Abstract: Disclosed is an ultra-thin optical imaging sensor with anamorphic optics comprising of an image capturing panel an anamorphic optical lens of at least two optical magnification powers, and an imaging sensor. The image sensor captures a light reflection from an image deposited on the image capturing panel, which is optically compensated by the anamorphic optical lens. In the preferred embodiment, a folding mirror and a bending mirror is also provided to provide compactness to fold an incoming image towards the anamorphic lens, and the bending mirror then bends the compensated image received from the anamorphic lens to direct that image to an image sensor.

Abstract: A ranking-based automatic dark compensation circuit for efficiently estimating dark level in a CCD or CMOS image sensor. The ranking circuit comprises of k staggered comparators, each comparator having an associated temporary result register. Each comparator having two inputs, with the first input coupled to an output of the previous stage comparator and the second input coupled to its associated temporary result register. The temporary results are initialized to the largest possible dark value. At each stage, a comparison is made of a new input sample to a stored value of the temporary register. If the new sample is greater than the value of the associated temporary register, the value in temporary register is not changed and the new sample is passed to the next comparator. Conversely, if the new sample is smaller, then that new sample is stored into the temporary register, while the original temporary result is passed to the next comparator.

Abstract: A fingerprint recognition method includes iterative gamma correction that compensates moisture effect, feature extraction operations, directional morphological filtering that effectively links broken ridges and breaks smeared ridges, adaptive image alignment by local minutia matching, global matching by relaxed rigid transform, and statistical matching with Gaussian weighting functions.

Abstract: For use in capturing a fingerprint image, an optical fingerprint sensor. In one embodiment of the present invention, the optical fingerprint sensor includes: (1) a light source on a PCB assembly, (2) a diffuser that receives light from the light source, (3) a right angle prism that receives light from the diffuser, (4) a collimating lens that receives light from the prism, (5) a first mirror that receives light from the collimating lens, (6) a second mirror that receives light from the first mirror, (7) a third mirror that receives light from the second mirror, (8) an imaging lens that receives light from the third mirror, and (9) an image sensor on the same PCB assembly as the light source that receives light from the imaging lens.

Abstract: An on-chip FPN calibration method and circuits scheme applying a reference voltage signal to an array of calibration pixels coupled to a sensor matrix. Two data values are read from each bit line and used to calculate an offset and a gain error for a pixel column. A reference offset and a reference gain error value are then generated by computing the average offset and the average gain error from the collected offset and gain error values of each bit line. Calibration data for each bit line then comprises an offset difference and a gain error difference, the offset difference comprising the difference between the offset value for that bit line and the reference offset, and the gain error difference comprising the gain error difference between the gain error for that bit line and the reference gain error. The calibration data for each bit line is then stored in on-chip volatile memory and is used later under normal operation to compensate for the FPN effect.