ISO/IEC 39794-2

Information technology — Extensible biometric data interchange formats — Part 2: Finger minutiae data

Technologies de l'information — Formats extensibles d'échange de données biométriques — Partie 2: Titre manque

General Information

• Status: Not Published
• ICS: 35.240.15 - Identification cards. Chip cards. Biometrics
• Technical Committee: ISO/IEC JTC 1/SC 37 - Biometrics
• Drafting Committee: ISO/IEC JTC 1/SC 37/WG 3 - Biometric data interchange formats
• Current Stage: 6000 - International Standard under publication
• Completion Date: 22-Jun-2023

Standards Content (Sample)

DRAFT INTERNATIONAL STANDARD
ISO/IEC DIS 39794-2
ISO/IEC JTC 1/SC 37 Secretariat: ANSI
Voting begins on: Voting terminates on:
2022-05-24 2022-08-16
Information technology — Extensible biometric data
interchange formats —
Part 2:
Finger minutiae data
ICS: 35.240.15
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
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NOT BE REFERRED TO AS AN INTERNATIONAL
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ISO/IEC DIS 39794-2:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
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NOTIFICATION OF ANY RELEVANT PATENT
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PROVIDE SUPPORTING DOCUMENTATION. © ISO/IEC 2022

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ISO/IEC39794-2:2022
ISO/IECJTC1/SC37/WG3
ISO/IEC DIS 39794-2:2022(E)
Date: 2022-02-19
Information technology —Extensible biometricdatainterchange
formats—Part2:Fingerminutiae data
DISstage
Warning forWDsand CDs
This documentis notan ISOInternationalStandard.Itis distributedfor reviewandcomment.Itis subjectto
changewithout noticeandmaynot bereferredtoasanInternationalStandard.
Recipients ofthis draftare invited to submit,with theircomments,notification ofany relevantpatentrightsof
whichthey are aware andtoprovide supporting documentation.
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2022
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/IEC 2022 – All rights reserved

