A display device includes field emission cathode apparatus for emitting electrons. A plurality of electron beams are formed from the field emission cathode apparatus. A screen, which has a phosphor coating facing the cathode receives the plurality of electron beams. The phosphor coating includes a plurality of pixels each corresponding to a different one of said plurality of electron beams. A grid electrode is disposed between the cathode and the screen for controlling the flow of electrons from the cathode. The field emission cathode includes extractor grid means, having a plurality of separately addressable portions associated with each of said plurality of pixels. A gamma transfer function between input data value and beam current is provided in order to emulate a conventional CRT. This can be achieved by use of a lookup table.