A system for determining a distance to an object comprises an image capture device (101) which has a coded aperture and an image sensor which is positioned out of a focus plane of the coded aperture. A receiver (103) receives an image of a scene from the image sensor and a detector (105) detects at least two image objects of the image corresponding to ghost images of the object resulting from different openings of the coded aperture in response to an optical characteristic of the object. A distance estimator (107) then determines a distance to the object in response to a displacement in the image of the at least two image objects. The distance may be to a person and the image may be a bright pupil image wherein pupils are enhanced by reflection of light by the retina. The image may be compensated by a dark pupil image of the scene.