ISO/IEC 19794-5:2011

Information technology — Biometric data interchange formats — Part 5: Face image data

ISO/IEC 19794-5:2011 specifies a record format for storing, recording, and transmitting information from one or more facial images or a short video stream of facial images, specifies scene constraints of the facial images, specifies photographic properties of the facial images, specifies digital image attributes of the facial images, and provides best practices for the photography of faces.

Technologies de l'information — Formats d'échange de données biométriques — Partie 5: Données d'image de la face

General Information

• Status: Published
• Publication Date: 02-Nov-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
• Start Date: 06-Sep-2024
• Completion Date: 30-Oct-2025

Relations

• Amended By: ISO/IEC 19794-5:2011/Amd 1:2014 - Information technology — Biometric data interchange formats — Part 5: Face image data — Amendment 1: Conformance testing methodology and clarification of defects
• Effective Date: 17-Jul-2021
• Amended By: ISO/IEC 19794-5:2011/Amd 2:2015 - Information technology — Biometric data interchange formats — Part 5: Face image data — Amendment 2: XML encoding and clarification of defects
• Effective Date: 14-Oct-2020
• Revises: ISO/IEC 19794-5:2005/Amd 2:2009 - Information technology — Biometric data interchange formats — Part 5: Face image data — Amendment 2: Three-dimensional face image data interchange format
• Effective Date: 12-Nov-2011
• Revises: ISO/IEC 19794-5:2005 - Information technology — Biometric data interchange formats — Part 5: Face image data
• Effective Date: 15-Apr-2008
• Revises: ISO/IEC 19794-5:2005/Amd 1:2007 - Information technology — Biometric data interchange formats — Part 5: Face image data — Amendment 1: Conditions for taking photographs for face image data
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 19794-5
Second edition
2011-11-01
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 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,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
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ii © ISO/IEC 2011 – All rights reserved

Contents Page
Foreword . v
Introduction . vi
1  Scope . 1
2  Conformance . 1
3  Normative references . 2
4  Terms and definitions . 2
5  The Face Image Data Record Format . 4
5.1  Overview . 4
5.2  Data Conventions . 7
5.3  The General Header . 8
5.4  The Representation Header . 9
5.5  The Facial Information Block . 11
5.6  The Landmark Point Block . 16
5.7  The Image Information Block . 22
5.8  The Representation Data block . 25
5.9  The Image Data Block . 25
5.10  The 3D Information Block . 25
5.11  The 3D Data Block . 32
6  The Basic Face Image Type . 35
6.1  Inheritance requirements for the Basic Face Image Type . 35
6.2  Image data encoding requirements for the Basic Face Image Type . 35
6.3  Image data compression requirements for the Basic Face Image Type . 35
6.4  Format requirements for the Basic Face Image Type . 35
7  The Frontal Face Image Type . 35
7.1  Inheritance requirements for the Frontal Face Image Type . 35
7.2  Scene requirements for the Frontal Image Type . 36
7.3  Photographic Requirements for the Frontal Image Type . 37
7.4  Digital requirements for the Frontal Image Type . 38
7.5  Format requirements for the Frontal Image Type . 39
8  The Full Frontal Image Type . 39
8.1  Inheritance requirements for the Full Frontal Face Image Type . 39
8.2  Scene requirements for the Full Frontal Face Image Type . 39
8.3  Photographic requirements for the Full Frontal Face Image Type . 40
8.4  Digital requirements for the Full Frontal Face Image Type . 42
8.5  Format requirements for the Full Frontal Image Type . 42
9  The Token Face Image Type . 42
9.1  Inheritance requirements for Token Face Image Type . 42
9.2  Digital requirements for the Token Face Image Type . 42
9.3  Format requirements for the Token Face Image Type . 44
10  The Post-processed Frontal Face Image Type . 44
10.1  Introduction . 44
10.2  Inheritance requirements for the Post-processed Frontal Face Image Type . 44
10.3  Format requirements for the Post-processed Frontal Face Image Type . 44
11  The Basic 3D Image Type . 45
11.1  Inheritance Requirements for the Basic 3D Image Type . 45
11.2  The Basic 3D Image Type using the 3D Point Map representation . 45
© ISO/IEC 2011 – All rights reserved iii