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ISO/IEC DIS 39794-2:2022(E)
Contents
Foreword . vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.1 capture device spatial sampling rate . 2
3.2 image spatial sampling rate . 2
3.3 palm . 2
3.4 fingerprint image . 2
3.5 friction ridge . 2
3.6 minutia . 2
3.7 typeline . 3
3.8 delta . 3
3.9 core . 3
3.10 4-neighbour of a pixel p . 3
3.11 4-path from pixel p0 to pixel pn . 3
3.12 4-connected set of pixels . 3
3.13 8-neighbour of a pixel p . 4
3.14 8-path from pixel p0 to pixel pn . 4
3.15 8-connected set of pixels . 4
3.16 border ¶S of a set of pixels S . 4
3.17 loop . 4
3.18 whorl . 4
4 Symbols and abbreviated terms . 5
5 Conformance . 5
6 Modality Specific Information . 5
6.1 Purpose . 5
6.2 Minutia description . 6
6.3 Minutia kind . 6
6.3.1 General . 6
6.3.2 Unique minutia . 6
6.3.3 Encoding trifurcations . 7
6.4 Minutia location . 7
6.4.1 General . 7
6.4.2 Coordinate system . 7
6.4.3 Minutia placement on a ridge ending (encoded as valley skeleton bifurcation point) 8
6.4.4 Minutia placement on a ridge bifurcation (encoded as a ridge skeleton bifurcation
point) . 8
6.4.5 Minutia placement on a ridge skeleton endpoint . 9
6.4.6 Usage of the minutia placement by the record and on-card biometric comparison
formats . 10
6.5 Minutiae direction . 10
6.5.1 Angle conventions . 10
6.5.2 Minutia direction of a ridge ending (encoded as valley skeleton bifurcation point) . 11
6.5.3 Minutia direction of a ridge bifurcation (encoded as ridge skeleton bifurcation
point) . 11
6.5.4 Minutia direction of a ridge skeleton end point . 11
6.6 Core and delta placement . 11
© ISO/IEC 2022 – All rights reserved
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ISO/IEC DIS 39794-2:2022(E)
6.7 Encoding of multibyte quantities . 12
7 Abstract data elements . 12
7.1 Purpose . 12
7.2 Finger minutiae data . 13
7.3 Version . 14
7.4 Representation block . 14
7.5 Position . 14
7.6 Impression . 14
7.7 Minutiae data . 15
7.8 Spatial sampling rate . 16
7.9 Ridge end encoding . 16
7.10 Capture date and time . 16
7.11 Capture device . 16
7.11.1 Capture device model identifier . 16
7.11.2 Certification identifier blocks . 16
7.11.3 Certification schemes for finger images . 16
7.11.4 Capture device technology identifier . 17
7.12 Biometric sample quality blocks . 18
7.13 Generic ridge counts . 18
7.14 Four neighbour ridge counts . 19
7.15 Eight neighbour ridge counts . 19
7.16 Core data . 20
7.17 Delta data . 20
7.18 Zonal quality . 21
7.19 PAD data block . 21
7.20 Vendor specific data . 21
7.21 Position computed by capture system . 21
8 Encoding . 22
8.1 Tagged binary encoding . 22
8.2 XML encoding . 22
8.3 On-card biometric comparison format . 22
8.3.1 Overview . 22
8.3.2 Minutia placement . 23
8.3.3 Encoding . 24
8.3.4 Minutia position . 24
8.3.5 Minutia type . 24
8.3.6 Minutia angle . 24
8.3.7 Number of minutiae and truncation . 24
8.3.8 Usage of extended data for the on-card comparison format . 26
8.3.9 Biometric comparison parameters . 34
9 Registered format type identifiers . 38
Annex A (normative) Formal specifications . 39
A.1 ASN.1 module for tagged binary encoding . 39
A.2 XML schema definition for XML encoding . 44
Annex B (normative) Conformance test methodology . 53
B.1 Overview . 53
B.2 Conformance Test Assertions . 57
Annex C (informative) Encoding Examples . 58
C.1 Sample ASN.1 Encoding for Finger Minutia Data . 58
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ISO/IEC DIS 39794-2:2022(E)
C.2 Sample XML Encoding for Finger Minutia Data . 58
Annex D (informative) . 61
D.1 General . 61
D.2 Minutiae detection strategy . 61
D.2.1 Overview "Liberal-conservative" spectrum . 61
D.2.2 Fingerprint boundary . 64
D.2.3 Sweat pore . 64
D.2.4 Touching ridges . 64
D.2.5 Incipient ridge . 64
D.2.6 Crease . 64
D.2.7 Core . 65
D.2.8 Delta . 65
D.3 Minutia characteristics . 65
D.3.1 Rationale . 65
D.3.2 Minutia type . 65
D.3.3 Minutia location tools . 66
D.3.3.1 Consideration of the spatial sampling rate of the underlying finger image . 66
D.3.3.2 Image binarisation . 66
D.3.3.3 Image skeletonization . 66
D.3.3.4 Ridge flow direction . 67
D.3.3.5 Ridge gradient method . 69
D.3.3.6 Minutia location at a ridge skeleton endpoint . 69
D.3.3.7 Minutia location at a ridge skeleton bifurcation point . 70
D.3.3.8 Minutia location at a valley skeleton bifurcation point . 71
D.3.3.9 Minutia direction at a ridge skeleton endpoint . 72
D.3.3.10 Minutia direction at a ridge skeleton bifurcation point . 72
D.3.3.11 Minutia direction at a valley skeleton bifurcation point . 72
D.3.4 Valley skeletal bifurcation method . 73
D.3.4.1 Minutia location at a valley skeleton bifurcation . 74
D.3.4.2 Minutia location at a ridge skeleton bifurcation . 74
D.3.4.3 Angle of a ridge ending . 74
D.3.4.4 Angle of a ridge bifurcation . 78
D.3.5 Minutia quality . 83
D.4 Sample image . 83
© ISO/IEC 2022 – All rights reserved
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ISO/IEC DIS 39794-2:2022(E)
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
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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
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/IEC JTC 1, Information Technology,
