THE IMPORTANCE OF MASS IN LINE DRAWINGS OF FACES

Previous research (Davies, Ellis and Shepherd, 1978; Rhodes, Brennan and Carey, 1987) has shown that accurate line drawings of familiar faces are identified rather poorly. However, artists can produce lifelike portraits with pen and ink, and Pearson and Robinson (1985) described an automatic method for producing computer-drawn sketches ('cartoons') of faces which appear very similar to those produced by a human artist. In this paper we show that subjects can identify famous faces depicted in such computer-drawn 'cartoons' almost as well as full grey-scale images. The cartoon algorithm comprises two components. One component draws lines at the locations of intensity changes corresponding to luminance valleys and edges (the 'valledge' detector). The other component applies a 'threshold' to the original intensity distribution, and replaces any area darker than threshold with black. Thus the full cartoon contains both 'line' and 'mass'. Neither the valledges nor the threshold components alone were as well identified as full cartoons containing both components. The results suggest that the addition of the threshold component adds significantly to the identifiability of line drawings of faces.