11.3  The Basic 3D Image Type using the 3D Vertex representation .45
12  The Full Frontal 3D Image Type .45
12.1  Inheritance requirements .45
12.2  Coordinate System Type .46
12.3  Pose of the 3D representation .46
12.4  Calibration Texture Projection Accuracy .46
12.5  Requirements on Full Frontal 3D Image Types using the Range Image Representation .46
12.6  Requirements on Full Frontal 3D Image Types using the 3D Point Map Representation .47
12.7  Requirements on Full Frontal 3D Image Types using the 3D Vertex Representation .47
13  The Token Frontal 3D Image Type .47
13.1  Inheritance requirements .47
13.2  Requirements on Token Frontal 3D Image Types using the Range Image Representation .48
13.3  Requirements on Token Frontal 3D Image Types using the 3D Point Map Representation.48
13.4  Requirements on Token Frontal 3D Image Types using the Vertex Representation .48
14  Registered Format Type Identifier .48
Annex A (normative)  Conformance test methodology .49
Annex B (informative) Best practices for Face Images .50
Annex C (informative) Conditions for Taking Photographs .70
Annex D (informative) Experimental studies . 100
Annex E (informative) The Frankfurt Horizon . 110
Bibliography . 111

iv © ISO/IEC 2011 – All rights reserved

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 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.
This second edition constitutes a technical revision of the first edition (ISO/IEC 19794-5:2005), which is
provisionally retained. It also incorporates the Amendments ISO/IEC 19794-5:2005/Amd.1:2007 and
ISO/IEC 19794-5:2005/Amd.2:2009, and the Technical Corrigenda ISO/IEC 19794-5:2005/Cor.1:2008 and
ISO/IEC 19794-5:2005/Cor.2:2008. This edition reflects the harmonization across the second generation of
ISO/IEC 19794. Clause 5 contains descriptions of the harmonized general and representation headers; and
Clauses 5 to 13 have been technically revised. Annexes C, D, and E have been added.
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
© ISO/IEC 2011 – All rights reserved v

Introduction
Face images, also commonly referred to as displayed portraits, have been used for many decades to verify
the 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 for passports and driver licenses, there is a need 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 identity by comparison of persons against facial images,
3) computer automated face biometric identification (one-to-many searching), and
4) computer automated face biometric verification (one-to-one comparison).
To enable many applications on a variety of devices, including devices that have limited resources available
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.) and digital image attributes (image resolution, image size, etc.).
Several face image types are introduced to define categories that satisfy requirements of some applications:
 Basic: This is the fundamental Face Image Type that specifies a record format including header and
representation 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
part of ISO/IEC 19794, 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.
 Post-processed Frontal: Applying digital post-processing to a captured image can modify this image
in a way that it is more suitable for automatic face recognition. The Post-processed Frontal Face
Image Type is thought of as the interchange format for these kinds of facial images.
 Basic 3D: The Basic 3D Image Type is the base Image Type of all 3D Face Image Types. All 3D
Face Image Types obey normative requirements of this image type.
 Full Frontal 3D: The Full Frontal 3D Image Type combines a Full Frontal 2D image with additional 3D
information.
 Token Frontal 3D: The Token Frontal 3D Image Type combines a Token Frontal 2D image with
additional 3D information.
vi © ISO/IEC 2011 – All rights reserved

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 annexes
Basic None 1, 2, 3, 4, 5, 6 B.1
Frontal Basic 7 B.2
Full Frontal Frontal 8 B.3
Token Frontal Frontal 9 B.4
Post-processed Frontal Frontal 10

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.
Requirements
Scene Photographic Digital Format

Digital Specifications
Positioning Digital Camera
Lighting
Record Format and
Organization
Camera Attributes
Image and Subject
Analogue to Digital
Image Scanning
Clauses: Clauses: Clauses: Clauses:
Basic Face None Basic Face
None Basic Face None Basic Face 5
6.2
6.3
6.4
Frontal Face 7.2 Frontal Face 7.3 Frontal Face 7.4 Frontal Face 7.5
Full Frontal Face 8.2 Full Frontal Face 8.3 Full Frontal Face 8.4 Full Frontal Face 8.5
Token Face 9.2 Token Face 9.3
Post-processed 10.3
Frontal Face
Figure 1 — The types of imaging requirements specified in this part of ISO/IEC 19794. The Basic Face
Image Type has no scene, photographic, or digital requirements
© ISO/IEC 2011 – All rights reserved vii

