syntax.
– W3C (2008), Cascading Style Sheets, level 1 (CSS1) Specification.
2 Rec. ITU-T T.805 (01/2012)
– W3C (2011), Cascading Style Sheets, level 2, revision 1 (CSS2) Specification.

– W3C (2008), Extensible Markup Language (XML) 1.0, Fifth Edition.

– W3C (1999), HTML 4.01 Specification.
– W3C (2002), XHTML™ 1.0 Extensible HyperText Markup Language, Second Edition.

– W3C (2004), XML Schema Part 0: Primer, Second Edition.
– W3C (2004), XML Schema Part 1: Structures, Second Edition.
– W3C (2004), XML Schema Part 2: Datatypes, Second Edition.
– ICC.1:1998-09, International Color Consortium, File Format for Color Profiles.
3 Definitions
For the purposes of this Recommendation | International Standard, the following definitions apply.
3.1 annotation: Particular region of a page in a JPM document that has associated a URL reference, a note or a
highlight.
3.2 base colour: The colour of an object for which no image data is available.
3.3 BasePage: The original state of the page before it is rendered with layout objects.
3.4 box: A portion of the file format defined by a length and a unique box type. Boxes of some types may contain
other boxes.
3.5 component: A two-dimensional array of samples.
3.6 compound image: An image that may contain scanned images, synthetic images or both, and that preferably
requires a mix of continuous tone and bi-level compression methods.
3.7 compressed hidden text XML: Hidden text XML data compressed using the mechanisms defined in
clause F.2.
3.8 file format: A codestream or codestreams and additional support and information not explicitly required for
decoding of the codestream or codestreams. Examples of such support data include text fields providing security and
historical information, data to support the placement of multiple codestreams within a given data file, and data to
support exchange between platforms or conversions to other file formats.
3.9 fragment: A portion of the codestream for an image. Clause 5.2.5 describes fragment usage.
3.10 hidden text: Symbolic representation for the characters and words found in an image.
3.11 hidden text UUID box: UUID box containing compressed hidden text XML.
3.12 hidden text XML: XML data which describe hidden text and annotations for a single page in a JPM file and
which conform to the schema in Annex H.
3.13 hidden text XML schema: XML schema for hidden text XML, as defined in clause H.1.
3.14 JP2 file: The name of a file in the file format described in Rec. ITU-T T.800 | ISO/IEC 15444-1. Structurally,
a JP2 file is a contiguous sequence of boxes.
3.15 JPM file: The name of a file in the file format described in this International Standard. A JPM file can contain
one or more pages, composed from one or more layout objects, each of which is composed from at most two objects.
Structurally, a JPM file is a contiguous sequence of boxes.
3.16 JPX file: The name of a file in the file format described in Rec. ITU-T T.801 | ISO/IEC 15444-2. Structurally,
a JPX file is a contiguous sequence of boxes.
3.17 layout object: An entity that comprises at most two paired objects or MRC layers.
3.18 main page collection: The main page collection contains all pages and page collections in a file.
3.19 mask object: An object that is used to select the samples of a corresponding image object that are to be
imaged on a page.
3.20 metadata: Additional data associated with the image data beyond the image data.
Rec. ITU-T T.805 (01/2012) 3
3.21 MRC: Mixed raster content; a multi-layer imaging model described in Rec. ITU-T T.44 | ISO/IEC 16485.
3.22 object: An image that is part of a layout object; an MRC layer.
3.23 page: The largest collection of layout objects that can be imaged independently of any other layout objects; a
canvas or frame for imaging.
3.24 page collection: A collection of pages logically grouped together in a JPM file. Each page must be contained
in at least one page collection.
3.25 PageImage: The image created by rendering the BasePage with the layout objects. The PageImagek are the
images created by rendering the BasePage with the first k layout objects.
3.26 primary page collection: A page collection which provides back and forward navigation in the main
document associated with a page.
3.27 profile: A subset of all possible field values in a file.
