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

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSION(10 ppmm) detail on a subject’s face. The only difference between level-50 and level-51is that level-50 specifies the “head and shoulders” composition requirements while level-51 specifies the “head only” composition requirements.For a level-50 image capture profile, the minimum number of pixels in the digital imageshall be 3300 pixels in the horizontal direction by 4400 pixels in the vertical direction. 31Off-the-shelf 15 (or more) megapixel digital cameras satisfy this requirement. As analternative, allocating 70% of the image width for the head requires approximately 2400pixels for the “head only” facial capture. For a level-51 image capture profile, theminimum number of pixels in the digital image shall be 2400 pixels in the horizontaldirection by 3200 pixels in the vertical direction. Off-the-shelf 8 megapixel digitalcameras satisfy this requirement.The levels-50 and 51 SAPs allow for the encoding of face images that are consistent withthe discussion above and with the “face image capture requirements”. It should be notedthat the resolution aspect of the captured facial images might be improved as the numberof pixels in both directions are increased. Figure 5 illustrates the improvement in imagequality from levels 30 to 50/51. As images are captured with an increased number ofpixels, the 3:4 (Width : Height) aspect ratio shall be maintained.7.7.5.1.10 Level 52 (Mobile device best practice mugshots)The requirements for level 52 are based upon those of level 50, but are not fully inclusiveof all of those requirements. For instance, relative centering error and 18% grayscale withappropriate lighting may not be realistic for a mobile application. Specific roll, pitch andyaw requirements are not included in Level 52. See Table 11 for the completerequirements for SAP level 52.Figure 5: Examples of resolution for face SAP levels 30/32, 40/42, & 50/51/5231Identification applications require approximately 1700 pixels wide by 2515 pixels high on the face for the99th percentile male in the U.S. population. Allocating 50% of the image width for the head requiresapproximately 3400 pixels for a “head and shoulders photo” image width.May, 2013 DRAFT VERSION UPDATE 2013 Page 75