This is a revision of ISO/IEC 19794-5:2005. The structure of the data format is not compatible with the
previous version.
NOTE This part of ISO/IEC 19794 relies on other ISO International Standards.

viii © ISO/IEC 2011 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 19794-5:2011(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 or a short video stream of facial images,
 specifies scene constraints of the facial images,
 specifies photographic properties of the facial images,
 specifies digital image attributes of the facial images,
 provides best practices for the photography of faces.
2 Conformance
A biometric data record conforms to this part of ISO/IEC 19794 if it satisfies all of the normative requirements
related to:
A) Its data structure, data values and the relationships between its data elements, as specified in Clauses 5, 6,
7, 8 for the Full Frontal Face Image Type, Clauses 5, 6, 7, 9 for the Token Frontal Image Type, and Clauses 5,
6, 7, 10 for the Post-processed Frontal Image Type of this part of ISO/IEC 19794, respectively.
B) The relationship between its data values and the input biometric data from which the biometric data record
was generated, as specified in Clauses 5, 6, 7, 8 for the Full Frontal Face Image Type, Clauses 5, 6, 7, 9 for
the Token Frontal Image Type, and Clauses 5, 6, 7, 10 for the Post-processed Frontal Image Type of this part
of ISO/IEC 19794, respectively.
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 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 Implementation Conformance Statement.
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 Implementation Conformance Statement 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 Implementation
Conformance Statement.
© 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 10918-1, Information technology — Digital compression and coding of continuous-tone still images:
Requirements and guidelines
ISO/IEC 14496-2:2004, Information technology — Coding of audio-visual objects — Part 2: Visual
ISO/IEC 15444-1, Information technology — JPEG 2000 image coding system: Core coding system
ISO/IEC 15948, Information technology — Computer graphics and image processing — Portable Network
Graphics (PNG): Functional specification
ISO/IEC 19794-1:2011, Information technology — Biometric data interchange formats — Part 1: Framework
ISO/IEC 29794-1, Information technology — Biometric sample quality — Part 1: Framework
4 Terms and definitions
For the purposes of this document, the terms and definitions as well as abbreviated terms given in
ISO/IEC 19794-1 and the following apply.
4.1
2D image
two-dimensional face representation that encodes the luminance and/or colour texture of a capture subject in
a given lighting environment
4.2
3D image
three-dimensional face representation that encodes a surface in a 3D space
4.3
3D point map
3D point cloud representing a capture subject, where each surface point is encoded with a triplet, representing
the x, y and z value of the point in 3D respectively
4.4
3D vertex representation
representation using 3D vertices and triangles between these points for coding of a 3D surface
4.5
anthropometric landmark
landmark point on the face used for identification and classification of humans
4.6
anthropometric landmark code
two-part code that defines an anthropometric landmark uniquely
4.7
Cartesian coordinate system
3D orthogonal coordinate system
4.8
chin
central forward portion of the lower jaw
2 © ISO/IEC 2011 – All rights reserved

4.9
colour image
continuous-tone image that has more than one channel, each of which is coded with one or multiple bits
4.10
colour space
way of representing colours of pixels in an image
EXAMPLE RGB, YUV and greyscale colour spaces are typically used in this part of ISO/IEC 19794.
4.11
crown
top of the head, or (if obscured by hair or headwear) where the top of the head/skull would be if it could be
seen
4.12
cylindrical coordinate system
three-dimensional polar coordinate system describing a point by the three components radius, azimuth and
height
4.13
dots per inch (DPI)
measurement of scanner and printer spatial sampling rate
4.14
facial image
electronic image-based representation of the portrait of a person
4.15
face image type
category of facial images that satisfy specific requirements
4.16
feature point
reference point in a face image as used by face recognition algorithms
NOTE Commonly referred to as a landmark, an example being the position of the eyes.
4.17
fish eye
type of distortion where central objects of the image erroneously appear closer than those at the edge
4.18
greyscale image
continuous-tone image encoded with one luminance channel
NOTE For example, if the luminance channel is coded with 8 bits, the greyscale image is also referred to as a
monochrome or black and white image.
4.19
human examination
process of careful human comparison of a face image with a person or another face image to ascertain the
identity of the respective person by a detailed examination of facial characteristics and structures
4.20
human verification
validation of the identity of a face image by means of comparison with a person or other face image
NOTE Also known as one-to-one (1:1) comparison.
© ISO/IEC 2011 – All rights reserved 3

