Figure 6.

Extreme cases of images that serve to illustrate the space that best separates art images from non-art images (Figure 5). (A,B) show non-art images, while (C,D) show artworks. The image of the plant pattern in (A) is rich in structure (low P_a(22)) but is highly self-similar with little variability across the image (low P_f(12)). The large vista scene in (B) represents a highly homogeneous image that lacks structure like edges or different colors (high P_a(22)). The painting in (C) (A. R. Mengs, 1769) is atypical in that it contains large, relatively homogeneous regions (high P_f(12)), similar to objects. The painting in (D) (Monet, 1891) has a very rich structure (low P_a(22)) but it is not as self-similar (higher P_f(12)) as most images of plant patterns, vegetation or lichen growth patterns. See Table 2 for values of P_f(12) and P_a(22).