IMAGE BLUR AS A PICTORIAL DEPTH CUE

A range of cues are already known to mediate depth perception in pictu res and have been exploited by artists in drawings and paintings. Mode rn images are commonly generated by photographic or video equipment, a nd these images contain a depth cue that cannot be found in artistic d epictions of natural scenes: different image regions are often blurred by different amounts, because of depth of focus limitations. Demonstr ations presented here show that this selective image blur also acts as a pictorial depth cue, even when other pictorial cues are removed. Ex perimental data indicate that the degree of blur al borders between bl urred and sharp image regions is used by the visual system to establis h the depth ordering of different regions. Selective image blur is thu s a potentially useful addition to computer-generated and cartoon imag es to enhance the impression of depth they convey. It may well also co ntribute to depth perception in natural retinal images, because the de pth of focus of the human eye is limited.