A series of autostereograms of a three dimensional scene is displayed. The apparent depth of a reference surface in the scene is varied from one autostereogram of the series to another. A human viewer looks at the autostereograms, adjusting the eyes to viewing of a surface at an arbitrary depth. When the apparent depth of the surface corresponds to the arbitrary depth, the human viewer will perceive a three dimensional effect and signal this with a feedback signal. Upon detection of the feedback signal a further autostereogram is displayed instead of the series of autostereograms. The further autostereogram displays of a further three dimensional scene containing a further reference surface, in which a further apparent depth of the further reference surface is selected according to the apparent depth for which the viewer feedback was received. Thus the further apparent depth is adjusted to the setting of the eyes of the human viewer. In an embodiment, the position of the eyes of the human viewer is monitored and the further autostereogram is adapted as the viewer moves his or her eyes to keep the depth perception constant. In another embodiment the depth perception is enhanced by supplying a stereophonic sound simulating a sound source related to the scene.
Displaying autostereograms of various depths until proper 3D perception is achieved