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

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