Pictorial balance is a bottom-up aesthetic property mediated by eye movements. A theoretical model of a primitive visual operating system could explain balance.

Abstract

Abstract This paper identifies a specific pattern of luminance in pictures that creates a low level neuro-aesthetic effect and provides a theoretical explanation for how it occurs. Given that pictorial balance is associated with a unified, harmonious picture and that there is a pictorial effect known to painters and historically documented that does just that, it was thought that such pictures are perfectly balanced. Computer models of these pictures were found to have bilateral quadrant luminance symmetry with a lower half lighter by a factor of ~ 1.07 +/- ~0.03. Two different methods are proposed to calculate balance. A study was done comparing the identical picture in two different frames with respect to whether they appeared different given that the sole difference is balance. Results show that with the observers, mostly painters, there was a significant correlation between average pair imbalance and the appearance of difference indicating at a minimum that these methods can be used for calculating pictorial balance. For those who can disregard saliency the effect is the result of the absence of forces on eye movements created by imbalance. The unaccustomed force invoked by imbalance causes fatigue when viewing pictures carefully. The second method enables calculations of balance in non-rectangular pictures, explains why balance affects eye movements and can be a primitive visual operating system.