1、BSI Standards Publication BS ISO/IEC 29794-6:2015 Information technology Biometric sample quality Part 6: Iris image dataBS ISO/IEC 29794-6:2015 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO/IEC 29794-6:2015. The UK participation in its preparation was entr
2、usted to Technical Committee IST/44, Biometrics. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British
3、Standards Institution 2015. Published by BSI Standards Limited 2015 ISBN 978 0 580 78376 0 ICS 35.040 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 20
4、15. Amendments issued since publication Date Text affectedBS ISO/IEC 29794-6:2015 Information technology Biometric sample quality Part 6: Iris image data Technologies de linformation Qualit dchantillon biomtrique Partie 6: Image diris INTERNATIONAL STANDARD ISO/IEC 29794-6 Reference number ISO/IEC 2
5、9794-6:2015(E) First edition 2015-07-01 ISO/IEC 2015 BS ISO/IEC 29794-6:2015ii ISO/IEC 2015 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2015, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in
6、any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de B
7、landonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO/IEC 29794-6:2015(E)BS ISO/IEC 29794-6:2015ISO/IEC 29794-6:2015(E)Foreword v Introduction vi 1 Scope . 1 2 Conformance . 1 3 Normative references 2 4 T erms and definiti
8、ons . 2 5 Acronyms and abbreviated terms. 3 6 Iris image quality metrics . 3 6.1 General . 3 6.2 Required iris image quality metrics computed from a single image 4 6.2.1 Usable iris area 4 6.2.2 Iris-sclera contrast . 5 6.2.3 Iris-pupil contrast . 6 6.2.4 Pupil boundary circularity 7 6.2.5 Grey scal
9、e utilisation 8 6.2.6 Iris radius . 8 6.2.7 Pupil dilation . 9 6.2.8 Iris pupil concentricity . 9 6.2.9 Margin adequacy.10 6.2.10 Sharpness 12 6.3 Recommended iris image quality metrics computed from a single image 13 6.3.1 Frontal gazeelevation .13 6.3.2 Frontal gaze-azimuth 13 6.3.3 Motion blur 15
10、 6.4 Iris image quality metrics computed from two images 15 6.4.1 Common usable iris area .15 6.4.2 Dilation constancy .15 6.4.3 Illumination similarity .16 6.5 Unified (overall) quality score 16 6.5.1 General.16 6.5.2 Computational method16 7 Iris acquisition quality 17 7.1 General 17 7.2 Dedicated
11、 illumination 17 7.2.1 Description .17 7.2.2 Units of measure .17 7.2.3 Computational method18 7.2.4 Value range/threshold .18 7.3 Modulation transfer function 18 7.3.1 Description .18 7.3.2 Units of measure .18 7.3.3 Computational method18 7.3.4 Value range/threshold .18 7.4 Spatial sampling rate 1
12、8 7.4.1 Description .18 7.4.2 Units of measure .19 7.4.3 Computational method19 7.4.4 Value range/threshold .19 7.5 Optical distortion .19 7.6 Pixel aspect ratio 19 7.6.1 Description .19 7.6.2 Units of measure .19 ISO/IEC 2015 All rights reserved iii Contents PageBS ISO/IEC 29794-6:2015ISO/IEC 29794
13、-6:2015(E)7.6.3 Computational method19 7.6.4 Value range/threshold .19 7.7 Sensor signal-to-noise ratio 19 7.7.1 Description .19 7.7.2 Units of measure .19 7.7.3 Computational method20 7.7.4 Value range/threshold .20 8 Iris image quality data record .20 8.1 Binary encoding 20 8.2 XML encoding 22 Ann
14、ex A (normative) Conformance test assertions .24 Annex B (informative) Iris image quality .25 Bibliography .29 iv ISO/IEC 2015 All rights reservedBS ISO/IEC 29794-6:2015ISO/IEC 29794-6:2015(E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnic
15、al 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 activ
16、ity. 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 commit
17、tee, ISO/IEC JTC 1. 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 document should be noted. This document was drafted in acco
18、rdance 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 and IEC shall not be held responsible for identifying any or all such patent right
19、s. 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 constitu
20、te an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The comm
21、ittee responsible for this document is ISO/IEC JTC 1, Information technology, SC 37, Biometrics. ISO/IEC 29794 consists of the following parts, under the general title Information technology Biometric sample quality: Part 1: Framework Part 4: Finger image data Part 5: Face image data (Technical Repo