Subcommittee SC 37, Biometrics.
A list of all parts in the ISO/IEC 39794 series can be found on the ISO website.
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.
The purchase of this ISO/IEC document carries a copyright licence for the purchaser to use ISO/IEC
copyright in the schemas in the annexes to this document for the purpose of developing, implementing,
installing and using software based on those schemas, subject to ISO/IEC licensing conditions set out in
the schemas.
© ISO/IEC 2022 – All rights reserved
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ISO/IEC DIS 39794-2:2022(E)
Introduction
Biometric data interchange formats enable the interoperability of different biometric systems. The first
generation of biometric data interchange formats has been published between 2005 and 2007 in the first
edition of the multi-part standard ISO/IEC 19794. From 2011 onwards, the second generation of
biometric data interchange formats has been published in the second edition of the established parts and
the first edition of some new parts of ISO/IEC 19794. In the second generation of biometric data
interchange formats, new useful data elements such as data elements related to biometric sample quality
have been added, the header data structures have been harmonized across all parts of ISO/IEC 19794,
and an XML encoding has been added in addition to the binary encoding.
In anticipation of the future need for additional data elements and to avoid future compatibility issues,
ISO/IEC JTC 1/SC 37 has developed ISO/IEC 39794 as third generation of biometric data interchange
formats, defining extensible biometric data interchange formats capable of including future extensions in
a defined way. Extensible specifications in ASN.1 (Abstract Syntax Notation One) and the Distinguished
Encoding Rules of ASN.1 form the basis for encoding biometric data in binary tag-length-value formats.
XML Schema Definitions form the basis for encoding biometric data in XML (Extensible Markup
Language).
This third generation of finger minutia data interchange formats complements the standard ISO/IEC
19794-2:2005 and ISO/IEC 19794-2:2011. The first generation of biometric data interchange formats,
which has been adopted in mass deployments, will be retained in the standards catalogue as long as
required.
This part of ISO/IEC 39794 is intended for those applications requiring the exchange of fingerprint
minutiae data. It will provide implementers with the flexibility to accommodate minutiae captured from
dissimilar devices, varying image sizes, spatial sampling rates, and different grey-scale depths. Use of the
finger minutiae will allow each vendor to implement their own algorithms to determine whether two
fingerprint records are from the same finger.
This part of ISO/IEC 39794 supports both binary and XML encoding, to support a spectrum of user
requirements. With XML, this part meets the requirements of modern IT architectures. With binary
encoding this part is also able to be used in bandwidth or storage constrained environments.
For use on integrated circuit cards and other tokens (see ISO/IEC ISO/IEC 7816-11 and ISO/IEC 24787),
this document also specifies an on-card biometric comparison format and on-card comparison
parameters based on extensible TLV encoding. ISO/IEC 24787 specifies the encapsulation of biometric
data in on-card biometric comparison format into TLV-structured verification data for on-card biometric
comparison.
This part of ISO/IEC 39794 defines specifics of the extraction of key points (called minutiae) from
fingerprint ridge patterns. These specifics include a description of the types of minutiae identified, the
method used for the placement of minutiae on an image, a definition of the coordinate system used, and
the methods used to calculate the angle associated with each minutia.
© ISO/IEC 2022 – All rights reserved
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ISO/IEC DIS 39794-2:2022(E)
Information technology — Extensible biometric data interchange
formats — Part 2: Finger minutiae data
1 Scope
This part of ISO/IEC 39794 specifies
¾ generic extensible data interchange formats for the representation of finger minutia data:
o a tagged binary data format based on an extensible specification in ASN.1
o a textual data format based on an XML schema definition that is capable of holding the same
information as the tagged binary format, and
o an on-card biometric comparison format based on extensible TLV encoding
¾ on-card biometric comparison parameters based on extensible TLV encoding for constructing valid probe data
in the on-card biometric comparison format
¾ examples of data record contents,
¾ application specific requirements, recommendations, and best practices in data determining minutiae location,
direction, and type, and
¾ conformance test assertions and conformance test procedures applicable to this part of ISO/IEC 39794.
NOTE Although ISO/IEC 39794-4 covers finger, palm, toe as well as foot image data, this part of ISO/IEC 39794 only covers finger
minutiae and is neither applicable to palms, toes or feet.
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 docume
...