3.28 superbox: A box that itself contains a contiguous sequence of boxes (and only a contiguous sequence of
boxes).
4 Abbreviations
For the purposes of this Recommendation | International Standard, the following abbreviations apply. The abbreviations
defined in Rec. ITU-T T.800 | ISO/IEC 15444-1 clause 4 also apply.
DPI Dots per inch
HTX Hidden Text XML
IPR Intellectual Property Rights
JP2 JPEG 2000 File Format defined in Rec. ITU-T T.800 | ISO/IEC 15444-1
JPX JPEG 2000 File Format defined in Rec. ITU-T T.801 | ISO/IEC 15444-2; JPEG 2000 File Format
Extended
JPM JPEG 2000 File Format defined in this International Standard; JPEG 2000 File Format – Multilayer
MRC Mixed Raster Content
PPCLoc Primary Page Collection Locator
UUID Universal Unique Identifier
5 General arrangement
The purpose of this clause is to give an overview of this International Standard. Terms defined in previous clauses in
this International Standard will also be introduced. (Terms defined in clauses 3 and 4 of Rec. ITU-T T.800 |
ISO/IEC 15444-1 continue to apply in this International Standard.) Throughout this International Standard, text
formatted as a NOTE in the following form is informative only:
NOTE – Informative text appears here.
This International Standard defines a file format for storing compound images using the JPEG 2000 file format family
architecture. A compound image file contains multiple images, both contiguous tone and bi-level, together with
composition models describing how the individual images are combined to generate the compound image. This
International Standard is based on the multi-layer mixed raster content (MRC) imaging model, defined in Rec.
ITU-T T.44 | ISO/IEC 16485.
This International Standard defines a member of the JPEG 2000 file format family that enables the efficient processing,
interchange and archiving of raster-oriented pages containing a mixture of multi-level and bi-level images. This
efficiency is realized by representing the mixed-content image using multiple layers, determined by image type, and
applying image specific encoding, spatial and colour resolution processing. A rasterized page may contain one or more
image types, such as: multi-level continuous-tone or palettized (contone) content usually associated with naturally
occurring images; bi-level detail associated with text and line-art; and multi-level colours associated with the text and
line-art. This International Standard makes provisions for processing, interchange, and archiving of these image types in
multiple layers and defines composition models which regenerate the desired image.
4 Rec. ITU-T T.805 (01/2012)
5.1 Mixed raster content model
A file that conforms with this International Standard contains one or more pages. The PageImage associated with a page
is generated by combining the page's layout objects with the BasePage.
The BasePage is the initial PageImage before any layout objects have been rendered. The BasePage has the same width
and height as the page and is either transparent or filled with a single colour. BasePage is defined in clause 5.2.2.1. The
layout objects are applied sequentially, in an order defined by the layout object identifier field in the layout object
header boxes, to the BasePage to create the final PageImage. The layout object with a layout object identifier value of 0
is the page thumbnail and is not used in creating the PageImage.
Associated with each layout object is a mask M and an image I. The mask M is an opacity image and has only one
component; I can be greyscale or colour, with one or more components. M and I are defined in clause 5.2.3. Both M and
I have the same width and height as the page.
The following equations show the model for combining the BasePage and a sequence of n layout objects with non-zero
layout object identifier values to create the final PageImage. We will use the notation N[c][x,y] to refer to the sample
value at position (x,y) in component c of an image N.
PageImage [c][x, y] = BasePage[c ][x, y]
(1)
s − M [c][x,y]× PageImage [c][x,y]+ M [0][x,y]× I [c][x,y]
m m m-1 m m
(2)
PageImage [c][x,y]= , m =1, ., n
m
S
m
PageImage[ c][x, y] = PageImage [c][x, y] (3)
where M [c][x,y] and I [c][x,y] are the image sample values of component c at position (x,y)
m m
bit depth of Mm
of the mth layout object's mask M and image I respectively, and s = 2 – 1 . M, I and
m
BasePage are defined in clauses 5.2.2.1 and 5.2.3. PageImage[c][x,y] is the final page image,
obtained after combining all n layout objects associated with the page.
