acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ...
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acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ...

acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ... acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ...

biometrics.nist.gov
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11.07.2015 Views

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSIONE.2 Digital requirementsE.2.1Pixel aspect ratioDigital cameras and scanners used to capture facial images shall use square pixels with a pixelaspect ratio of 1:1.E.2.2Image aspect ratioFor SAPs 30 and 32, the aspect ratio shall be 4:5 (480x600pixels). For SAP 40 and above, theaspect ratio shall be 3:4. SAP 40 specifies a minimum of 768x1024 pixels, which correspondsto this aspect ratio, allowing a COTS digital camera to be used for capture. Images from sometypes of camera with a different aspect ratio shall need to be cropped.E.2.3No interlacingInterlaced video frames shall not be used in the capture of a facial image.E.2.4No digital zoomDigital zoom (interpolation) to achieve specified resolution associated withSubject Acquisition Profiles shall not be used in the capture of a facial image.E.2.5Minimum number of pixelsThe minimum number of pixels in an electronic digital image shall be 480 pixels in thehorizontal direction by 600 pixels in the vertical direction. It should be noted that the imagequality of the captured mugshots and facial images may be improved as the number of pixels inboth directions are increased. However, as images are captured with an increased number ofpixels, the 4:5 (SAPs 30/32) and 3:4 (SAP 40 and above) (Width:Height) aspect ratio shall bemaintained.E.3 Photographic requirementsE.3.1Depth of fieldThe subject’s captured facial image shall always be in focus from the nose to the ears. Althoughthis may result in the background behind the subject being out of focus, this is not a problem. Itis recommended that auto-focus on the central part of face be used with digital cameraphotography. For optimum quality of the captured mugshot, the f- stop of the lens should be setat two f-stops below the maximum aperture opening when possible.E.3.2Subject lightingLighting shall be equally distributed on the face. There shall be no significant direction of thelight from the point of view of the photographer.For non-mobile SAPs (those other than 32, 42 and 52), the following conditions apply:May, 2013 DRAFT VERSION UPDATE 2013 Page 471

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSION• Subject illumination shall be accomplished using a minimum of three (3) pointbalancedillumination sources. Although a minimum of three photo lights isrequired for illuminating the subject’s face, two of these lights should besufficient for some operational environments. Use of a third light as a backlightgenerally requires about two feet of additional floor space behind the subject,which may not be available in all environments.• Appropriate diffusion techniques shall be employed and lights positioned tominimize shadows, and to eliminate hot spots on the facial image. These hotspots usually appear on reflective areas such as cheeks and foreheads.• Proper lighting shall contribute to the uniformity of illumination of thebackground described in the exposure requirement.• The region of the face, from the crown to the base of the chin, and from ear-toear,shall be clearly visible and free of shadows. In particular, there shall be nodark shadows in the eye-sockets due to the brow, and the iris and pupil of theeyes shall be clearly visible.E.3.3Background and lightingThis section does not apply to mobile SAPs (32, 42, or 52).The subject whose image is being captured shall be positioned in front of a background that is18% gray with a plain smooth flat surface 196 . A Kodak or other neutral gray card or densitometershall be used to verify this 18% gray reflectance requirement. The boundarybetween the headand the background should be clearly identifiable about the entire subject (very large volumehair excepted). There should be no shadows visible on the background behind the face image.Proper lighting shall contribute to the uniformity of illumination of the background.Ensure that the background completely fills the image frame behind the subject. If possible,avoid the presence of visible shadows and other objects in the background, such as a clock.E.3.4Exposure calibrationThis section does not apply to mobile SAPs (32, 42 or 52).The exposure shall be keyed to the background. Several areas of the recorded 18% graybackground shall be used to verify the proper exposure. The averages of the 8-bit Red, Green,and Blue (RGB) components within each area shall be calculated. Each of the RGB means shallfall between 105 and 125 with a standard deviation of ±10. Furthermore, for every area196An example of a paint formula that will approximate an 18% gray (on matte surface) is one quartOlympic Premium Interior Latex Eggshell, Base 3 - 72403, 101-1Y31.5, 109-8.5, or one quart BenjaminMoore & Co. Premium Interior Latex Flat Finish Wall Satin, Medium Base 215 2B, Formula: OY-8½ RX-3/4 BK-21 GY-4 WH-10, Area/Tint Code: B.472

ANSI/<strong>NIST</strong>-ITL 1-<strong>2011</strong> - UPDATE 2013 DRAFT VERSIONE.2 Digital requirementsE.2.1Pixel aspect ratioDigital cameras and scanners used to capture facial images shall use square pixels with a pixelaspect ratio of 1:1.E.2.2<strong>Image</strong> aspect ratioFor SAPs 30 and 32, the aspect ratio shall be 4:5 (480x600pixels). For SAP 40 and above, theaspect ratio shall be 3:4. SAP 40 specifies a minimum of 768x1024 pixels, which correspondsto this aspect ratio, allowing a COTS digital camera to be used <strong>for</strong> capture. <strong>Image</strong>s from sometypes of camera with a different aspect ratio shall need to be cropped.E.2.3No interlacingInterlaced video frames shall not be used in the capture of a facial image.E.2.4No digital zoomDigital zoom (interpolation) to achieve specified resolution associated withSubject Acquisition Profiles shall not be used in the capture of a facial image.E.2.5Minimum number of pixelsThe minimum number of pixels in an electronic digital image shall be 480 pixels in thehorizontal direction by 600 pixels in the vertical direction. It should be noted that the imagequality of the captured mugshots and facial images may be improved as the number of pixels inboth directions are increased. However, as images are captured with an increased number ofpixels, the 4:5 (SAPs 30/32) and 3:4 (SAP 40 and above) (Width:Height) aspect ratio shall bemaintained.E.3 Photographic requirementsE.3.1Depth of fieldThe subject’s captured facial image shall always be in focus from the nose to the ears. Althoughthis may result in the background behind the subject being out of focus, this is not a problem. Itis recommended that auto-focus on the central part of face be used with digital cameraphotography. For optimum quality of the captured mugshot, the f- stop of the lens should be setat two f-stops below the maximum aperture opening when possible.E.3.2Subject lightingLighting shall be equally distributed on the face. There shall be no significant direction of thelight from the point of view of the photographer.For non-mobile SAPs (those other than 32, 42 and 52), the following conditions apply:May, 2013 DRAFT VERSION UPDATE 2013 Page 471

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