1、Designation: E3115 17Standard Guide forCapturing Facial Images for Use with Facial RecognitionSystems1This standard is issued under the fixed designation E3115; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide is intended for use by practitioners who arechoosing, setting up, and operating photographic equipmentdesigned to cap
3、ture facial images for use with an automatedFacial Recognition System or used for manual comparisons bya trained facial examiner. This guide provides an overview ofhow to achieve the specifications defined in Annex E ofANSI/NIST-ITL-1-2011, Update 2015, for capturing facialimages.1.2 Annex E of ANSI
4、/NIST-ITL-1-2011 defines a well-controlled capture environment and subject whereas this docu-ment will give guidance where tight controls in the captureenvironment and subject control cannot be achieved.1.3 This guide addresses equipment considerations for two-dimensional (2D) conventional images. I
5、t does not addressvideo, scanners, or three-dimensional (3D) capture.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to non-SI units that are provided for informationonly and are not considered standard.1.5 This standard do
6、es not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This internatio
7、nal standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Commit
8、tee.2. Referenced Documents2.1 ASTM Standards:2E2916 Terminology for Digital and Multimedia EvidenceExamination2.2 Other Biometric Standards:ANSI/NIST-ITL-1-2011, Update 2015 Data Format for theInterchange of Fingerprint, Facial and Other BiometricInformation3NIST Special Publication 500-280v2 Mobil
9、e ID Device BestPractice Recommendation, Version 2.033. Terminology3.1 Definitions:3.1.1 For terms relating to digital and multimedia evidence,refer to Terminology E2916.3.2 Definitions of Terms Specific to This Standard:3.2.1 fish eye effect, na type of distortion, where centralobjects of the image
10、 erroneously appear closer than those at theedge typically resulting in what appear to be unusually largenoses in the image.3.3 Acronyms:3.3.1 2Dtwo-dimensional3.3.2 FRfacial recognition4. Significance and Use4.1 The key factors that determine image quality for highlycontrolled facial images (for ex
11、ample: passports, policemugshots, drive motor vehicle, etc.) are well understood withrespect to their use in automated FR systems and are a criticalfactor which directly affects the searching accuracy of the FRsystem.1This guide is under the jurisdiction of ASTM Committee E30 on ForensicSciences and
12、 is the direct responsibility of Subcommittee E30.12 on Digital andMultimedia Evidence.Current edition approved Dec. 1, 2017. Published January 2018. DOI: 10.1520/E3115-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
13、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.Copyright ASTM International, 100 Barr Harbo
14、r Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendatio
15、ns issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.2 Image quality also plays a major role in determining theextent to which a trained facial examiner is able to reach aconclusion as to whether two images containing faces arelikely to be of the same person or no
16、t. This applies to eitherreviewing a FR system candidate result set or 1:1 imagecomparisons.4.3 This guide provides guidance for the capture of facialimages under controlled, semi-controlled, and uncontrolledscenarios for constraints which can be categorized into thefollowing types of requirements:4
17、.3.1 Scene, refers to the content, subject and background inthe image,4.3.2 Photographic, refers to lighting, focus and otherconstraints required for image capture, and4.3.3 Digital, refers to the conversion of the captured imageinto a digital record.5. Scenarios5.1 Controlled Acquisition:5.1.1 This
18、 scenario is when all constraints can be controlledincluding equipment, the photographic environment (cameraposition, lighting, distance, background, and resolution), andthe pose and positioning of the subject. The subject can bedirected or positioned, the environment can be arranged toprovide ideal
19、 illumination, and suitable equipment is available.5.1.2 Referenced document ANSI/NIST-ITL-1-2011, Up-date 2015, Annex E, provides specifications on all aspects ofcontrolled acquisition scenarios.5.1.3 Annex A1 in this guide presents illustrative examplesfor controlled capture scenarios.5.1.4 Fig. 1
20、 provides an example of an optimal setting for acontrolled capture environment. The selection and placementof the lighting addresses the following variables:5.1.4.1 There is sufficient and uniform lighting to capture allvisible skin characteristics (that is, blemishes, moles, marks,etc.).5.1.4.2 To
