Abstract:
A sensor receives a print image from an authorized person to form a template (21), and a candidate to form test data (11). Power spectral density (PSD) data for a template (21) and a candidate (11) are compared, to read out rotation and dilation; these are used to adjust the template or candidate preparatory to a correlation to find translation (51). After applying the translation, and refinement of the rotation and dilation, normalized spatial correlation values (NSCSVs) are used to measure the quality of the match (36) and thresholded (41) to make an early rejection (42) or acceptance (43) decision in very clear cases. Where the question is closure, isomorphic adjustment is applied to the entire template or candidate for a fairer comparison in their overlap area.