An electronic device may have a display with an array of pixels. The device may have an array of components such as an array of light sensors for capturing fingerprints of a user through an array of corresponding transparent windows in the display. A capacitive touch sensor, proximity sensor, force sensor, or other sensor may be used by control circuitry in the device to monitor for the presence of a user's finger over the array of light sensors. In response, the control circuitry can direct the display to illuminate a subset of the pixels, thereby illuminating the user's finger and causing reflected light from the finger to illuminate the array of light sensors for a fingerprint capture operation. The display may have display driver circuitry that facilitates the momentary illumination of the subset of pixels with uniform flash data while image data is displayed in other portions of the display.