Optical fingerprint sensor with enhanced anti-counterfeiting features

A method of biometric sensing, comprising:

• acquiring an image of an object by a biometric sensing device, the biometric sensing device including a pixel array of a combination of sensing pixels and positioning pixels, wherein the positioning pixels are dark pixels;
• retrieving minutia points from the acquired image;
• calculating vectors of the minutia points with reference to the positioning pixels;
• calculating shifts by comparing the vectors to reference vectors generated from a reference image, wherein the positioning pixels are insensitive to information in either the acquired image or the reference image;
• and
• determining a match between the acquired image and the reference image by evaluating consistency of the shifts.

A method of fingerprint verification, comprising:

• capturing a fingerprint image by an image sensing device, the image sensing device including a pixel array of a combination of monochromatic pixels configured to capture a minutia map of the fingerprint image, color pixels configured to capture a skin tone of the fingerprint image, and positioning pixels configured to provide vectors of minutia points in the minutia map with reference to the positioning pixels;
• comparing the minutia map to a reference minutia map of a reference fingerprint image;
• comparing the skin tone to a reference skin tone of the reference fingerprint image;
• evaluating consistency of shifts between the vectors and reference vectors of the reference fingerprint image;
• and
• determining a match between the fingerprint image and the reference fingerprint image based on the comparing of the minutia map, the comparing of the skin tone, and the evaluating of the consistency.