Abstract: In a method for operating a fingerprint sensor including a plurality of ultrasonic transducers and a presence sensor, the presence sensor proximate the fingerprint sensor is activated, where the presence sensor is for detecting interaction between an object and the fingerprint sensor. Subsequent to detecting interaction between an object and the fingerprint sensor at the presence sensor, a subset of ultrasonic transducers of the fingerprint sensor is activated, the subset of ultrasonic transducers for determining whether the object is a human finger, where the subset of ultrasonic transducers is proximate the presence sensor such that the subset of ultrasonic transducers and the presence sensor can concurrently interact with the object.

Abstract: In a method for operating a fingerprint sensor including a plurality of ultrasonic transducers and a presence sensor, the presence sensor proximate the fingerprint sensor is activated, where the presence sensor is for detecting interaction between an object and the fingerprint sensor. Subsequent to detecting interaction between an object and the fingerprint sensor at the presence sensor, a subset of ultrasonic transducers of the fingerprint sensor is activated, the subset of ultrasonic transducers for determining whether the object is a human finger, where the subset of ultrasonic transducers is proximate the presence sensor such that the subset of ultrasonic transducers and the presence sensor can concurrently interact with the object.

Abstract: In a method for darkfield tracking at a fingerprint sensor, it is determined whether an object is interacting with the fingerprint sensor using a presence sensor. Provided an object is not interacting with the fingerprint sensor, a determination that a darkfield candidate image can be captured at the fingerprint sensor is made, wherein the darkfield candidate image is an image absent an object interacting with the fingerprint sensor. It is determined whether to capture a darkfield candidate image at the fingerprint sensor based at least in part on the determination that a darkfield candidate image can be captured at the fingerprint sensor. Responsive to making a determination to capture the darkfield candidate image, the darkfield candidate image is captured at the fingerprint sensor.