21、avoid hot spots and shadows on the subjectsface.5.1.4.3 The 0.3 m to 0.6 m (1 ft to 2 ft) distance (with orwithout a backlight) between the background and the subject isintended to reduce background shadows.5.1.5 Fig. 2 provides examples of optimal facial imagescaptured. Frontal, right, left, and th
22、ree-quarter profile imagesshould be captured as these provide additional value forexaminers undertaking forensic comparison. The subjectshead is positioned in the image as shown.5.1.6 Automated image quality software is available fromvarious commercial suppliers that can help to determine if thefron
23、tal image is captured as per the recommendations.However, in all cases, a manual check is advised as thesoftware may not take into account all of the constraints.5.2 Semi-Controlled Acquisition:5.2.1 This scenario refers to when some, but not all,constraints can be controlled. Examples of this inclu
24、de pass-port photos not taken in a controlled environment, law enforce-ment mobile capture, crime scenes, access control, walk-through automated gates.5.2.2 In a semi-controlled environment, the following con-straints should be considered as a priority:5.2.2.1 Illumination,5.2.2.2 A single full fron
25、tal face with open eyes and neutralexpression.5.2.2.3 Elimination of convex lens distortion (subjectshould be more than1m(3ft)from the camera),5.2.2.4 Elimination of occlusions, andFIG. 1 Example of a Controlled Acquisition EnvironmentE3115 1725.2.2.5 Where available, multiple images should be cap-t
26、ured to compensate for shortcomings in individual images.5.3 Uncontrolled Acquisition:5.3.1 This scenario refers to when neither the environmentnor the subject can be controlled (for example, surveillance,hand held camera, body cameras, cell phones, etc.). It ischaracterized by high variations in qu
27、ality and content andtypically requires human review and specialized tools toidentify and extract usable facial content. (See NIST SpecialPublication 500-280v2.)5.3.2 In these situations, the person capturing the imageshould improvise to get the best image possible (see Fig. 3):5.3.2.1 When appropri
28、ate, use a camera flash or additionallights source(s) to improve illumination,5.3.2.2 Position the camera to get the best pose possible orprovide a visual attractor to influence the pose,5.3.2.3 A single full frontal face with open eyes,5.3.2.4 Elimination of convex lens distortion (subjectshould be
29、 more than1m(3ft)from the camera), and5.3.2.5 In these uncontrolled scenarios, multiple imagesshould be captured to compensate for shortcomings in indi-vidual images.6. Keywords6.1 capture equipment; facial image; facial recognitionFIG. 2 Example Poses from a Controlled Acquisition EnvironmentE3115
30、173NOTE 1Tennessee Bureau of Investigation, “Mug Shot Best Practices Guide,” available from https:/www.tn.gov/content/dam/tn/tbi/documents/MugShot Best Practices Poster.pdf.FIG. 3 Examples of Improper Poses from a Controlled Acquisition EnvironmentE3115 174ANNEX(Mandatory Information)A1. TABLESA1.1
31、See Tables A1.1-A1.3.TABLE A1.1 Description of a Controlled Acquisition EnvironmentNo. Item Description Comments1 Illumination Lighting shall uniformly illuminate the subject and thebackground.Use of an optional third light as a backlight (to eliminate shadowson the background) generally requires ab
32、out 1 m (3 ft) ofadditional floor space behind the subject. This additional spacemay not be available in all environments.Hot spots or reflections shall be minimized. Use of flash is discouraged. However, if a flash is used, wherepossible, either diffuse the light or bounce the light off aneutral-co
33、lored ceiling to avoid harsh, uneven lighting.Consideration should be made to the color of the ceiling toavoid casting unnatural color on the subject.2 Camera position The camera shall be at eye level and shall be mounted in ahorizontal position with no tilt.Possible solutions are to place subject i
34、n an adjustable seatedposition or to mount the camera on a pole and adjust itsheight.The camera height shall be positioned at the same height as thesubjects eyes and positioned approximately2m(6.5ft)fromthe subject.3 Background Background should be uniform light gray. 18 % grey is recommended as a b
35、ackground color. 18 %photographic grey cards and backgrounds are widely availablefrom photographic suppliers.The level of gray is less important than ensuring that it is aneutral gray and that the subjects head is clearlydistinguishable from the background with no shadows or otherobjects visible in