NOTE – Figure 1 shows a simple example of a PageImage constructed from a BasePage with a single solid colour and two layout
objects. Note that white in the masks M and M denotes a value of 0.
0 1
NOTE – In a JPM file, the mask and image objects in a layout object typically have different spatial resolutions. Therefore, they
must be scaled to the same resolution and to the page resolution before they are combined to create a page image according to
Equations 1-3. In a JPM file, the size of the mask, image and page are specified in page grid units, but their resolutions may not
be specified. The scaling of the mask and image is specified by a scale factor. The method of scaling is not specified in this
International Standard, although informative guidelines for scaling of the mask and image are provided. The page image would
then be scaled to the resolution of the output device for rendering on a display or printer. As described here, there would be two
separate scaling operations: in the first, the mask and image of successive layout objects are scaled to a common resolution and
combined on the page; in the second, the resulting page image is scaled to the device resolution. In practice, these two scaling
operations are often combined into a single, device-dependent and implementation-specific scaling operation.

Rec. ITU-T T.805 (01/2012) 5
PageImage I M
0 1 1
PageImage I M
1 2 2
Compound Cat
PageImage
Compound Cat
Figure 1 – Example compound document
5.2 File elements and structure
The files that conform to the format defined in this International Standard are called JPM files. At its core, a JPM file is
a sequence of pages, where each page in turn is a sequence of layout objects. A layout object normally consists of a
mask object and an image object. Mask and image objects are composited to build up the final page image according to
Equations 1-3. The key elements or boxes of a JPM file are: page collections, page, layout object, and object. An object
points to its image data directly via a contiguous codestream box or indirectly via a fragment table box. Like all
members of the JPEG 2000 file format family, a JPM file begins with a JPEG 2000 signature box and a file type box. A
compound image header box, containing general information about the file, is then followed by page collection, page,
fragment table, contiguous codestream, media data and general metadata boxes. Refer to Annex B for constraints on the
location of boxes in a JPM file.
This list illustrates the hierarchical relationship between the key elements in a JPM file. A particular order of these
boxes is not implied. Full details of all the boxes may be found in Annex B.
JPEG 2000 signature
File type
Compound image header
Page collection
Page
Layout object
Mask object
Image object
Fragment table
Codestream fragment
Contiguous codestream
6 Rec. ITU-T T.805 (01/2012)
5.2.1 Page collections
A JPM compatible file consists of a sequence of pages, each represented by a page box which occurs at the top level of
the file and each of which can be rendered independently of any other page. Page collections are used to logically group
pages in a JPM file. Page collections can be logically nested, so that a page collection can itself consist of one or more
page collections and/or one or more pages. Page collections referred to from other page collections are called subsidiary
page collections. All pages in a JPM file must be pointed to by at least one page collection.
A page can be said to be contained in a page collection, but this does not mean that the page box is located within the
page collection box. It is not. Page boxes and page collection boxes both occur at the top level of the file and are not
contained within other boxes.
A JPM file contains one page collection known as the main page collection which is used to locate all pages of the file.
Any additional page collections in a JPM file are logically nested within the main page collection (see clause 5.2.1.3). A
page collection box contains an optional label box, optional metadata (XML and/or UUID) boxes, and a page table box
that contains the locations of the pages and page collections belonging to the page collection.
It is recommended that optimized files have the main page collection located near the beginning of the file. While page
boxes and page collection boxes occur at the top level of the file, they may be located in external files. This case may be
viewed as equivalent to being at the top level of the file.
Each page in a JPM file has a primary page collection. The purpose of a primary page collection is to enable navigation
in the primary document to which the page belongs using the sequential order within the primary page collection, thus
providing support for previous page and next page commands.
Every page collection box contains a page table box. The page table box entries point to the locations of the page and
page collection boxes within the page collection. A flag for each entry specifies whether the location is that of a page
box or page collection box, as well as indicating whether the box contains a thumbnail or metadata.
