1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBiometrics Interoperability profiles Best Practices for slap tenprint capturesPD CEN/TS 16428:2012National forewordThis Published Document is the UK implementation of CEN/TS 1642
2、8:2012. The UK participation in its preparation was entrusted to Technical CommitteeIST/17, Cards and personal identification.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
3、 a contract. Users are responsible for its correct application. The British Standards Institution 2012.Published by BSI Standards Limited 2012 ISBN 978 0 580 78343 2 ICS 35.240.15Compliance with a British Standard cannot confer immunity from legal obligations.This Published Document was published un
4、der the authority of the Standards Policy and Strategy Committee on 30 November 2012.Amendments issued since publicationDate Text affectedPUBLISHED DOCUMENTPD CEN/TS 16428:2012TECHNICAL SPECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 16428 October 2012 ICS 35.240.15 English Vers
5、ion Biometrics Interoperability profiles - Best Practices for slap tenprint captures Interoprabilit des profils biomtriques - Recommandations pour la capture de dix empreintes digitales plat Profile fr die biometrische Interoperabilitt - Optimales Vorgehen bei Erfassung aller Finger mittels gleichze
6、itigem Auflegen This Technical Specification (CEN/TS) was approved by CEN on 27 August 2012 for provisional application. The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the quest
7、ion whether the CEN/TS can be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standard
8、s in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Mace
9、donia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUR
10、OPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 16428:2012: EPD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 2 Contents Page Foreword 31 Scope 42 S
11、ensor hardware requirement 53 Acquisition software .54 Logging and evaluation of data 75 Operational process 96 Operational issues 12Annex A (informative) Example of acquisition process . 15Annex B (informative) Example of an acquisition process based on composite records 16Annex C (informative) Exa
12、mple of a quality metric for the acquisition process . 19Bibliography . 20PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 3 Foreword This document (CEN/TS 16428:2012) has been prepared by Technical Committee CEN/TC 224 “Personal identification, electronic signature and cards and their related systems and
13、operations”, the secretariat of which is held by AFNOR. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC I
14、nternal Regulations, the national standards organisations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Ic
15、eland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 4 1 Scope The main goal of this Technical Specification is to give gui
16、delines to follow during the acquisition process of slap tenprints in order to obtain fingerprints with the best quality possible in acceptable time constraints. NOTE Non-cooperative users are out of the scope of this Technical Specification. When using ten-fingerprint sensors, it is fundamental to
17、know how to use them and how to proceed during the acquisition. This Technical Specification describes how to capture fingerprints correctly by specifying best practices for slap ten-print captures. This Technical Specification gives guidance on the following topics: 1) Recommendations on the hardwa
18、re of the fingerprint sensor and its deployment, 2) Recommendations on user guidance, 3) Recommendations on the enrolment process including a sample workflow, 4) Recommendations for developers and system integrators on application software, 5) Recommendations on processing, compression and coding of
19、 the acquired fingerprint images, 6) Recommendations on operational issues and data logging, 7) Recommendations on the evaluation of a solution and its components. Although this Technical Specification primarily focuses on reaching optimal data quality for enrolment purposes, the recommendations giv
20、en here are applicable for other purposes. All processes which rely on good quality tenprint slaps can take advantage of the best practices reported here. PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 5 2 Sensor hardware requirement Image quality should comply with the quality specifications from ISO/IE
21、C 19794-4:2011 1. EBTS/F corresponds to Annex B.1 and BSI TR-03121 corresponds to Annex B.3 of ISO/IEC 19794-4:2011 1. NOTE 1 This Technical Specification considers optical sensors based on the principle of total internal reflection. However, this does not mean that other technologies cannot be used
22、 for tenprint enrolment purposes. As soon as sufficient experiences are available and recommendations can be given on emerging technologies, they will be included in a future version of this document. The sensor device should provide methods for re-calibration in the field by qualified service staff
23、 if the device technically supports it. It is recommended that the compliance of a sensor device to the applicable quality standard can be verified at any time in the operational environment. NOTE 2 The need for calibration or re-calibration depends on the sensor technology and calibration might not
24、 be necessary for all devices. 3 Acquisition software 3.1 Acquisition process For the acquisition process, the highest quality images should be used. The acquisition of these images should be done automatically. The sequence of images having the highest quality should be used; if a timeout has occur
25、red then these may be below the desired quality levels. An example for an acquisition process design can be found in Annexes A and B, an example for a quality metric can be found in Annex C. 3.2 User feedback The presence of a user interface is strongly advised to give feedback to the user. Feedback
26、 can be given, for example, by: A screen attached in close neighbourhood to the sensor, Illuminated pictograms on the sensor, LEDs assigned to pictograms directly on the sensor. The following information should be given to the user: Assistance to finger positioning with images and/or video on the sc
27、reen and/or audio instructions (for instance to instruct the user to move its fingers to the left/right/top/bottom), Visual and/or audio notification when a successful acquisition has been completed, A Quality indicator for each acquisition. This indicator should be simple, for example a two-state l
28、ogic (not good/good) or similar, If possible, the reason for a bad quality acquisition (e.g. wrong positioning of the hand). PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 6 Additional information (e.g. a poster or a video) can be used to illustrate to users how to use the system. This information can be
