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4 OSAC 2024‐N‐0004

5 Standard Guide for Capturing

6 Iris Images for Use with Iris

7 Recognition Systems

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9 Facial & Iris Identification Subcommittee

10 Digital/Multimedia Scientific Area Committee (SAC)

11 Organization of Scientific Area Committees (OSAC) for Forensic Science

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27 OSAC Proposed Standard

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29 DRAFT OSAC 2024‐N‐0004

30 Standard Guide for Capturing Iris

31 Images for Use with Iris Recognition

32 Systems

33 

34 Prepared by  

35 Facial & Iris Identification Subcommittee

36 Version: 1.0

37 February 2024

38 

39 

40 Disclaimer:

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42 This OSAC Proposed Standard was written by the Facial & Iris Identification Subcommittee of the

43 Organization of Scientific Area Committees (OSAC) for Forensic Science following a process that

44 includes an open comment period. This Proposed Standard will be submitted to a standard

45 developing organization and is subject to change.  

46 There may be references in an OSAC Proposed Standard to other publications under

47 development by OSAC. The information in the Proposed Standard, and underlying concepts and

48 methodologies, may be used by the forensic‐science community before the completion of such

49 companion publications.

50 Any identification of commercial equipment, instruments, or materials in the Proposed Standard

51 is not a recommendation or endorsement by the U.S. Government and does not imply that the

52 equipment, instruments, or materials are necessarily the best available for the purpose.

53    

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58 1. Scope

59 1.1 This guide isintended for use by practitioners who are choosing,setting up, and operating

60 equipment designed to capture irisimagesfor use with automated Iris Recognition Systems,such

61 as Federal Bureau of Investigation’s (FBI) Next Generation Identification (NGI) Iris Service. The

62 guide also provides an overview of how to achieve the specifications defined in the relevant

63 standards as listed below.

64 1.2 This document provides guidance for proper collection and management of iris images

65 captured in well controlled environments, (e.g., booking stations), and semi‐controlled

66 environments (e.g., field capture).

67 1.3 This document provides equipment guidance for capturing irisimagesin the near‐infrared

68 (near‐ir) region of the electromagnetic spectrum from approximately 700 nm to 900 nm.  It does

69 not address visible light spectrum (from 380 to 700 nanometers) images or video captured via

70 conventional cameras.

71 1.4 This standard does not purport to address safety concerns, if any, associated with its use.

72 It is the responsibility of the user of this standard to establish appropriate safety and health

73 practices and determine the applicability of regulatory limitations prior to use.

74 2. Referenced Documents

75 2.1 Biometric Standards:

76 2.1.1 ANSI/NIST‐ITL‐1‐2011 Update 2015: Data Format for the Interchange of Fingerprint, Facial

77 and Other Biometric Information

78 2.1.2 ISO/IEC 29794‐6:2015 ‐ Information Technology ‐ Biometric sample quality ‐ Part 6:  Iris

79 image data
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80 2.1.3 NIST Interagency Report 8013:  IREX V Guidance for Iris Image Collection

81 2.1.4 NIST Special Publication 500‐280 – Mobile ID Device Best Practice Recommendation

82 Version 1.0 (Section 8)

83 2.1.5 NIST TN‐2018:  Standards Relevant for Iris Camera Acquisitions

84 3. Terminology

85 3.1 Definitions:  

86 3.2 Canthus, n: plural canthi. The corner at each side of the eye where the upper and lower

87 eyelids join.  

88 3.2.1 Discussion: The medial (sometimes called inner) canthus is adjacent to the nose; the

89 lateral (sometimes called outer) canthus is adjacent to the temple.

90 3.3 Iris texture, n:  the totality of features that can be captured in an image of an iris; these

91 features can be used for identification.

92 3.4 Near‐infrared wavelength spectrum, n: in the context of this document, 700 to 900

93 nanometers; the range of wavelength recommended in ISO standards for use in iris recognition

94 cameras.

95 3.5   Specular reflection, n:  reflections of a scene off the outer and inner surfaces of the eye.

96 3.5.1   Discussion:  Specular reflections create false features on the iris that negatively impact

97 recognition accuracy. They typically show what isin front of the subject and result from improper

98 ambient lighting.

99 3.6   Visible light spectrum, n:  in the context of this document, 300 to 700 nanometers; the

100 range of wavelengths used in conventional photography.

101 
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102 4. Significance and Use

103 4.1 Image quality is a critical factor in the performance of iris recognition systems and the

104 performance of iris image examiners.

105 4.2 Many iris images are submitted to a database in an ANSI‐NIST ITL‐1100 Electronic

106 Biometric Transmission Specification (EBTS) file. The images extracted from the cameras may

107 have to be processed through a middleware to be formatted correctly prior to adding to the

108 EBTS file. The image must not be lossy compressed at any stage of the process and should be

109 saved in a lossless compression format.

110 4.3 For the purpose of this discussion, image quality factors may be characterized into the

111 following categories:

112 4.3.1 Subject characteristics:  characteristics that affect the visibility of the iris texture;  these

113 include eyelid opening and eyelash length, subject capability to present an on axis, well aligned

114 image.  

115 4.3.2 Ambient environment: factors that can affect the iris camera or the subject; these

116 include brightness of visible light which can affect the subject’s pupil dilation and the presence

117 of extraneous near‐ir light sources, such as sunlight, that can generate specular reflections that

118 will be seen in the near‐ir images collected by the iris camera.

