Abstract
The concept of pictorial balance as a visual center-of-mass effect originated at the beginning of the 20th century to explain why some paintings evoke feelings of unity and harmony. It had never been mentioned in art commentary of the previous 500 years and is an unsubstantiated but widely assumed illusion. However, the visual basis for this illusion exists, and it is the object of this paper to show what balance is, how it is calculated and what it says about the visual system by means of the study of an unnamed pictorial effect. This is known by painters to give a picture a feeling of being remarkably unified and harmonious and enables the eye to move smoothly and easily around the picture so that every part has equal importance. This was first described by a 17th century critic Roger de Piles and subsequently by a few renowned artists. The author thought that this was due to the painting being in a state of perfect balance. Computer modeling found that such a picture must have bilateral luminance symmetry with a lighter lower half by ∼1.07 and that a picture with a white frame on a black ground is seen as one object. A study was done in which the identical picture in two slightly different frames could seem different to subjects who viewed them in sequence, the sole difference being the balance of the two images, some of which were perfectly balanced. It showed that subjects could see relative states of balance according to an algorithm and strongly suggested that the effect was seen.
The algorithm is derived from an idea as to how a primitive organismu could organize its visual experience to see other organisms. These are defined as collections of lights moving together against a ground. It divides the organism into two equally luminous parts which are further bisected. A virtual rectangle is drawn around the four parts to form a picture. Balance is calculated by a center of quadrant luminance equation analogous to a center-of-mass calculation. This defines the organism as an ever changing vector or rectangular halo and shows why a picture viewed from any angle is seen as if it were directly in front of the viewer.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
A revised statistical calculation and interpretation. Various small redactions throughout the paper. Various references of importance. Supplemental files have been revised