ISO 23504-1:2020

INTERNATIONAL ISO
STANDARD 23504-1
First edition
2020-07
Corrected version
2020-09
Document management
applications — Raster image transport
and storage —
Part 1:
Use of ISO 32000 (PDF/R-1)
Applications de gestion de documents — Transport et stockage des
images tramées —
Partie 1: Utilisation de l'ISO 32000 (PDF/R-1)
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Notation . 2
5 Version identification . 2
6 Conformity requirements . 3
6.1 General . 3
6.2 PDF subset . 3
6.2.1 General. 3
6.2.2 Unencrypted PDF/R files . 3
6.2.3 Encrypted PDF/R files. 3
6.2.4 Unencrypted and encrypted PDF/R files . 4
6.3 Catalog dictionary . 4
6.4 Metadata . 4
6.4.1 General. 4
6.4.2 Document level and page level metadata streams . 4
6.4.3 Document information dictionary . 5
6.4.4 XMP Metadata . 5
6.5 Page objects . 5
6.5.1 General. 5
6.5.2 Page tree nodes . 5
6.5.3 Media box . 5
6.5.4 Annots array and digital signatures . 6
6.5.5 Resources dictionary . 6
6.5.6 Rotation . 6
6.5.7 Content stream . 6
6.6 Strips . 7
6.6.1 General. 7
6.6.2 Bitonal images . 7
6.6.3 Grayscale images . . 8
6.6.4 RGB images . 8
6.7 Incremental updates . 9
6.8 Encryption . 9
Annex A (informative) Application notes .10
Bibliography .16
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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 ISO documents 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 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 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.
This document was prepared by Technical Committee ISO/TC 171, Document management applications,
Subcommittee SC 2, Document file formats, EDMS systems and authenticity of information.
This corrected version of ISO 23504-1:2020 incorporates the following corrections:
— Angled brackets inserted around 'total height' in the numerator of the second formula in A.4;
— ']' added to the line before '/Whitepoint' in A.8.
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.
iv © ISO 2020 – All rights reserved

Introduction
This document describes PDF/R (Raster), a strict subset of the PDF file format, for storing, transporting
and exchanging multi-page raster-image documents, especially scanned documents and photographs.
PDF/R provides the portability of PDF while offering the core functionality of TIFF. Bitonal, grayscale
and RGB images are supported. Compression options include JPEG, lossless CCITT Group 4 Fax and
uncompressed.
This document describes the restrictions that differentiate a PDF/R file from a standard PDF file.
Additionally, it specifies (see Clause 5) that a comment is used to identify files claiming to be PDF/R
files. There is no intention herein to claim any intellectual property that is not present in the existing
PDF standard, nor claim any IP that is covered therein.
PDF/R is intended to be a standard format for storing, transporting and exchanging scanned documents.
As a subset of PDF, it takes advantage of the widespread support for viewing, printing and processing
PDF files. As a narrowly restricted subset of PDF, it is much simpler to generate and interpret, allowing
it to replace the TIFF and JPEG file formats for capture and delivery of scanner output.
PDF/R imposes many restrictions on PDF content and layout, for the following benefits:
— files can be read and written without a full PDF parser or generator;
— files can be created efficiently from raster images;
— files can be generated using a fixed-size raster data buffer;
— images can be located and read efficiently with comparatively simple code;
— PDF/R files can be quickly and easily identified as such by software;
— PDF/R supports effective and readily available compression algorithms.
PDF/R has important advantages over the full PDF format for storing scanned documents:
— the raster image data can be recovered;
— a complex rendering engine is not required;
— it provides a precise, well-defined target, simplifying engineering design and testing.
PDF/R retains optional PDF security features useful for protecting content:
— encryption is allowed for implementations that need to protect document content at rest.
PDF/R retains optional PDF digital signature features useful for authenticating content:
— one or more digital signatures may be used for implementations that require verification of the
document origin, authenticity, date or time of creation, and so on.
PDF/R has important advantages over TIFF and JPEG for storing scanned documents:
— compared to TIFF, it has far fewer and simpler variants;
— compared to TIFF, compression is simpler and better standardized and supported;
— compared to TIFF, PDF files can be natively viewed and printed on more platforms;
— unlike JPEG, it is natively multi-page and handles bitonal images.
PDF/R was created by collaboration between the TWAIN Working Group, which originated the PDF/R
concept, and the PDF Association, which provided PDF technology expertise and perspective as well
as means of communicating with the PDF software industry to ensure a diverse range of relevant
viewpoints was represented.
INTERNATIONAL STANDARD ISO 23504-1:2020(E)
Document management applications — Raster image
transport and storage —
Part 1:
Use of ISO 32000 (PDF/R-1)
1 Scope
This document defines a subset of ISO 32000 suitable for storage, transport and exchange of multi-page
raster-image documents, including but not limited to scanned documents. Bitonal, grayscale and RGB
images are supported. Compression options for image data streams include JPEG, CCITT Group 4 Fax
and uncompressed.
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 32000-1:2008, Document management — Portable document format — Part 1: PDF 1.7
1)
ISO 32000-2 :2020, Document management — Portable document format — Part 2: PDF 2.0
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:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
page image
image of one side of a physical page (3.2)
3.2
physical page
physical media object with two sides
3.3
unencrypted PDF/R file
file conforming to this PDF/R specification that does not contain an Encrypt dictionary in the trailer
dictionary
3.4
encrypted PDF/R file
file conforming to this PDF/R specification that does contain an Encrypt dictionary in the trailer
dictionary
1) Under preparation. Stage at the time of publication: ISO DIS 32000-2.
4 Notation
PDF operators, PDF keywords, the names of keys in PDF dictionaries, and other predefined names are
written in bold font; operands of PDF operators or values of dictionary keys are written in italic font.
Some names can also be used as values, depending on the context, and so the styling of the content will
be context-specific.
EXAMPLE 1 The Sig value for the FT key.
Token characters used to delimit objects and describe the structure of PDF files, as defined in
ISO 32000-1:2008, 7.2.1, may be identified by their ISO/IEC 646-character name written in uppercase in
bold font followed by a parenthetic two-digit hexadecimal character value with the suffix “h”.
EXAMPLE 2 CARRIAGE RETURN (0Dh).
2)
Text string characters, as defined in ISO 32000-1:2008, 7.9.2, may be identified by their ISO/IEC 10646
character name written in uppercase in bold font followed by a parenthetic four-digit hexadecimal
character code value with the prefix “U+”.
EXAMPLE 3 EN SPACE (U+2002).
5 Version identification
A PDF file conforming to the PDF/R specification is identified by one comment line near the end of the
file, immediately before the last occurrence of the line in the file containing the startxref key. The
comment shall be:
%PDF-raster-x.y
where
“x” (the digit before the decimal point) is the major version number
“y” (the digit after the decimal point) is the minor version number
The PDF/R version number for PDF files conforming to this document shall be 1.0. New major versions
may be incompatible with previous versions; new minor versions are expected to not break existing
readers.
This comment line marks the file as intended to conform to this specification.
EXAMPLE
trailer
<<
/Info 58 0 R
/Size 59
/Root 1 0 R
/ID
[ 

