Method of classifying fingerprints
First Claim
1. The method of classifying fingerprints comprising the steps of:
- making an impression of a fingerprint on a two-dimensional surface, transforming the two-dimensional surface representation of the fingerprint impression into a representation of a three-dimensional surface with a predetermined set of first and second coordinates and with a variable third coordinate for each set of first and second coordinates, the third coordinate having a value dependent upon the frequency of occurrence or ridge lines at a specific set of first and second coordinates when the origin of the first and second coordinates is taken at multiple positions over a prescribed part of the fingerprint impression, determining the values of local spatial derivatives of a plurality of different areas of the three-dimensional surface, and concatenating said values in a predetermined order to construct a descriptor code for the fingerprint.
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Abstract
A method for identifying fingerprints is disclosed; the method produces a descriptor code which is uniquely related to a given fingerprint impression. A fingerprint pattern is transformed into an informational model which represents the relative location of all data points with respect to selected groups of other data points. The method comprises the steps of transforming the fingerprint impression into a representation of a three-dimensional surface wherein the Z-axis coordinate has a value dependent upon the frequency of occurrence of ridge lines at a specific set of X-axis and Y-axis coordinates when the origin is taken at multiple positions over a prescribed part of the fingerprint impression, determining the values of local spatial derivatives, such as the surface curvature of a plurality of different areas of the three-dimensional surface, and concatenating the values in a predetermined order to construct a descriptor code for the fingerprint.
72 Citations
17 Claims
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1. The method of classifying fingerprints comprising the steps of:
- making an impression of a fingerprint on a two-dimensional surface, transforming the two-dimensional surface representation of the fingerprint impression into a representation of a three-dimensional surface with a predetermined set of first and second coordinates and with a variable third coordinate for each set of first and second coordinates, the third coordinate having a value dependent upon the frequency of occurrence or ridge lines at a specific set of first and second coordinates when the origin of the first and second coordinates is taken at multiple positions over a prescribed part of the fingerprint impression, determining the values of local spatial derivatives of a plurality of different areas of the three-dimensional surface, and concatenating said values in a predetermined order to construct a descriptor code for the fingerprint.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
Specification