36、the frame.The background shall completely fill the image frame behind thesubject.TABLE A1.2 Optimal Subject AppearanceNo. Item Description Comments1 Facing Frontal:Subject shall face directly towards the camera with no morethan 5 variance from frontal in roll, pitch, and yaw.Visual cues that can ass
37、ist an operator in determining “forwardorientation” are:Profile:When there is a requirement for profile shots, the whole bodyshall be turned 45 and 90 right and left.(1) Both eyes are level on an imaginary horizontal line (zero rollangle),(2) Both ears are equally visible if unobstructed by hair) an
38、dnose is forward (zero yaw angle), and(3) The chin is neither elevated or dropped (zero pitch angle).2 Head coverings Head coverings, including hats and scarves, shall not be worn,unless for religious reasons or medical purposes.The full face shall be displayed and the ears should bedisplayed.3 Hair
39、 When capturing both frontal and profile images, the subjectshair should be moved back.The full face shall be displayed and the ears should bedisplayed.4 Glasses If the subject wears glasses, at least one frontal image shouldbe captured with glasses and one image without glasses.If the subject is we
40、aring glasses, glare from the lenses shall beavoided, for example, by adjusting the lighting.Eye patches are allowed only for medical reasons.5 Expression Subject shall have a neutral expression. It is the operator and subjects responsibility to ensure there areno smiles or grimaces.6 Mouth Mouth sh
41、all be closed.E3115 175TABLE A1.2 ContinuedNo. Item Description Comments7 Shoulder position Shoulder position shall be square and forward facing for frontalimages. Shoulder position shall be perpendicular for profileimages.8 Accessories Accessories should be removed.9 Make-up andcleanlinessThe subje
42、cts face shall be presented without heavy makeup ordirt.Use of a disposable wipe cloth is recommended to removeexcessive makeup or surface dirt.This may not be practical in noncriminal image capture.10 Face count Only one face per image is allowed. Take measures to ensure that other subjects are not
43、 captured,such as a baby in arms.11 Medical conditions If bruising, injuries, bandages, or medical conditions arepresent, these should be presented as is.The presence of injuries or bandages on the face will limit thevalue of the images for use with automated FR systems.Depending on the use case, it
44、 may be beneficial to capture anadditional image at a later date when the injuries are notvisible.TABLE A1.3 Optimum Parameters for Controlled AcquisitionNo. Item Description Comments1 Camera type Use a high-quality digital camera such as a digital single-lensreflex (DSLR) or a point and shoot camer
45、a with manualexposure override features.Digital cameras that lack manual exposure override are lesssuitable.The use of webcams and cell phone cameras is notrecommended.2 Camera resolution ANSI/NIST-ITL-1-2011, Update 2015, provides subject acquisi-tion profiles (SAP) that describe a set of character
46、istics ex-pected of the facial image with stringency of the requirementsincreasing with SAP level.Higher SAP levels result in larger pixel image sizes (height,width), on-disk file storage, and will require a correspondingincrease in the camera resolution.The highest level of SAP 50 and 51 are recomm
47、ended for foren-sic image analysis.3 ISO rating If the ISO setting on the camera is adjustable, it should be set tothe lowest value that also meets shutter and aperture require-ments (in accordance with Items 7 and 8 in this table).Operators should be familiar with the cameras automated fea-tures th
48、at may help simplify the adjustment of ISO, shutterspeed, and f-stop to compensate for low light conditions.The setting should be set so that there is no visible noise in theimage.4 Focus The operator can use auto or manual focus. Do not use fixed focus (for example, cell phones or disposablecameras
49、).Good results will normally be obtained by focusing on the eyearea.5 Face detectioncapability (facepriority auto fo-cus)Optional. If the camera has face detection capability, its use is recom-mended.If there are multiple subjects, it shall be verified that the correctface has been selected and is in focus.6 White balance The white balance setting on the camera should be adjustable tocapture natural colors.The white balance should be calibrated using 18 % gray back-ground or gray card. Calibration should be done as part of aregular preventive maintenance program