4.21
JPEG
image compression standard specified as ISO/IEC 10918-1
NOTE The JPEG baseline standard was published as ISO/IEC 10918-1 and ITU-T Rec. T.81.
4.22
JPEG2000
image compression standard specified as ISO/IEC 15444-1
NOTE The JPEG2000 baseline standard was published as ISO/IEC 15444-1 and ITU-T Rec. T.800.
4.23
PNG format
lossless image compression standard specified in ISO/IEC 15948
4.24
portrait
photograph of a person which includes the full head, with all hair in most cases, as well as neck and top of
shoulders
4.25
range image
numerical matrix that encodes a surface point in 3D space, where the position encodes the first two
coordinates and the value at that position encodes the third coordinate
4.26
red-eye
red glow from a subject's eye caused by light from flash reflecting from blood vessels behind the retina
4.27
texture
two-dimensional representation of the luminance and/or colour of a capture subject in a given lighting
environment
4.28
texture projection matrix
3x4 matrix to transform a 3D surface coordinate from a metric Cartesian coordinate system to a 2D texture
image coordinate, where the transformation makes use of the 3D homogeneous coordinates of the 3D point
as well as the 2D homogeneous coordinates of the 2D point
NOTE See reference [2] for details.
5 The Face Image Data Record Format
5.1 Overview
The ISO/IEC 19794-5 BDIR format specified in this part of ISO/IEC 19794 is a format to store face
representations within a biometric data record. Each BDIR shall pertain to a single subject and shall contain at
least one or more 2D image and zero or more geometric representations (range images, 3D point maps, 3D
vertex representations) of a human face. Depending on the face image type, a 3D representation of a face
may be included in addition to the 2D representation. The record structure is depicted in Figure 2,
and Figure 3.
Adherence to this format requires compliance to the standards referred to above. In particular, 2D image data
will be encoded using JPEG, JPEG2000 or PNG.
4 © ISO/IEC 2011 – All rights reserved

When referring to elements of the record format, “field” denotes the singular element such as Face Image
Type and Image Data Type, “block” denotes the group of fields such as Facial Information block or Image
Information block, and “record” denotes the data that consists of the General Header and one or more
Representations.
Figure 2 — The ISO/IEC 19794-5 Biometric Data Interchange Record. The length value of each field in
bytes is shown below the field. The white boxes indicate fields or blocks that shall be specified, and
dark grey boxes indicate optional fields.
© ISO/IEC 2011 – All rights reserved 5

Length of 3D 3D Capture 3D Capture 3D to 2D 3D to 2D
Coordinate Texture ScaleX, OffsetX, Reserved 3D Capture 3D
3D 3D 2D Texture
3D Device
Data Device Image Texture Texture Map Texture Map
System Projection ScaleY, OffsetY, Representation Supplemental for Future Device Type Acquisition Acquisition
Represen- Technology Vendor Temporal Temporal Type Spectrum
Information Type Data Time
Type Matrix ScaleZ OffsetZ Use Identifier Time
tation Synchronicity Synchronicity
Identifier Identifier
4 1 48 12 12 48 1 1 1 1 2 2 2 2 2 2 1 1
Range
3D Data Range
Image Bit Error Map Texture Map
Image
Range Image
Depth
1 Variable Variable Variable
3D Data 3D Point 3D Point 3D Point
Error Map Texture Map
Map Width
3D Point Map Map Height Map
2 2 Variable Variable Variable
3D Data Vertex Triangle Triangle
Normal Flag Vertex Data Texture Map
Count Face Count Data
Vertex
2 4 1 Variable Variable Variable
Vertex Vertex Vertex Vertex
Vertex Data
Coordinates
Normals Errors Texture
Vertex
Vertex X Vertex Y Vertex Z
Coordinates
coordinate coordinate coordinate
2 2 2
Vertex Normals Normal X Normal Y Normal Z
2 2 2
Vertex Errors Vertex Error
Vertex Vertex
Vertex Textures
Texture X Texture Y
2 2
Triangle Triangle Triangle
Triangle Data
Index 1 Index 2 Index 3
2 2 2
mandatory,
mandatory but can be optional
unspecified
Figure 3 — The 3D Information block and the three possible 3D Data blocks specified in this part of
ISO/IEC 19794. The length value of each field in bytes is shown below the field. The white boxes
indicate fields or blocks that shall be specified, light grey boxes that the fields are mandatory, but an
unspecified value is acceptable, and dark grey boxes indicate optional fields.
With the exception of the Format Identifier and the Version Number for the standard, which are null-terminated
ASCII character strings, all data is represented in binary format.
There are no record separators or field tags; fields are parsed by byte count.
The organization of the record format is as follows:
 A fixed-length (17 byte) General Header containing information about the overall record, including the
number of facial images represented and the overall record length in bytes.
 A Representation block for each facial representation. This data consists of a Representation Header
and the Representation Data.
 The Representation Header consists of
o A fixed length (19 bytes) common elements defined in ISO/IEC 19794-1:2011
o Multiple (including none) fixed length (5 byte) Quality blocks describing the quality of the
representation.
o A fixed length (17 byte) Facial Information block describing discernable characteristics of the
subject such as gender.
o Multiple (including none) fixed length (8 byte) Landmark Point blocks describing Landmark
Points in a facial image.
o A fixed length (11 byte) Image Information block describing digital properties of the image
such as Face Image Type and dimensions such as width and height.
6 © ISO/IEC 2011 – All rights reserved