By walking the tree of pages and logically nested page collections in a page's primary page collection, all pages in the
page's primary document can be reached. Every page (with the exception of a self-contained JPM file containing only a
single page) has a primary page collection locator or PPCLoc box. This box points to the primary page collection of the
page and provides an index, PIx, into that page collection's page table where the page is referenced. Then the next page
and previous page can be found by walking one page forward or backward from the current page.
NOTE – Multiple page collections can exist in a JPM file. Some may have functions other than basic navigation. A table of
figures could point to those pages containing figures. A section table or chapter table might point to only the first pages of
sections or chapters. Any page collections of this sort must be auxiliary page collections, since they provide redundant pointers to
pages and page collections and are sparse rather than comprehensive (see clause 5.2.1.3).
NOTE – Figure 2 illustrates a logical grouping of page collections PC and pages P in a JPM file. PCa is the main page collection
and the primary page collection for pages P0, P8 and P9 and page collections PCb, PCc and PCe. In a JPM file, the page table
box of the page collection box for PCa would reference the page boxes for P0, P8 and P9, and the page collection boxes for PCb,
PCc and PCe. The primary page collection locator boxes in these page and page collection boxes would reference the page
collection box for PCa.
PCb is a subsidiary page collection of PCa and the primary page collection for pages P1, P6 and P7 and for page
collection PCd. PCd is the primary page collection for pages P2, P3, P4 and P5. PCc is the primary page collection for
pages P10 and P11.
PCe is an auxiliary page collection, which references page collection PCc and page P5.
PCa
PCe
P0 PCb P8 P9 PCc
P1 PCd P6 P7 P10 P11
P1 P3 P4 P5
Figure 2 – Example of page collections and pages
Rec. ITU-T T.805 (01/2012) 7
5.2.1.1 Main page collection
Each JPM file has one main page collection. The purpose of the file's main page collection is to comprehensively list all
pages (and subsidiary page collections) within a JPM file. This allows random seeking to any of the pages in the file.
The page boxes for these pages occur at the top level of the file format, as do media data boxes containing fragments of
codestreams. Since these media data boxes may be large and since they would likely be interspersed with page boxes,
the page boxes might be widely separated in the file. In a JPM file containing a client copy of several browsed pages of
a server's JPM file, each successively viewed page and some portion of its codestream fragments would be appended in
turn to the bottom of the file. An update to the main page collection allows each of these new pages to be located.
The main page collection comprehensively references all pages and page collections by means of a hierarchical
arrangement. Some pages may be referenced from a page collection beneath the main page collection, but all pages and
page collections are part of the tree structure of the main page collection.
A JPM file optimized for browsing would have the main page collection near the front of the file. On the other hand, a
client copy created during a browsing session would likely have the main page collection appended to the end of the file
each time it is modified. The old main page collection's page collection box could then be left in place but have its box
type changed from "pcol" to "free". A later garbage collection step could delete these free boxes. Because of cases like
this, the file format has a pointer to the main page collection included in the compound image header box near the top of
the file. This makes it easy to locate the main page collection box.
5.2.1.2 Primary page collection
Each page or page collection has a primary page collection. By way of distinction, each JPM file has a main page
collection. A primary page collection is a property of a page or page collection, not a property of a JPM file.
The primary page collection of a page is the page collection where a JPM reading application would find the "next
page" and "previous page" for a current page.
A primary page collection locator or PPCLoc box must appear in all page boxes and all page collection boxes, with the
one exception detailed in the next paragraph. The PPCLoc box provides a pointer to the primary page collection of the
page or page collection. This backward pointer enables a comprehensive tree walk to find all the pages and page
collections in the file.
The PPCLoc box is optional only in the case of a single-page, self-contained JPM file (i.e., one which has no external
references). In this case, it appears that the page has no primary page collection, but in fact the file's main page
collection functions as the page's primary page collection.
