Systems and methods for detecting data acquisition conditions using color-based penalties can include a computing device obtaining a sequence of images acquired by a photodetector. The computing device can determine, for each pixel position of a plurality of pixel positions associated with the sequence of images, a respective penalty score indicative of a similarity between a color value of a pixel of the pixel position and a desired color value. The desired color value can represent a color property of light emitted from body parts of users when placed opposite to the photodetector. The computing device can determine, using penalty scores of the plurality of pixel positions, a relative position of a body part of a user with respect to a desired position.

Systems and methods for blood pressure estimation using smart offset calibration can include a computing device associating a calibration photoplethysmographic (PPG) signal generated from a first sequence of image frames obtained from a photodetector of the computing device with one or more measurement values generated by a blood pressure measurement device different from the computing device. The computing device can obtain a recording PPG signal generated from a second sequence of image frames obtained from the photodetector, and identify a calibration model from a plurality of blood pressure calibration models based on the calibration PPG signal and the recording PPG signal. The computing device can generate a calibrated blood pressure value using the recording PPG signal, features associated with the calibration PPG signal and the identified calibration model.

A dermatoglyph detector includes a detection circuit and an electronic processor unit. The detection circuit includes an electrically conductive thin film in which there are formed both electrodes that are arranged to come into contact with the skin of a portion of a human body and also conductive tracks connecting the electrodes to the processor unit. The processor unit is arranged to determine electrical characteristics of the body portion extending between each pair of electrodes in contact with the skin, and to execute a computer program for acting on the basis of the determined electrical characteristics to distinguish between an authentic body portion and a fake body portion. The detection circuit includes at least two track segments of different shapes between two calibration terminals so as to present an impedance ratio that is not equal to unity.

A deep finger ultrasonic sensor device includes an array of ultrasonic transducers and an array controller configured to control activation of ultrasonic transducers of the array of ultrasonic transducers during an imaging operation for capturing a depth image of a finger, where the depth image includes a plurality of features inside the finger. The array controller is configured to control transmission of ultrasonic signals and receipt of reflected ultrasonic signals during the imaging operation, where the reflected ultrasonic signals are utilized in generating the depth image of the finger.

The technology described in this document can be embodied in a method that includes obtaining, by one or more image acquisition devices, a first image of a portion of a human body under illumination by electromagnetic radiation in a first wavelength range, and obtaining a second image of the portion of the human body under illumination by electromagnetic radiation in a second wavelength range. The method also includes generating, by one or more processing devices, a third image or template that combines information from the first image with information from the second image. The method also includes determining that one or more metrics representing a similarity between the third image and a template satisfy a threshold condition, and responsive to determining that the one or more metrics satisfy a threshold condition, providing access to the secure system.

A method for driving a display device is performed by the display device. The method includes: displaying a first image including user convenience information through a display panel; generating sensing data corresponding to a fingerprint sensing area by using a photoelectric sensor; and determining whether a sensed fingerprint corresponding to the sensing data is a fake fingerprint by comparing expected sensing light illuminance information based on the first image with sensed light illuminance information of the sensing data. The first image includes a first color pattern in the fingerprint sensing area of the display panel. A fake-determination image pattern includes the first color pattern and a second color pattern different from the first color pattern.

The technology described in this document can be embodied in a method that includes obtaining, by one or more image acquisition devices, a first image of a portion of a human body under illumination by electromagnetic radiation in a first wavelength range, and obtaining a second image of the portion of the human body under illumination by electromagnetic radiation in a second wavelength range. The method also includes generating, by one or more processing devices, a third image or template that combines information from the first image with information from the second image. The method also includes determining that one or more metrics representing a similarity between the third image and a template satisfy a threshold condition, and responsive to determining that the one or more metrics satisfy a threshold condition, providing access to the secure system.

A display device includes a display panel and a fingerprint authentication device disposed under the display panel. The fingerprint authentication device includes a sensor device and an optical filter. The sensor device includes a first area and a second area in a plan view and sensing light passing through the display panel. The optical filter is disposed between the display panel and the sensor device, overlaps the first area and does not overlap the second area in the plan view, and blocks the light of a certain wavelength range.

A circuit, system, and method for measuring or detecting pressure or force of a fingerprint on an array of electrodes is described. Pressure or force may be measured or detected using a processed image of the fingerprint, or by measurement of capacitance of deformed variable capacitors.

The disclosure facilitates fingerprint recognition, user authentication, and prevention of loss of control of personal information and identity theft. The disclosure also facilitates identifying spoofed fingerprint authentication attempts, and/or securing user touch sensitive devices against spoofed fingerprint authentication attempts.