This document details the results of tests carried out on the Primagraphics Greyscale 500 DPI Scanner , with reference to its use for scanning fingerprint forms. The results indicate that the scanner will meet the requirements, although the full range of tests must be carried out to guarantee full compliance. For small distances, the separation between adjacent bars is calculated from the Ronchi test image.
Complex software is used to determine bar position on the image with sub-pixel accuracy.
Figure 1 shows a maximum error horizontally of 0.1 pixel, and a DPI of 501.069. Figure 3 shows the greyscale linearity of the scanner, taken from a horizontal scan. This shows the highly linear response being achieved. A value of 1 is ideal, while a value of 0 implies no response. Figures 4 and 5 show that the scanner easily meets the minimum requirement.