ISO/IEC 19794-6:2011

Information technology — Biometric data interchange formats — Part 6: Iris image data

ISO/IEC 19794-6:2011 specifies iris image interchange formats for biometric enrolment, verification and identification systems. The image information might be stored as an array of intensity values optionally compressed with ISO/IEC 15948 or ISO/IEC 15444, or an array of intensity values optionally compressed with ISO/IEC 15948 or ISO/IEC 15444 that might be cropped around the iris, with the iris at the centre, and which might incorporate region-of-interest masking of non-iris regions. ISO/IEC 19794-6:2011 does not establish requirements on the optical specifications of cameras, requirements on photometric properties of iris images, or requirements on enrolment processes, workflow and use of iris equipment.

Technologies de l'information — Formats d'échange de données biométriques — Partie 6: Données d'image de l'iris

General Information

• Status: Published
• Publication Date: 28-Sep-2011
• ICS: 35.040 - Information coding
• 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 - Biometrics
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 06-Sep-2024

Relations

• Amended By: ISO/IEC 19794-6:2011/Amd 1:2015 - Information technology — Biometric data interchange formats — Part 6: Iris image data — Amendment 1: Conformance testing methodology and clarification of defects
• Effective Date: 28-Aug-2021
• Amended By: ISO/IEC 19794-6:2011/Amd 2:2016 - Information technology — Biometric data interchange formats — Part 6: Iris image data — Amendment 2: XML encoding and clarification of defects
• Effective Date: 09-May-2020
• Corrected By: ISO/IEC 19794-6:2011/Cor 1:2012 - Information technology — Biometric data interchange formats — Part 6: Iris image data — Technical Corrigendum 1
• Effective Date: 18-Dec-2021
• Revises: ISO/IEC 19794-6:2005 - Information technology — Biometric data interchange formats — Part 6: Iris image data
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 19794-6
Second edition
2011-10-01
Information technology — Biometric data
interchange formats —
Part 6:
Iris image data
Technologies de l'information — Formats d'échange de données
biométriques —
Partie 6: Données d'image de l'iris

Reference number
©
ISO/IEC 2011
©  ISO/IEC 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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ii © ISO/IEC 2011 – All rights reserved

Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Conformance . 1
3  Normative references . 2
4  Terms and definitions . 2
5  Symbols and abbreviated terms . 3
6  Iris image content specification . 3
6.1  General . 3
6.2  Uncropped Iris Image . 4
6.3  VGA Iris Image . 4
6.4  Cropped Iris Image . 5
6.5  Cropped and Masked Iris Image . 6
7  Iris image format specification . 7
7.1  General . 7
7.2  Iris image biometric data record . 7
7.3  Iris general header structure . 8
7.4  Iris representation header structure . 8
7.5  Representation body . 12
8  Registered Format Type Identifier . 12
Annex A (normative) Conformance testing methodology . 14
Annex B (informative) Iris image capture . 15
Bibliography . 19

© ISO/IEC 2011 – 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.
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 19794-6 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 37, Biometrics.
This second edition cancels and replaces the first edition (ISO/IEC 19794-6:2005), which has been technically
revised.
ISO/IEC 19794 consists of the following parts, under the general title Information technology — Biometric data
interchange formats:
 Part 1: Framework
 Part 2: Finger minutiae data
 Part 3: Finger pattern spectral data
 Part 4: Finger image data
 Part 5: Face image data
 Part 6: Iris image data
 Part 7: Signature/sign time series data
 Part 8: Finger pattern skeletal data
 Part 9: Vascular image data
 Part 10: Hand geometry silhouette data
 Part 11: Signature/sign processed dynamic data
 Part 13: Voice data
 Part 14: DNA data
iv © ISO/IEC 2011 – All rights reserved

