ISO/IEC 19794-5:2005

INTERNATIONAL ISO/IEC
STANDARD 19794-5
First edition
2005-06-15


Information technology — Biometric data
interchange formats —
Part 5:
Face image data
Technologies de l'information — Formats d'échange de données
biométriques —
Partie 5: Données d'image de la face




Reference number
ISO/IEC 19794-5:2005(E)
©
ISO/IEC 2005

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ISO/IEC 19794-5:2005(E)
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ii © ISO/IEC 2005 – All rights reserved

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ISO/IEC 19794-5:2005(E)


Contents     Page

Foreword .vi
Introduction .vii
1 Scope.1
2 Compliance.3
3 Normative references .3
4 Terms and definitions.3
5 The face record format .5
5.1 Overview.5
5.2 Data Conventions.7
5.2.1 Byte ordering.7
5.2.2 Numeric values.7
5.2.3 Conversion to integer.7
5.2.4 Unspecified field value .7
5.2.5 Unknown field value .7
5.3 The CBEFF Header.7
5.4 The Facial Record Header .8
5.4.1 Format Identifier.8
5.4.2 Version Number .8
5.4.3 Length of Record .8
5.4.4 Number of Facial Images.8
5.5 The Facial Information block.8
5.5.1 Facial Record Data Length .9
5.5.2 Number of Feature Points .9
5.5.3 Gender .9
5.5.4 Eye Colour.10
5.5.5 Hair Colour .10
5.5.6 Property Mask .12
5.5.7 Expression.13
5.5.8 Pose Angle .13
5.5.9 Pose Angle Uncertainty.15
5.6 The Feature Point Block .15
5.6.1 Feature Point Type.15
5.6.2 Feature Point Code .15
5.6.3 MPEG4 Feature Points.17
5.6.4 Eye and nostril centre Feature Points .18
5.7 The Image Information Block .19
5.7.1 Face Image Type .19
5.7.2 Image Data Type.20
5.7.3 Width.20
5.7.4 Height.20
5.7.5 Image Colour Space.20
5.7.6 Source Type .21
5.7.7 Device Type.21
5.7.8 Quality.22
5.8 The Image Data Block.22
5.8.1 Data structure.22
6 The Basic Face Image Type .22
6.1 Inheritance requirements for the Basic Face Image Type .22
6.2 Image data encoding requirements for the Basic Face Image Type.22
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ISO/IEC 19794-5:2005(E)
6.3 Image data compression requirements for the Basic Face Image Type.22


6.4 Format requirements for the Basic Face Image Type .22
6.4.1 Facial Header.22
6.4.2 Facial Information .22
6.4.3 Image Information.23
7 The Frontal Face Image Type.23
7.1 Inheritance requirements for the Frontal Face Image Type.23
7.2 Scene requirements for the Frontal Image Type .23
7.2.1 Purpose.23
7.2.2 Pose .23
7.2.3 Expression.23
7.2.4 Assistance in positioning the face .24
7.2.5 Shoulders .24
7.2.6 Backgrounds.24
7.2.7 Subject and scene lighting.24
7.2.8 Shadows over the face .24
7.2.9 Shadows in eye-sockets.24
7.2.10 Hot spots .24
7.2.11 Eye glasses .24
7.2.12 Eye patches.25
7.3 Photographic Requirements for the Frontal Image Type.25
7.3.1 Purpose.25
7.3.2 No over or under exposure .25
7.3.3 Focus and depth of field.25
7.3.4 Unnatural colour .25
7.3.5 Colour or greyscale enhancement.25
7.3.6 Radial distortion of the camera lens.25
7.4 Digital requirements for the Frontal Image Type.25
7.4.1 Geometry .26
7.4.2 Colour profile .26
7.4.3 Video interlacing .26
7.5 Format requirements for the Frontal Image Type.27
7.5.1 Inheritance requirements .27
7.5.2 Image Information.27
8 The Full Frontal Image Type.27
8.1 Inheritance requirements for the Full Frontal Face Image Type .27
8.2 Scene requirements for the Full Frontal Face Image Type.27
8.3 Photographic requirements for the Full Frontal Face Image Type.27
8.3.1 Introduction.27
8.3.2 Horizontally centred face.28
8.3.3 Vertical position of the face .28
8.3.4 Width of head .28
8.3.5 Length of head .29
8.3.6 Summary of photographic requirements .29
8.4 Digital requirements for the Full Frontal Face Image Type.29
8.4.1 Resolution .29
8.5 Format requirements for the Full Frontal Image Type .29
8.5.1 Inheritance requirements .29
8.5.2 Image Information.29
9 The Token Face Image Type .29
9.1 Inheritance requirements for Token Face Image Type.29
9.2 Digital requirements for the Token Face Image Type .30
9.2.1 Introduction.30
9.2.2 Eye positions.30
9.2.3 Token image geometric format .30
9.2.4 Minimum width Token image .31
9.2.5 Padding.31
9.3 Format requirements for the Token Face Image Type .31
9.3.1 Inheritance requirements .31
9.3.2 Image Information.31
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ISO/IEC 19794-5:2005(E)
Annex A (informative) Best practices for Face Images .32

