Abstract: An electronic device may have a camera module. The camera module may include a camera sensor and associated image preprocessing circuitry. The image preprocessing circuitry may analyze images from the camera module to perform motion detection, facial recognition, and other operations. The image preprocessing circuitry may generate signals that indicate the presence of a user and that indicate the identity of the user. The electronic device may receive the signals from the camera module and may use the signals in implementing power saving functions. The electronic device may enter a power conserving mode when the signals do not indicate the presence of a user, but may keep the camera module powered in the power conserving mode. When the camera module detects that a user is present, the signals from the camera module may activate the electronic device and direct the electronic device to enter an active operating mode.

Abstract: An imager having special light shielded, optically black pixels in each row of the imager's pixel array. Ideally, the optically black pixels should only output black pixel and reset signals. Since the optically black pixels of each row experience the same row-wise noise as the active pixels in the associated row, the optically black signals are used as reference signals to cancel out the row-wise noise, from reset and pixel signals, seen in a particular row.