disclosed is an identity card having grid images thereon comprised of a linear grid structure . in various embodiments , the grid depths of the individual grid images differ and can produce several different image colors . the card in a further embodiment can comprise a number of layers which are laminated together around a card core which has a window located therein . a number of variations of grid images can be included and / or superposed in the window in order to provide a security identification system which is extremely difficult to forge . also disclosed are numerous combinations of grid structures some of which include grid images which may be absorption images and / or phase images .