22、rt) Part 6: Iris image data ISO/IEC 29794 will be prepared to accommodate new, additional parts that address other modalities specified by ISO/IEC 19794, with part numbers and titles aligning appropriately. ISO/IEC 2015 All rights reserved vBS ISO/IEC 29794-6:2015ISO/IEC 29794-6:2015(E) Introduction
23、 The assessment of biometric sample quality through the calculation of quality metrics can be used to predict the resulting identification accuracy in the framework of a given biometric system. With proper use, quality metrics can enhance the functionality of a biometric system. For example they can
24、 provide feedback regarding the integrity of collected biometric data during the enrolment or identification process. The purpose of this part of ISO/IEC 29794 is to define terms and quantitative methodologies relevant to characterizing the quality of iris images and to assess their potential for hi
25、gh confidence biometric match decisions. ISO/IEC 19784-1 and ISO/IEC 19785-1 standards allocate a quality field and specify a quality score range applicable to iris images with a qualitative foundation. ISO/IEC 19794-6 includes an informative annex covering the subject of iris image capture and prov
26、ides image quality guidelines. However, these International Standards do not contain specific content to guide the quantitative formation of iris image quality metrics or the interpretations of such metrics. This part of ISO/IEC 29794 establishes required ranges of covariate values where definitive
27、empirical data exists to justify such ranges. In other cases, ranges of covariate values are specified as non-normative recommendations. This part of ISO/IEC 29794 is structured as follows. The first five Clauses state Scope, Conformance, Normative references, Terms and definitions, and Acronyms. Cl
28、ause 6 specifies a set of quality metrics for assessing the quality of iris images. Some of the metrics are declared as normative, as their impacts on recognition rates have been quantified, while others are only informative, allowing their use as they may provide valuable information for further st
29、ages in the biometric system. Some of the metrics in Clause 6 are applicable to the analysis of single images, while others are applicable to assessing the utility of a given pair of images for mutual comparison. Clause 7 is dedicated to provide guidance to acquisition device manufacturers by defini
30、ng quality parameters that shall be considered for generating conformant iris images. Clause 8 establishes encoding of the iris image quality data record.vi ISO/IEC 2015 All rights reservedBS ISO/IEC 29794-6:2015Information technology Biometric sample quality Part 6: Iris image data 1 Scope This par
31、t of ISO/IEC 29794 establishes methods used to quantify the quality of iris images, normative requirements on software and hardware producing iris images, normative requirements on software and hardware measuring the utility of iris images, terms and definitions for quantifying iris image quality, a
32、nd standardized encoding of iris image quality. Outside the scope is performance evaluation of specific iris quality assessment algorithms. 2 Conformance An iris image shall be of sufficient utility if the measurements required by 6.2.X.3 satisfy the valid range/thresholds specified in 6.2.X.4. A pa
33、ir of images of an iris shall be of sufficient utility if the pair conforms to the requirements of 6.4. Specifically, they shall satisfy valid range/thresholds specified in 6.4.X.4 using computation method specified in 6.4.X.3. An iris image quality record shall conform to this part of ISO/IEC 29794
34、 if its structure and data values conform to the formatting requirements of Clause 8 (Iris image quality data record) and its quality values are computed using the methods specified in 6.2.X.3. Conformance to the normative requirements of Clause 8 fulfils Level 1 and Level 2 conformance as specified
35、 in ISO/IEC 19794-1:2011, Annex A. Conformance to the normative requirements of Clause 6.2.X.3 is Level 3 conformance as specified in ISO/IEC 19794-1:2011, Annex A. An iris acquisition device shall conform to this part of ISO/IEC 29794 if it conforms to the normative requirements of Clause 7. Comput
36、ation of the utility of an iris image shall conform to the requirements of 6.2, specifically the computation methods described in 6.2.X.3. Computation of the utility of the pair of images shall be assessed per normative requirements of 6.4, specifically the computation methods described in 6.4.X.3.
