Calibration and correction in a fingerprint scanner
AssigneeCross Match Technologies, Inc.
InventorsRichard D. Irving, Walter Guy Scott
Life of this patent
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Abstract
A calibration and correction procedure for a fingerprint scanner. The calibration and correction procedure performs an automatic calibration procedure and gray level linearity procedure. The automatic calibration procedure includes a brightness function to correct for distortions in brightness, a focus check function to identify when the fingerprint scanner is out of focus, and a geometric distortion function to correct for imperfect linearity in the geometry of the fingerprint scanner. The gray level linearity procedure corrects for linear distortions in brightness and contrast of gray levels.
Claims21
A method for calibration and correction of a fingerprint scanner system, comprising the steps of:
- (1) scanning a calibration target having brightness test information, focus test information, and geometric distortion test information using the fingerprint scanner system:
- (2) performing an auto-calibration procedure of the fingerprint scanner system using information from the scanned calibration target;
- and
- (3) performing a gray level linearity procedure for providing a linear brightness and contrast response when taking fingerprints.
A method for calibration and correction of a fingerprint scanner system, comprising the steps of:
- (1) scanning a calibration target having brightness test information, focus test information, and geometric distortion test information using the fingerprint scanner system;
- (2) performing an auto-calibration procedure of the fingerprint scanner system, wherein said auto-calibration procedure comprises the steps of:
- (a) performing a brightness function to correct for distortions in brightness;
- (b) performing a focus check function to identify when the fingerprint scanner system is out of focus;
- and
- (c) performing a geometric distortion function to correct for imperfect linearity in the geometry of the fingerprint scanner system;
- and
- (3) performing a gray level linearity procedure for providing a linear brightness and contrast response when taking fingerprints.
A method for calibration and correction of a fingerprint scanner system, comprising the steps of:
- (1) scanning a calibration target having brightness test information, focus test information, and geometric distortion test information using the fingerprint scanner system;
- and
- (2) performing an auto-calibration procedure of the fingerprint scanner system, wherein said auto-calibration procedure comprises at least one of the steps of:
- (a) performing a brightness function to correct for distortions in brightness;
- (b) performing a focus check function to identify when the fingerprint scanner system is out of focus;
- and
- (c) performing a geometric distortion function to correct for imperfect linearity in the geometry of the fingerprint scanner system.
Dependencies are inferred from the claim text.