1. Apparatus for producing a three-dimensional image comprising; a display means ( 1 ) capable of producing a three dimensional image ( 3 ) which is capable of being viewed from a range of viewing positions, a monitoring means ( 9 ) for determining the viewing position of at least one observer, and control means ( 8 ) responsive to the monitoring means ( 9 ) for controlling the display means ( 1 ), characterised in that the display means ( 1 ) comprises a plurality of addressable sub-regions controlled by the control means ( 8 ) such that priority is given to producing a complete image for the at least one determined viewing position.