Segregation of some mesh-derived textures evaluated by free viewing

Beginning with a hexagonal mesh, a family of equiluminous geometric textures can be formed by rotating each line segment by a fixed amount. Such textures vary both in line orientation and in the sizes of the intervening spaces or "holes". In the Fourier domain the textures have the same discrete two-dimensional frequency components but the amplitudes vary. The segregation of texture pairs as figures in grounds has been assessed for free viewing by the ratings of 10 subjects. Line segment orientation information alone cannot explain the results. Linear regression techniques were used to examine the correlation between the subjects' ratings and physical differences between figures and grounds. Significant correlations were found with (a) the amplitudes of the low-frequency Fourier harmonics of the textures and (b) maximum hole size, but not with the third harmonics or line segment orientation. Patterns composed of mirror-image pairs are very poorly discriminated; in these cases line orientation information may be used.