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

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSIONthe IAP level is specified in the Type-17 record.Table 13 Subject acquisition profiles for irisCAPTURE IAP 20 IAP 30 IAP 40Iris diameter in true, non-upscaled pixels > 140 pixels > 170 pixels > 210 pixelsNumber of (quasi-) simultaneously captured eyes > 1 > 1 2Exposure time < 33 ms < 15 ms < 10 ms7.7.6 ResolutionMany of the record types in this standard include images as the data field. Each imageformatted in accordance with this standard shall appear to have been captured in anupright position and approximately centered horizontally in the field of view. Thescanning sequence (and recorded data) shall appear to have been from left-to-right,progressing from top-to-bottom. For the purpose of describing the position of each pixelwithin an image to be exchanged, a pair of reference axes shall be used. The origin of theaxes, pixel location (0,0), shall be located at the upper left-hand corner of each image.The x-coordinate (horizontal) position shall increase positively from the origin to theright side of the image. The y-coordinate (vertical) position shall increase positively fromthe origin to the bottom of the image.Many of the record types in this standard use the term “resolution”, in the record typename, field names or in the text describing characteristics about the fields. Generally, theusage shares the commonality of describing pixels per unit of measure. In many cases, aqualifier is used before the term, such as “scanning” resolution or “transmitting”resolution.All record types containing images are variable resolution except for Type-4, which has afixed resolution. Record Type-4 shall not be used for anything but the 500 ppi class. Thescanner resolution is specified for Record Types 10, 13, 14, 15, 16, 17, 19 and 20 usingScanned horizontal pixel scale / SHPS (See Section 7.7.8.7) and Scanned verticalpixel scale / SVPS (See Section 7.7.8.8.) These Record Types can handle all resolutions,500 ppi and above, and are thus variable-resolution image records.Record Type-7 does not include a field to specify resolution. In previous versions, Field1.011 Native scanning resolution / NSR and Field 1.012 Nominal resolution / NTRapplied to Record Type-4 and Record Type-7: User-defined image record. In thisversion, NSR and NTR only apply to Record Type-4: Grayscale fingerprint image,unless specifically stated otherwise in a domain's specifications. This allows users to usedifferent resolutions for the Type-7 record. Since Type-7 records are user-defined, thesender and receiver must exchange information concerning the resolution of the data. Inmany cases, it is contained in the data record headers.As used within this standard, and consistent with the definitions in Section 4, thefollowing categorization of terms related to resolution is provided to assist the reader inclearly understanding and interpreting these terms:78