 The Representation Data consists of
o Image data consisting of a JPEG, JPEG2000 or PNG encoded data block.
o For Face Image Types containing 3D information a 3D Information block (95 byte) describing
properties of this data.
o For Face Image Types containing 3D information the 3D Data block describing the 3D shape
of the face.
Multiple 2D / 3D representations of the same biometric data subject can be described in a single record. This
is accomplished by including multiple representation blocks after the General Header block. Representation
blocks containing 2D data can be stored together with Representation blocks also containing 3D data. The
structure of this embedding is illustrated in Figure 4.

Figure 4 — Embedding multiple 2D / 3D representations in the same record

5.2 Data Conventions
5.2.1 Byte ordering
Within the record format and all well-defined data blocks therein, all multi-byte quantities are stored in Big-
Endian format. That is, the more significant bytes of any multi-byte quantity are stored at lower addresses in
th
memory than less significant bytes. For example, the value 1 025 (2 to the 10 power plus one) would be
stored as first byte= 00000100 and second byte=00000001.
5.2.2 Numeric values
All numeric values are fixed-length unsigned integer quantities, unless otherwise specified.
5.2.3 Conversion to integer
The conversion of a numeric value to integer is given by rounding down if the fractional portion is less than 0,5
and rounding up if the fractional value is greater than or equal to 0,5.
5.2.4 Unspecified field value
In Figure 2 and Figure 3 the following fields are mandatory, but the value of the field can indicate that the field
is unspecified: Capture Device Technology Identifier, Capture Device Vendor Identifier, Capture Device Type
Identifier, Gender, Eye Colour, Hair Colour, Subject Height, Property, Expression, Pose Angle, Pose Angle
Uncertainty, Image Colour Space, 3D Capture Device Technology Identifier, 3D Capture Device Vendor
Identifier, 3D Capture Device Type Identifier, 3D to 2D Image Temporal Synchronicity, 3D to 2D Texture
Temporal Synchronicity, 3D Acquisition Time, 2D Texture Acquisition Time, Texture Map Type, and Texture
Map Spectrum.
5.2.5 Unknown field value
A field value labelled by the identifier “Unknown” shall be used to denote that the information encoded by the
field cannot be determined by examination of the face image.
© ISO/IEC 2011 – All rights reserved 7

5.3 The General Header
5.3.1 Structure
The General Header block consists of seven fields; Format Identifier, Version Number, Length of Record,
Number of Representations, Capture Device Vendor Identifier, Capture Device Type Identifier and the
Temporal Semantics field as shown in Table 2.
Table 2 — The General Header
Field Size Valid values Notes
Format Identifier 4 bytes 46414300 (‘F’ ‘A’ ‘C’ 0 ) Indicates face representation data
HEX HEX
Version Number 4 bytes 30333000 (‘0’ ’3’ ’0’ 00 ) “030” in ASCII
HEX HEX
Length of Record 4 bytes 68 ≤ Length of Record ≤ 2 - 1 Includes Facial Record Header and
Facial Record Data. The minimum of
68 bytes includes the smallest JPEG
image.
Number of Representations 2 byte 1 ≤ Number ≤ 65535 See 5.3.5
Certification Flag 1 byte 00 See 5.3.6
HEX
HEX
Temporal Semantics 2 bytes 0 ≤ Number ≤ 65535 See 5.3.7 and Table 3

