1. A computing device comprising: a liquid crystal display (LCD) device, having an array of pixels, provided to display a video or an image from the computing device, the LCD device further comprising: an LCD unit including an array of liquid crystals, each of the pixels in the LCD device corresponding to one or more of the liquid crystals; an array of photosensors disposed behind the array of liquid crystals, each of the photosensors corresponding to one or more of the liquid crystals that are configured to open substantially to allow a reflected light to pass through onto some or all of the photosensors, wherein the reflected light is from a scanning object being placed against the LCD device; and a circuit module, coupled to the photosensors, reading out sensing signals from the photosensors to produce an image of the scanning object.