Introduction
The purpose of this part of ISO/IEC 19794 is to define a standard for exchange of iris image information. This
part of ISO/IEC 19794 contains a specific definition of attributes, a data record format for storing and
transmitting the iris image and certain attributes, and conformance criteria.
Currently, exchange of iris information between equipment from different vendors can be done using images
of the eye. While some applications can successfully operate with full size uncompressed rectilinear images,
there are others for which this is expensive with respect to storage and bandwidth. To provide interoperability
among vendors, this part of ISO/IEC 19794 also defines compact representations of the human iris.
This part of ISO/IEC 19794 revises ISO/IEC 19794-6:2005 for interoperable iris data formats. The revision has
focused mainly on three sets of issues: (1) compact image data formats; (2) acceptable compression targets
and algorithms; and (3) specification of data to be included in records and record headers in coordination with
harmonization efforts across all the parts of ISO/IEC 19794, replacing the former header structures.
Before this revision, the standard iris image format was a 307 kB image array (640 x 480), with optional JPEG
compression (ISO/IEC 10918), but the recommended maximum compression factor was set arbitrarily at 6:1
(ISO/IEC 19794-6:2005, A.1.6). Meanwhile, academic papers appeared [5] showing that the 307 kB image
size could be reduced by about a factor of 150:1, to around 2 kB, with minimal impairment, provided that
JPEG2000 (ISO/IEC 15444) was the compression algorithm used, not JPEG (ISO/IEC 10918), and also that
cropping and region-of-interest masking was used. Small payload storage devices (e.g. ISO/IEC 7816
smartcard), and limited bandwidth transmission protocols, mandated that iris images be reduced to a few kB.
ISO/IEC 19794-6:2005 had attempted to provide for this by polar sampling of iris pixels, but vulnerabilities and
defects in polar methods were pointed out and so in January 2008, WG3 voted to remove the old polar
formats. NIST offered to undertake an extensive, independent, empirical investigation of various proposals
and compressibility claims, producing in late 2009 the Interoperable Iris Exchange (“IREX-1”) Report [8]. The
new image data formats in this part of ISO/IEC 19794 are based empirically on the IREX-1 conclusions. In
addition to the two new compact formats, iris images are also amenable to lossless compression. The lossless
PNG standard, ISO/IEC 15948, may be applied to preserve completely the iris texture while affording iris
image sizes in the range of 20 kB to 70 kB, well below those achievable for uncompressed images.
In addition, Annex A, when published as Amendment 1 of this part of ISO/IEC 19794, will include normative
assertions for testing conformance of iris image records. Annex B of this part of ISO/IEC 19794 gives
recommendations on iris image capture.
While the data structure advanced here is syntactically incompatible with the previous version, software
implementations can differentiate the records by inspecting the version number in the second four bytes of the
record.
© ISO/IEC 2011 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 19794-6:2011(E)

Information technology — Biometric data interchange
formats —
Part 6:
Iris image data
1 Scope
This part of ISO/IEC 19794 specifies iris image interchange formats for biometric enrolment, verification and
identification systems. The image information might be stored as
 an array of intensity values optionally compressed with ISO/IEC 15948 or ISO/IEC 15444, or
 an array of intensity values optionally compressed with ISO/IEC 15948 or ISO/IEC 15444 that might
be cropped around the iris, with the iris at the centre, and which might incorporate region-of-interest
masking of non-iris regions.
This part of ISO/IEC 19794 does not establish
 requirements on the optical specifications of cameras, or
 requirements on photometric properties of iris images, or
 requirements on enrolment processes, workflow and use of iris equipment.
2 Conformance
A biometric data record conforms to this part of ISO/IEC 19794 if it satisfies all of the normative requirements
related to
 its data structure, data values and the relationships between its data elements, as specified
throughout Clause 7 of this part of ISO/IEC 19794, and
 the relationship between its data values and the input biometric data from which the biometric data
record was generated, as specified throughout Clause 6 of this part of ISO/IEC 19794.
A system that produces biometric data records is conformant to this part of ISO/IEC 19794 if all biometric data
records that it outputs conform to this part of ISO/IEC 19794 (as defined above) as claimed in the
Implementation Conformance Statement (ICS) associated with that system. A system does not need to be
capable of producing biometric data records that cover all possible aspects of this part of ISO/IEC 19794, but
only those that are claimed to be supported by the system in the ICS. The test for output record conformance
shall be conducted in accordance with the normative content of Annex A.
A system that uses biometric data records is conformant to this part of ISO/IEC 19794 if it can read, and use
for the purpose intended by that system, all biometric data records that conform to this part of ISO/IEC 19794
(as defined above) as claimed in the ICS associated with that system. A system does not need to be capable
of using biometric data records that cover all possible aspects of this part of ISO/IEC 19794, but only those
that are claimed to be supported by the system in an ICS.
© ISO/IEC 2011 – All rights reserved 1

3 Normative references
The following referenced documents are indispensable for the application 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 15444-1, Information technology — JPEG 2000 image coding system: Core coding system
ISO/IEC 15948:2004, Information technology — Computer graphics and image processing — Portable
Network Graphics (PNG): Functional specification
ISO/IEC 19794-1, Information technology — Biometric data interchange formats — Part 1: Framework
4 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19794-1 and the following apply.
4.1
grey scale
continuous-tone image that has one component, which is luminance
4.2
iris
coloured annular structure in the front portion of the eye comprised of muscular and connective tissue and
pigmented layers, that defines the pupil and controls its size
4.3
iris centre
centre of a circle modelling the boundary between iris and sclera
4.4
iris radius
radius of a circle modelling the boundary between iris and sclera
4.5
limbus
outer boundary of the iris where it is joined to the sclera
4.6
margin
distance in an image from the iris-sclera border, when modelled as a circle, to the closest image border,
expressed in pixels
NOTE Throughout this part of ISO/IEC 19794, margins are defined in terms of the iris radius R. When written as an
ordered pair, the order is (horizontal, vertical).
EXAMPLE (0,6R, 0,2R) indicates that for an iris radius of R, there shall be margins of image data 0,6·R to the right
and left of the iris and 0,2·R above and below the iris.
4.7
Modulation Transfer Function
ratio of the image modulation to the object modulation as a function of spatial frequency
4.8
pupil
optical opening in the centre of the eye that serves as a variable ligh
...