119 4.3.3 Iris camera:  camera characteristics including depth of focus, field of view, single eye vs.

120 dual eye, operator interface.

121 4.3.4 Operator skill:  the best camera can take poor images of a good subject when not used

122 according to best practice for the camera.

123 5. Scenarios

124 5.1 Controlled acquisition
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125 5.1.1 This scenario is when all constraints can be controlled including image capture

126 equipment, the capture environment and the pose and positioning of the subject.  An example

127 scenario is the well controlled booking process at a criminal justice facility.

128 5.2 Semi‐controlled acquisition

129 5.2.1 Thisscenario refersto when some, but not all, constraints can be controlled. An example

130 is law enforcement mobile capture. In these situations, ambient conditions may not be well

131 controlled, the level of subject cooperation may be diminished, and other conditions may create

132 additional stress on the operator.

133 5.3 See Figures X and Y for examples of good and poor iris image captures in both controlled

134 and semi‐controlled environments and mitigation strategies.

135 5.4 Automated image quality assessment may be built into cameras.    It is strongly

136 recommended that image quality is assessed at the time of capture to provide immediate

137 feedback to the camera operator.  

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146 ANNEX

147 (Mandatory Information)

148 A1.  TABLES

149 1A1.1 Important environmental factors when capturing iris images)

No. Item Description Comments

1 Ambient

Illumination

Ambient lighting with illumination

of typical office space levels shall

be utilized.

Areas with direct or indirect

sunlight should be avoided.

Bright incandescent lighting should

be avoided.

Dark rooms should be avoided

unless the iris capture device  

provides its own source of visible

illumination.  

2 Camera

position

As recommended by the camera

manufacturer.

Ensure the operator’s fingers are

not obscuring any part of the

camera lens or illumination array.

150 

151 1A1.2 Important factors regarding subject pose

No. Item Description Comments

1 Subject

position

The subject should remain still

with the eye gaze directed

towards the camera axis with the

head position square to the

camera sensor.  

Eye gaze angle is a specific image

quality metric.

2 Glasses The subject shall remove glasses

prior to image capture for

enrollment scenarios.

Glasses may obstruct portions of

the eye due to specular highlights,

scratches or dirt on the surface of

the lens.

3 Contact

lenses

Contact lenses obscuring the iris

texture (e.g. patterned cosmetic

lenses) shall be removed prior to

image capture.   

Iris images shall not be captured if

the subject cannot remove

patterned cosmetic contact lenses.
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Clear contact lenses not obscuring

the iris texture need not be

removed.

5 Distance The minimum distance between

the iris capture device’s lens and

the subject’s eye  is typically 100

millimeters.

This distance is acceptable as non‐

intrusive and avoids excessive

geometric distortion.

6 Occlusion Minimize anything (hair, fake

eyelashes) that would obstruct

the iris texture.

The subject may use their fingers

to open the eyes wider if the iris is

obscured.

152    

153 1A1.3 Important factors regarding capture device

No. Item Description Comments

1 Camera type Cameras capable of capturing

images in the near‐ir wavelength

shall be used.  Conventional

visible full‐spectrum image

capture should not be used.

The camera shall meet “ISO/IEC

29794‐6:2015 Information

technology — Biometric

sample quality ‐ Part 6: Iris image

data.”

Iris images are captured in non‐

visible wavelengths, making them

different from images taken using

a conventional camera.   

These images also have markedly

different data storage and

transmission requirements.

2 Color space Monochrome near‐iror near‐ir

channel of a color sensor: Near‐

infrared wavelength bandwidth

(approximately 700 to 900 nm.)

shall be used.  

Illumination shall be compliant

with illumination standard IEC

608251‐1 and safety specification

ISO 62471‐ 1 "Exempt" category

(i.e., eye safe in all circumstances).

3 Capture Devices used for capture of iris

images should capture both left

and right images  simultaneously

or quasi‐simultaneously (within a

few milliseconds).

This reduces the possibility of

mislabeling the individual images

(right or left) while also allowing

more accurate estimation of the

roll angle and potentially higher

accuracy and comparison speed.
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If not mounted, the iris camera

should include an orientation

sensor prohibiting the iris capture

process if the device is upside

down.

4 Failure to

Acquire

(FTA)

For fully cooperative subjects, the

FTA rate should be below a level

which is acceptable for a specific

scenario.

Failure to acquire occurs when the

device is unable to acquire an

image required in a specific

scenario within a specified time

out period.

5 Compressio

n

Iris images from a device must be

uncompressed or losslessly

compressed.   

6 Image

Format

The device must supply images in

a standard format suitable for use

by matching and encoding

systems.  (e.g., bmp, png)

The image format should be

compatible with middleware of the

applicable system.

7 Image

Quality

Metrics

Image quality and consistency

have a direct impact on matching

capability.  

The camera should encourage

operator behavior that will

generate images that are ISO/IEC

29794‐6:2015 compliant.  

Examples of compliant and non‐

compliant images are seen in Fig. Y

of this document.

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159 FIG. X Example of a Good Quality Iris Image

160 https://www.nist.gov/document/irexvslides20140612pptx
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162 FIG. Y Examples of Good and Poor Image Captures

163 https://www.nist.gov/system/files/d