5.3.2 Format Identifier
The format identifier shall be recorded in four bytes. The format identifier shall consist of three characters
"FAC" followed by a zero byte as a NULL string terminator.
5.3.3 Version Number
The number for the version of ISO/IEC 19794-5 used for constructing the BDIR shall be placed in four bytes.
This version number shall consist of three ASCII numerals followed by a zero byte as a NULL string terminator.
The first and second character will represent the major version number and the third character will represent
the minor revision number. The Version Number of ISO/IEC 19794-5:2010 shall be 30333000 ; “030” –
HEX
Version 3 revision 0.
“NOTE In 2009 ISO/IEC 19794-5:2005 AMD 2 was published, which defined that interchange records that
are conformant to that amendment shall contain the version number “020”.
5.3.4 Length of Record
The length (in bytes) of the entire BDIR shall be recorded in four bytes. This count shall be the total length of
the BDIR including the general record header and one or more representation records.
5.3.5 Number of Representations
The total number of representation records contained in the BDIR shall be recorded in two bytes. A minimum
of one representation is required.
5.3.6 Certification Flag
The value shall be 00 .
Hex
NOTE No certification schemes are available for this part of ISO/IEC 19794.
5.3.7 Temporal Semantics
This two byte (2 byte) field shall be assigned according to Table 3. This supports storage of multiple
representations: from a single session (e.g. from a photo shoot); from distinct sessions (e.g. from cash
8 © ISO/IEC 2011 – All rights reserved

dispenser transactions); and from a temporal sequence (e.g. a video sequence of equally time-spaced
representations).
Table 3 — Temporal sequence flags and values
Description Value
One representation is present 0000
HEX
Two or more representations are present. The temporal relationship between them is unspecified. 0001
HEX
Two or more representations are present. The representations are taken at irregular intervals during a single 0002
HEX
session (e.g. images taken by a photographer during a shoot.)
Two or more representations are present. The representations are taken at irregular intervals spanning multiple 0003
HEX
sessions (e.g. a lifetime of passport photo submissions). Unless representation qualities are known, or some
other appropriate ordering mechanism is available, the most recent representation should be stored first.
The number of milliseconds between sequential representations (e.g. the frames extracted from a video 0004 ≤
HEX
sequence). Number <
FFFF
HEX
The representations correspond to a temporal sequence but are taken at regular intervals exceeding FFFE FFFF
HEX HEX
milliseconds.
NOTE 1 The minimum interval is 4 * 0,001 seconds = 0,004 seconds.
NOTE 2 The maximum interval is 65 534 * 0,001 seconds = 65,534 seconds.
NOTE 3 While a proper video encoding, e.g. ITU-T H264, would offer a more compact encoding of the same
sequence, it would add a decoding overhead and is anyway not supported by this part of ISO/IEC 19794.
5.4 The Representation Header
5.4.1 Structure
The Representation Header is intended to describe discrete properties of the individual discernable from the
image, one is included for each facial representation included in the record. The structure of this block is
shown in Figure 2.
The Representation Header consists of the Representation Length, the Capture Date and Time, the Capture
Device Technology Identifier, the Capture Device Vendor Identifier. These are followed by the Number of
Quality Blocks field and the related number of Quality blocks. Finally the Representation Header contains the
Facial Information block, the optional multiple Landmark Point blocks, and the Image Information block.
5.4.2 Representation Length
The (4 byte) Representation Length field denotes the length in bytes of the representation including the
representation header fields.
The minimum value of the Representation Length is 51 bytes, consisting of a minimum 47 bytes for the
Representation Header plus the size of the Representation Data, i.e. minimum 4 bytes for the Length of Image
Data Block field assuming 0 bytes for the variable data.
5.4.3 Capture Date and Time
The capture date and time field shall indicate when the capture of this representation started in Coordinated
Universal Time (UTC). The capture date and time field shall consist of 9 bytes. Its value shall be encoded in
the form given in ISO/IEC 19794-1.
5.4.4 Capture Device Technology Identifier
Capture device technology Identifier shall be encoded in one byte. This field shall indicate the class of device
technology used to acquire the captured biometric sample. A value of 00 indicates unknown or unspecified
HEX
© ISO/IEC 2011 – All rights reserved 9

