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

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSIONFor each sampling point in the Region of Interest, distances between ridge peaks, measuredperpendicular to ridge flow, shall be reported in 2-character decimal format using units of 10micrometers (0.01mm). The size of the area around the sampling point (window size) usedto determine measurements is left to the discretion of the implementer, and may vary withinan image. Unknown values shall be set to “XX”. Valid values are therefore “01” (0.01mm)through “99” (0.99mm or greater). (In practice, the actual stored values are likely to be “30”to “70” in most cases (0.3 – 0.7 mm). The 2-character decimal wavelength values for eachsampling point are concatenated left to right for all sampling points in a row. Each subfieldcorresponds to one row of the map, in order from top to bottom. The number of characters inone subfield is twice the number of sampling points in one row.8.9.7.11 Field 9.313: EFS ridge wavelength map format / RWFThis field permits setting the sampling frequency or data representation format used inField 9.312: EFS ridge wavelength map / RWM to values other than the defaults, andis conditional on the presence of Field 9.312. It consists of two information items:• The first information item (sampling frequency / FWS) is set by default to0.41mm (0.016”). This information item may be used to define higherresolution sampling frequencies than the default: valid settings range from“1” (0.01mm) through “41” (0.41mm).• The second information item (data format / FDF) is optional. It defines theformat used in Field 9.312. The default (and currently the only setting) is theuncompressed (“UNC”) format.8.9.7.12 Field 9.314: EFS tonal reversal / TRVRidges in friction ridge images are generally represented as dark areas, with valleys as lightareas. This field indicates whether the entire image is reversed tonally (black-for-white). Ifall or part of the image is reversed tonally, this 1-character optional field is set to theappropriate value from Table 36. Otherwise this field is omitted.Partial tonal inversion can occur in different ways. If definable portions of the image arenegative, Field 9.357: EFS local quality issues / LQI can be used to define the specifictonally reversed areas. 85 Note that in some cases, the tonal reversal is so mixed that onlyportions of individual ridges are reversed, making it impractical or impossible to define thetonally reversed areas. 86When this field is set, the image in the Type-13 record shall be left as it was originallyreceived (i.e., tonally reversed): setting this field and reversing the image when saving willresult in inconsistent data. When this field is set, a software user interface may display thetonally corrected image, but save the image as originally received with this field set.85Example: very heavy pressure can leave matrix from valleys, whereas lighter pressure at the edges of thesame impression would leave matrix from ridges.86Example: if light powder is applied from a single direction, one edge of each ridge is light and theremainder dark.May, 2013 DRAFT VERSION UPDATE 2013 Page 153