VISUAL WEIGHT

Prof. Arq. Raúl Parada Castellano

The visual weight of an image is defined as the visual force that emerges due to the contrast of light between the different elements that compose it.

The point where the visual weight of an image places is named the Center of Gravity (CG). When the CG coincides with the Geometric Center (CC) of the image, we establish that the image is balanced.

L * = Average lightness of the image (0 = total black /1=total white) PVi = Visual Weight of the integral image (between 0 and 0.5 at integral figures)

HISTORICAL BACKGROUND

. Harvard University:

- Denman. W. Ross (1853-1935) ¨A Theory of Pure Design¨

- Rudolf Arnheim (1904-2007) ¨Art and Visual Perception: A Psychology of the Creative Eye¨

. Staatliches Bauhaus:

- Josef Albers (1888-1976) ¨Interaction of Color¨

- Johannes Itten (1888-1967) ¨The Elements of Color¨

At present: Raúl Parada Castellano (2015) ¨Study of balance of images using visual weight¨

PARTIAL WEIGHT AND INTEGRAL WEIGHT

The visual weight is established as ¨partial¨ when we select a figure and segregate it of the rest of the image (bottom). Here, the weight depends on the contrast power that the figure creates respect of its bottom.

Partial weight of a duck figure

Integral weight of a set of figures

The visual weight is established as ¨integral¨ when the totality of the image is interpreted as a figure. In this case, the visual weight of the image depends on the contrast power on every visual element respect of the average lightness of the image.

The visual weight does not need of any perceptual recognition in order that it appears. Only it needs of a lightness interaction in the image, therefore, is formed as a direct and omnipresent visual force.

THE PSYCHOLOGICAL WEIGHT AND THE CONTRAST OF LIGHTNESS

The psychological weight is the sensation that everything what we see is submitted by force of the gravity, since our vision is totally accustomed and linked to the vital conditions that limit us in our environment. Therefore, any visual perceived element (though this one is abstract) associates automatically a vertical force with down direction.

Minor light contrast a figure creates respect of his bottom, minor sensation of psychological weight we perceive. This owes that the loss of contrast of lightness in a figure provokes a loss in our capacity of visual recognition, and in turn an increase in the visual sensation of levity, since this one is faded away into the bottom as is losing its contrast.

Depending on the scene in which a figure is inserted, this one will be able to have a different visual weight, which implies that the visual weight is variable depending on the different factors of appearance that concern the scene.

PERCEPTUAL WEIGHT AND VISUAL WEIGHT

The perceptual weight is the weight that is assigned to a visual object, after recognizing it and to process it, that is to say, it is the weight that we think mentally that it can have an object independently of the scene in which it is placed. Whereas the visual (psychological) weight is a direct sensation that appears automatically in our visual (genetic) processes, that is to say, it appears without the conscious processing (subjective) of the image. Thus, it depends on the light interactions that appear in the entire configuration of the image.

Black feather on clear bottom:Example of contrast between a high visual

weight and a low perceptual weight

The perceptual weight is always the same one, whereas we do not have a new experience relative to the object that modifies it. On the other hand, the visual weight is variable, that is to say, it changes as the factors of variability of appearance of the scene change theirs values.

DETERMINATION OF THE VISUAL WEIGHTThe calculation of the visual weight is realized establishing the following psycophysical relation:

Physical Action (Light - Space) Sensory Action (Visual Sensation)

A) Sensory action due to the light: 1º- Light = Spectrum of reemission of every visual element Quantity of light 2º- Spectral sensibility of the human vision to the light Luminance3º- Perceptual human response to changes of light Lightness (L*)B) Sensory action due to the space: Space = Two-dimensional Surface Surface in which the light reaches Surface of the human frame (Sup)

Relation (light - space) P = (L*/100) · Sup

Lightness Interaction Lr = │(Lf/100) – (L*/100)│ Relative Weight Pr = Lr· Sup

Quantity of light

Luminance

Lightness

- The surface of the visual human frame can be represented by the figure of a rectangle to simplify its calculation. The total surface of the image is equal to 1, therefore, every single element that composes it will have a surface between 0 and 1. - The luminosity divides between 100 to obtain values between 0 and 1.

DETERMINATION OF THE GRAVITY CENTER IN AN IMAGE

Axes of reference of the image (X, Y). The horizontal axis ¨X ¨ and the vertical axis ¨Y ¨ establish as axes of coordinates of an image on the analogy of our axes of visual reference.

Geometric Center of the image (CC)

Gravity Center in an image (CG)

The geometric center of the image is established as the point that defines the center of the image. Therefore, it uses as reference to determine the degree of balance of the image.

The gravity center is defined by the coordinates (XCM, YCM) on the axes of reference where there places the resultant force of the visual weight of the image.

mv1, mv2, …, mvn are visual masses, y xv1,xv2….xvn e yv1,yv2,..., yvn are coordinates of the centers of the different visual masses to the axes of reference ¨X ¨ and ¨Y ¨ of the frame of the visual image.

USEFULNESS OF THE VISUAL WEIGHT

The visual weight and the calculation of the C.G acquire the quality of important analytic tools in the creation of any visual composition. In different artistic disciplines as for example; art, painting, photography, cinema, graphical design, advertising, architecture, engineering and design in general, the visual weight and the calculation of its balance are established as systems of great value in the development of the creative composition.

eje

EXAMPLE OF PRACTICAL APPLICATION

How PV works:Youtube; https://www.youtube.com/watch?v=X7yh67O4CqQ