technology A value of 0 indicates “unknown or unspecified”. See Table 4 for the enumerated list of possible
values.
Many different types of capture devices work in the visible spectrum or in near infra-red (NIR). To indicate that
the capture device operates in NIR the highest bit in the Capture Device Technology Identifier field shall be
set to 1. So, if the representation is a Video frame from a digital video camera operating in the visible
spectrum, the resulting value of the Capture Device Technology Identifier field shall be 06 , if it operates in
HEX
NIR, the code shall be 86 .
HEX
Table 4 — Capture Device Technology Identifier codes
Description Value
Unknown or Unspecified 00
HEX
Static photograph from an unknown source 01
HEX
Static photograph from a digital still-image camera 02
HEX
Static photograph from a scanner 03
HEX
Video frame(s) from an unknown source 04
HEX
Video frame(s) from an analogue video camera 05
HEX
Video frame(s) from a digital video camera 06
HEX
Reserved by SC37 for future use 07 to 7F
HEX HEX
Vendor specific 80 to FF
HEX HEX
5.4.5 Capture Device Vendor Identifier
The (2 byte) Capture Device Vendor Identifier shall identify the biometric organisation that owns the product
that created the BDIR. The capture device algorithm vendor identifier shall be encoded in two bytes carrying a
CBEFF biometric organization identifier (registered by IBIA or other approved registration authority). A value
of all zeros shall indicate that the capture device vendor is unreported.
5.4.6 Capture Device Type Identifier
The (2 byte) Capture Device Type Identifier shall identify the product type that created the BDIR. It shall be
assigned by the registered product owner or other approved registration authority. A value of all zeros shall
indicate that the capture device type is unreported. If the capture device vendor identifier is 0000 , then also
Hex
the capture device type identifier shall be 0000
Hex
5.4.7 Number of Quality Blocks
This field is followed by the number of 5 byte Quality blocks reflected by its value. A value of zero (0) means
that no attempt was made to assign a quality score. In this case, no Quality blocks are present.
NOTE According to ISO/IEC 19794-1:2011, 12.3.1, multiple Quality Blocks are considered as a Quality Record.
5.4.8 Quality Score
The (1 byte) Quality Score, as defined in ISO/IEC 29794-1, shall be a quantitative expression of the predicted
verification performance of the biometric sample. Valid values for Quality Score are integers between 0 and
100, where higher values indicate better quality. A value of 255 is to handle a special case. An entry of 255
shall indicate a failed attempt to calculate a quality score. This value of Quality Score is harmonized with
ISO/IEC 19784-1, where 255 is -1.
NOTE BioAPI, unlike ISO/IEC 19794 uses signed integers
5.4.9 Quality Algorithm Vendor Identifier
To enable the recipient of the quality score to differentiate between quality scores generated by different
algorithms, the provider of quality scores shall be uniquely identified by this two-byte field. This is registered
with the IBIA or other approved registration authority.
10 © ISO/IEC 2011 – All rights reserved

5.4.10 Quality Algorithm Identifier
The (2 byte) Quality Algorithm Identifier specifies an integer product code assigned by the vendor of the
quality algorithm. It indicates which of the vendor’s algorithms (and version) was used in the calculation of the
quality score and should be within the range 1 to 65 535.
NOTE Multiple quality scores calculated by the same algorithm (same vendor Identifier and algorithm Identifier) shall
not be present in a single representation.
Table 5 summarizes the quality field. All values are fixed-length unsigned integer quantities represented in
Big-Endian format.
Table 5 — Structure of Quality blocks
Description Length Valid Note
values
Number of Quality 1 byte [0,255] This field is followed by the number of 5-byte Quality Blocks reflected by its
Blocks value.
A value of zero (0) means that no attempt was made to assign a quality
score. In this case, no Quality Blocks are present.
Quality Score 1 byte [0,100] 0: lowest
255 100: highest
255: failed attempt to assign a quality score
Quality 2 bytes [1,65535] Quality Algorithm Vendor Identifier shall be registered with IBIA or other
algorithm approved registration authority as a CBEFF biometric organization. Refer to
vendor CBEFF vendor Identifier registry procedures in ISO/IEC 19785-2.
Identifier
Quality 2 bytes [1,65535] Quality Algorithm Identifier may
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