37、If an implementation of the metrics in this part of ISO/IEC 29794 reports an unacceptable (low) quality value for one or more quality metrics, another image of the subject should be re-captured. This should be repeated until a fully conformant image has been acquired, or it is determined that repeat
38、ed acquisitions will not yield a sufficient quality (e.g., correct enrolment) within the application time constraint. In this case, one unacceptable image is chosen and retained as the best possible candidate. INTERNATIONAL ST ANDARD ISO/IEC 29794-6:2015(E) ISO/IEC 2015 All rights reserved 1BS ISO/I
39、EC 29794-6:2015ISO/IEC 29794-6:2015(E) 3 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the r
40、eferenced document (including any amendments) applies. ISO/IEC 19794- 1:2011, Information technology Biometric data interchange formats Part 1: Framework ISO/IEC 19794-6:2011, Information technology Biometric data interchange formats Part 6: Iris image data ISO/IEC 29794-1, Information technology Bi
41、ometric sample qualityPart 1: Framework 4 T erms a nd definiti ons For the purpose of this document, the terms in ISO/IEC 19794-6:2011, ISO/IEC 29794- 1, and the following apply. 4.1 covariate variable or parameter that either directly, or when interacting with other covariates, affects iris recogni
42、tion accuracy Note 1 to entry: Synonyms are variable, explanatory variable, and quality parameter. Note 2 to entry: Accuracy might be stated in terms of false negative identification rate, false positive identification rate, false non-match rate, false match rate, failure-to-enrol rate, or failure-t
43、o-acquire rate. 4.2 defocus image impairment due to the position of the iris along the optical axis of the camera away from the plane or surface of best focus, generally resulting in reduced sharpness (blur) and reduced contrast 4.3 dep t h of f ie ld a distance range relative to the entrance apertu
44、re of a capture device over which the iris image has greater than a specified quality with respect to focus 4.4 iris centre centre of a circle approximating the boundary between the iris and the sclera 4.5 iris radius radius of a circle approximating the boundary between the iris and the sclera 4.6
45、metric quantification of a covariate using a prescribed method 4.7 modulation waveform with maximum and minimum values, max and min, 100(max-min)/(max+min)% 4.8 modulation transfer function ratio of the image modulation to the object modulation at specified spatial frequencies2 ISO/IEC 2015 All righ
46、ts reservedBS ISO/IEC 29794-6:2015ISO/IEC 29794-6:2015(E) 4.9 normalised image iris portion of the image that is mapped into doubly-dimensionless polar coordinates in which the radial coordinate between the inner and outer boundaries of the iris along any angular ray from the iris centre is normalis
47、ed to lie between 0 and 1, in order to impart both size invariance for the imaged iris and also invariance to pupil dilation 4.10 pupil centre centre of a circle approximating the boundary between the iris and the pupil Note 1 to entry: This definition gives a more robust estimate of pupil centre th
48、an the definition in ISO/IEC 19794- 6:2011 because it is less sensitive to occlusions on the iris pupil boundary. ISO/IEC 19794-6:2011 defines pupil centre as the average of coordinates of all the pixels lying on the boundary of the pupil and the iris. 4.11 segmentation process of determining, withi
49、n an image containing an iris, the boundaries between areas containing visible iris tissue and those that do not Note 1 to entry: This process is preceded by localisation of the iris, and typically followed by cropping or masking regions that are not iris tissue. 4.12 spatial sampling rate number of picture elements (pixels) per unit distance in the object plane or per unit angle in the imaging system 5 Acronyms and abbreviated terms MTF Modulation Transfer Fun