A.1 Basic Face Images.32
A.1.1 Purpose.32
A.1.2 Feature Point determination.32
A.2 Frontal Images.32
A.2.1 Purpose.32
A.2.2 Expression.32
A.2.3 Assistance in positioning the face .33
A.2.4 Backgrounds.33
A.2.5 Focus and depth of field.33
A.2.6 No unnatural colour .34
A.2.7 Colour calibration .34
A.2.8 Radial distortion of the camera lens.34
A.3 Full Frontal Images. .34
A.3.1 Digital attributes of Full Frontal Images.34
A.3.2 Best practices for use of Full Frontal Images on travel documents .34
A.3.3 Full Frontal Image Compression.39
A.3.4 Full Frontal Image compression using region of interest.41
A.4 Token Images .42
A.4.1 Token image sizes .42
A.4.2 Creation of a Token Image .43
A.4.3 Best practices for digital attributes of Token Images .43
A.4.4 Token Image compression.43
A.4.5 Token Image compression using region of interest.45
A.4.6 Inner and outer regions for the Token Image for the purpose of compression .45
Bibliography.47
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ISO/IEC 19794-5:2005(E)
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 19794-5 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 37, Biometrics.
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
The following parts are under preparation:
 Part 7: Signature/sign behavioral data
 Part 8: Finger pattern skeletal data
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ISO/IEC 19794-5:2005(E)
Introduction

Face images, also commonly referred to as displayed portraits, have been used for many decades to verify

identity of persons. In recent years, digital face images are used in many applications including human
examination as well as computer automated face recognition. Although photographic formats have been
standardized in some cases such as passport and driver license, it is also demanded to define a standard
data format of digital face images to allow interoperability among vendors.
This part of ISO/IEC 19794 is intended to provide a Face Image Format for face recognition applications
requiring exchange of face image data. The typical applications are:
1) human examination of facial images with sufficient resolution to allow a human examiner to ascertain
small features such as moles and scars that might be used to verify identity;
2) human verification of identify by comparison of persons against facial images;
3) computer automated face identification (one-to-many searching);
4) computer automated face verification (one-to-one matching).
To enable many applications on variety of devices, including devices that have the limited resources required
for data storage, and to improve face recognition accuracy, this part of ISO/IEC 19794 specifies not only a
data format, but also scene constraints (lighting, pose, expression etc), photographic properties (positioning,
camera focus etc), digital image attributes (image resolution, image size etc).
Several image types are introduced to define categories that satisfy requirements of some applications. Each
requirement is specified for each image type.
The record format specified in this part of ISO/IEC 19794 is designed to be embedded in a CBEFF-compliant
structure specified in ISO/IEC 19785. The embedment in the CBEFF structure is described in ISO/IEC 19794-1.
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INTERNATIONAL STANDARD ISO/IEC 19794-5:2005(E)

Information technology — Biometric data interchange
formats —
Part 5:
Face image data
1 Scope
This part of ISO/IEC 19794
 specifies a record format for storing, recording, and transmitting the information from one or more facial
images within a CBEFF data structure,

 specifies scene constraints of the facial images,
 specifies photographic properties of the facial images,
 specifies digital image attributes of the facial images.
Each requirement is specified for the following Face Image Types, respectively.
 Basic: This is the fundamental Face Image Type that specifies a record format including header and
image data. All Face Image Types adhere to the properties of this type. No mandatory scene,
photographic and digital requirements are specified for this image type.
 Frontal: A Basic Face Image Type that adheres to additional requirements appropriate for frontal face
recognition and/or human examination. Two types of Frontal Face Image Types are defined in this
document, Full Frontal and Token Frontal (or simply Token).
 Full Frontal: A Face Image Type that specifies frontal images with sufficient resolution for human
examination as well as reliable computer face recognition. This type of Face Image Type includes the full
head with all hair in most cases, as well as neck and shoulders. This image type is suitable for permanent
storage of the face information, and it is applicable to portraits for passport, driver license, and “mugshot”
images.
 Token Frontal: A Face Image Type that specifies frontal images with a specific geometric size and eye
positioning based on the width and height of the image. This image type is suitable for minimizing the
storage requirements for computer face recognition tasks such as verification while still offering vendor
independence and human verification (versus human examination which requires more detail) capabilities.
Table 1 shows the relationships between Face Image Types using the notion of inheritance. For example,
Frontal inherits properties from Basic, which means that all normative clauses that apply to Basic also apply to
Frontal.
Table 1 – Inheritance of Face Image Types
Face Image Type Inherits from Normative clauses Informative clauses
Basic None 1, 2, 3, 4, 5, 6 A.1
Frontal Basic 7 A.2
Full Frontal Frontal 8 A.3
Token Frontal 9 A.4
Figure 1 gives a general overview of the scene, photographic, digitization, and format requirements for the
face image types specified in this part of ISO/IEC 19794.
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ISO/IEC 19794-5:2005(E)

Requirements
Scene Photographic Digital Format
Digital Specif
...