29、 displayed close to the sensor and additionally in the waiting zone. Operators should be trained to give guidance to the users. 3.3 Acquisition check The software linked to the sensor should take account of the following during the acquisition process in order to perform a better acquisition: Any fe
30、edback provided by the sensor software (background correction, quality evaluation, end of acquisition, etc.), A timeout for capturing the best available image in case the specified quality threshold is not reached, The inability of the subject to provide a full set of fingerprints. Acceptable images
31、 for certain fingers may not have been captured. This can be due to missing fingers, inability for the subject to interact with the sensor correctly, temporary or permanent issues with the subjects fingerprints. The image quality of the captured images. This is to enable the system to finish the acq
32、uisition process after the preset quality level or a timeout has been reached, The subjects fingers have been removed from the sensor at the end of the acquisition process, All two consecutively captured slaps and captured thumbs are not identical. A duplicate check should also be performed to ensur
33、e that all expected fingers have been captured once and once only, NOTE Due to computational time constraints this recommendation could also be enforced by the operator instead of the software. Residual traces have not been acquired, The fingerprint images are as originally acquired. Optionally, seg
34、mented images can be produced, Hand inversion between left and right slap has not occurred. This check can be based on the different physical characteristics of the shapes of both hands. 3.4 Image processing 3.4.1 Segmentation Independently of physical resolution of the sensor and the image acquired
35、, the resolution of the fingerprint image should be at least 197 ppcm (500 ppi) and, therefore, can differ from the scan resolution. Depending on the call to capture one, two, three or four fingerprints, this number of individual fingerprints should be extracted from the input image and provided as
36、single fingerprints generated by a segmentation process which takes into account fingers reported to be missed. PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 7 For this segmentation process, the following criteria should be fulfilled: Ability to accept rotated fingerprints having the same direction in a
37、n angle up to 45 Rotated fingerprints having the same direction should be corrected to be vertical Segment the first part over the finger (first phalanx) Segmentation should be performed on uncompressed data. Recommended size for fingerprint images is given in ISO/IEC 19794-4:2011, D.1. NOTE Size li
38、mitation is done in order to prevent performance issues. 3.4.2 Compression Fingerprint images should be compressed according to the recommendations in ISO/IEC 19794-4:2011, section 8.3.17 “Image compression algorithm”. NOTE 1 The compression ratio should not be too high, a maximum compression ratio
39、of 15 is recommended. NOTE 2 The WSQ compression is mainly used for fingerprint compression; it has been optimized to be compatible with minutiae calculation. The implementation of the used WSQ algorithm should be certified by the FBI and should be referenced by the respective certificate number (co
40、ded in the WSQ header). Multiple lossy compressions should be avoided as they harm image quality. 4 Logging and evaluation of data 4.1 General Logging and evaluation data might be subject to European Union or national legal constraints and should be handled accordingly. 4.2 Logging data The purpose
41、of the logging data is not to track people but to give guidance to the staff in charge of the enrollment and to maintain a constant quality of the acquisition process. The following data, or parts of it, should be logged: Transaction ID Timestamp of acquisition Duration of biometric acquisition proc
42、ess Number of captured images Number of successful captures Quality scores for all captured fingerprints Overall quality score of captured slap or ten prints sets (if present) PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 8 Information about vendor, software, hardware and versions Information about the
43、origin (e.g. Agency Identifier) Information about errors (e.g. about uniqueness check, segmentation, etc) Size of acquired data Testing flags (if applicable) Demographic data on the subject (gender, age). NOTE It might be appropriate to have a regular logging workflow and an evaluation mode logging
44、workflow with more comprehensive logging data. The latter one could be used for regular or incident-based checks of the whole process. When used in a verification or identification scenario, it is recommended to also log results of the verification and identification process. 4.3 Useful statistical
45、evaluations Conducting regular (e.g. every month, every three month, every year) evaluations on the acquired logging data is recommended. As a minimum, the following basic set of evaluations should be conducted: Quality scores distribution Error code distribution Average enrolment duration Distribut
46、ion of enrolment duration Distribution of gender and age, especially in relation to quality scores When used in a verification or identification scenario, it is recommended to also evaluate the accumulated results of the verification or identification attempts. PD CEN/TS 16428:2012CEN/TS 16428:2012
47、(E) 9 5 Operational process 5.1 General user guidance The presence of a user interface is strongly advised to support better acquisition. The following placement recommendations should be applied: The user should set down the fingers flat on the sensor and in particular their tips but not set down o
48、nly the tips (see Figure 1) or the sides of the fingers (see Figure 2). Figure 1 Tips of the fingers Figure 2 Sides of the finger The user should position his fingers straight, parallel to the edges of the sensor (see Figure 3) and avoid any rotation unless a rotation is the only way to place all fi
49、ngers on the acquisition surface of the sensor (see Figure 4). Figure 3 Prefer parallel fingers in relation to the edges Figure 4 Avoid rotated fingers in relation to the edges PD CEN/TS 16428:2012CEN/TS 16428:2012 (E) 10 The user should position the thumb(s) straight, parallel to the edges of the sensor (see Figure 5) and avoid any rotation. Figure 5 Correct thumbs position Figure 6 Wrong thumbs position The user should p
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