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.