The primary page collection of a page or page collection may not be in the local JPM file in which that page box or
page collection box is located. The local file may, for example, have three single pages, each of which has been copied
from one of three different remote files. Keeping the original primary page collection pointers for these pages pointing
to the original remote files allows a user to keep browsing the original source document via next page and previous
page commands.
The main page collection for a file may be a copy of a subsidiary page collection on a remote server, for instance, in
which case it would have the parent page collection on that remote server as its primary page collection. When the main
page collection does not have a primary page collection, then the main page collection box shall not contain a PPCLoc
box.
5.2.1.3 Auxiliary page collection
Auxiliary page collections are page collections which provide redundant pointers to pages already pointed to in the
logical tree structure of the main page collection. Examples of auxiliary page collections could include a list of figures
or a list of tables. Auxiliary page collections still appear in the logical tree structure of the main page collection so that
they can be located, but a flag is used to mark them as auxiliary. This way, a decoding application knows they are not to
be used to perform a comprehensive tree walk through all the pages referenced in the main page collection.
Auxiliary page collections appear in the main page collection to assist an application in locating them within the file,
but they are not part of the logical tree that is walked to comprehensively locate all pages. They instead provide a
redundant means of reaching selected pages and thus should be ignored when trying to determine the natural page order
of the file. Auxiliary page collections can appear down in the hierarchy of the main page collection; they need not occur
at the top level.
Auxiliary page collections should be labelled by means of a label box in order to be useful to a receiving application. If
they are labelled, then a decoding application could present the label to the end user and offer such options as "next
page in List of Figures" and "previous page in List of Figures".
8 Rec. ITU-T T.805 (01/2012)
As an example, if page 17 appears in the "List of Figures" page collection, the decoding application would return to that
page collection to get the next or previous page containing a figure, but would return to the primary page collection for
page 17 (by means of the PPCLoc box in page 17's page box) to find the next page or previous page.
5.2.2 Pages
A page in a JPM file is represented by a page box, a superbox that consists of a page header box, containing general
information about the page, a page collection locator box, containing the location of the page's primary page collection,
an optional base colour box, which describes the base page colour, optional metadata boxes, and layout object boxes,
one for each layout object on the page. Full details of these boxes may be found in clause B.2.
Pages occur at the top level of the file format. This means incremental updates to the file may be accomplished by
simply appending new pages to the end of the file. Page boxes and boxes containing codestreams or portions of
codestreams may be intermixed in the file.
With the exception of document thumbnails, each image in a JPM files is logically associated with at least one page.
5.2.2.1 Base page
The BasePage is the initial PageImage before any layout objects have been rendered. Let page_width and page_height
be the width and height of the page respectively, as signalled in the page header box.
Let spc be the colourspace in which the I images are to be combined to generate a PageImage. BasePage is an image
with dimensions page_width and page_height and colourspace spc.
If the PColour field of the page header box is 0 then the BasePage is transparent and contains the sample values of any
underlying image, converted to the colourspace spc.
If the PColour field of the page header box is 1 then every BasePage sample contains the representation of white in the
colourspace spc.
If the PColour field of the page header box is 2 then every BasePage sample contains the representation of black in the
colourspace spc.
If the PColour field of the page header box is 255 then there is a mandatory base colour box within the page box and
every BasePage sample contains the spc representation of the colour indicated by the base colour box.
5.2.3 Layout objects
Within a page box, there are as many layout object boxes as there are layout objects on the page. A layout object box is
a superbox that consists of a layout object header box, containing general information about the layout object, optional
boxes containing metadata associated with the layout object, and one or two object boxes – either an image object box
and/or mask object box, or a combined image/mask object box.
Each object box contains an object header box identifying whether the object represents an image, a mask or a
combined image/mask, specifying the location of any codestream associated with the object and containing positioning
information for the object.
An image object typically has a codestream associated with it, but may not, in which case the NoCodestream field in the
image object header is set to 1. An image object may also have an associated constant colour or image base colour. If an
image object does not have an associated codestream, then it must have a defined image base colour. A mask object or
image/mask object, if present, must have a codestre
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