]
>>
%PDF-raster-1.0
startxref
%%EOF
2) Under preparation. Stage at the time of publication: ISO/IEC DIS 10646.
2 © ISO 2020 – All rights reserved

6 Conformity requirements
6.1 General
A conforming PDF/R file shall conform to all requirements listed in 6.2, “PDF subset” to 6.8, “Encryption”.
6.2 PDF subset
6.2.1 General
Conformity of unencrypted and encrypted PDF/R files only differs regarding the use of encryption.
Encrypted PDF/R files make use of encryption features introduced in ISO 32000-2, and not available
in ISO 32000-1. The definition of, and the requirements for, any other feature allowed in a PDF/R file
do not differ between ISO 32000-1 and ISO 32000-2. For the sake of simplicity, all requirements for
PDF/R files, with the exception of those for the use of encryption, are specified on the background of
ISO 32000-1.
6.2.2 Unencrypted PDF/R files
A PDF/R-conforming file that is not encrypted shall adhere to all the requirements of ISO 32000-1 as
modified by this document.
The header shall be one of the following:
— “%PDF-1.4”;
— “%PDF-1.5”;
— “%PDF-1.6”;
— “%PDF-1.7”.
NOTE If the contents of the file are inconsistent with the version number in the header processing results
will be implementation dependent.
No filters other than the following shall be used in an unencrypted PDF/R file:
— FlateDecode;
— CCITTFaxDecode (only for bitonal images);
— DCTDecode (only for 8-bit grayscale or RGB images).
6.2.3 Encrypted PDF/R files
A PDF/R-conforming file that is encrypted shall adhere to all requirements of ISO 32000-1, as modified
by this document, with the following exceptions:
— the header shall be “%PDF-2.0”;
— the file shall adhere to all requirements of ISO 32000-2:2020, 7.6, “Encryption”, as modified by 6.8,
“Encryption”, in this document.
Only the following filters shall be allowed in an encrypted PDF/R file:
— FlateDecode;
— CCITTFaxDecode (only for bitonal images);
— DCTDecode (only for 8 bit grayscale or RGB images);
— Crypt.
6.2.4 Unencrypted and encrypted PDF/R files
All indirect references shall have a generation number equal to zero.
All objects referred to be indirect references shall be listed.
NOTE 1 This precludes indirect object references to a non-existent object as described in ISO 32000-1:2008,
7.3.9, “Null Object”.
Stream dictionaries shall not contain a Type key with a value of ObjStm.
NOTE 2 This precludes the use of object streams described in ISO 32000-1:2008, 7.5.7, “Object streams”.
6.3 Catalog dictionary
The Catalog dictionary shall contain the entries required by ISO 32000-1:2008, Table 28. It
shall not contain any optional entries except zero, one or more of the following entries: Version,
ViewerPreferences, PageLayout, PageMode, AcroForm, and Metadata.
6.4 Metadata
6.4.1 General
The Catalog dictionary of a conforming file may contain the Metadata key for which the value is a
metadata stream as defined in ISO 32000-1:2008, 14.3.2.
Page dictionaries may contain the Metadata key for which the value is a metadata stream as defined in
ISO 32000-1:2008, 14.3.2. This metadata stream, if present, shall contain entries with metadata specific
to the page object.
6.4.2 Document level and page level metadata streams
The document level metadata stream and page level metadata streams may use properties defined
[5]
in ISO 16684-1:2019 (XMP) or custom properties. Where custom properties are used, namespaces
shall be used in such a fashion that conflicts are avoided with other entries using the same property
name. Each organization wishing to define and use its own custom properties shall define a suitable
namespace based on a URL that is under the organization’s control.
EXAMPLE 1 Examples for namespaces based on which custom properties can be defined:
— http:// ns .twain .org/ ns/ pdfraster/ v1/ extra _metadata
— http:// ns .twain .org/ ns/ pdfraster/ v1/ some _other _fields
— http:// ns .some _company .com/ ns/ pdf _raster/ version _1/ company _specific _fields
EXAMPLE 2 Properties using the same name that are based on different namespaces:
rdf:about=""
xmlns:org_a="http://ns.org_a.com/pdfraster/1.0/"
xmlns:org_b="http://ns.org_b.com/pdfraster/1.0/"
ABC-123
987-654-321:tre-hgf-bvc

[1]
The TWAIN Working Group provides guidanc
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