Image noise is random (not present in the object imaged) variation of brightness or color information in
images, and is usually an aspect of
electronic noise. It can be produced by the
sensor and circuitry of a
scanner or
digital camera. Image noise can also originate in
film grain and in the unavoidable
shot noise of an ideal photon detector. Image noise is an undesirable by-product of image capture that adds spurious and extraneous information.