A display apparatus comprises a spatial light modulator and optical
elements in series therewith. The optical elements provide a first
parallax element being a parallax barrier capable of directing light
output from the display apparatus into a first plurality of viewing
windows, and a second parallax element capable of directing light output
from the display apparatus into a second plurality of viewing windows. In
a first mode, the first and second parallax elements have substantially
no directional effect on the light output from the display apparatus. In
a second mode, the first parallax element directs light output from the
display apparatus into the first plurality of viewing windows and the
second optical element has substantially no directional effect. In a
third mode, the second optical element directs light output from the
display apparatus into the second plurality of viewing windows and the
first parallax element has substantially no directional effect.