The Representation of the Visual World in Photography

As a visual sign, a photographic image usually represents an object or a scene; this is the habitual way of seeing it. But it accomplishes that common semiotic task by representing various formal features of the object or scene: its color, shape, texture and spatial distribution of light. The curious fact is that photography does this in very different ways. With respect to color, a pigmented object produces a certain spectral distribution of light, and an ordinary photograph of that object causes approximately the same spectral distribution. The pigmented emulsions of the photographic paper act upon light in the same way as the pigmentation of the objects. In this sense, photography represents color by sharing physical properties with the objects. In truth, instead of representing color, it reproduces color. We have an indexical aspect of photography here (an index being a sign that is physically connected to the object that it represents). This is quite different from what occurs with the representation of the spatial distributions of light (transparency, translucency, mirror-like appearance, gloss, matt quality, etc.) by photography. A glass of water is a physically transparent object that generates the visual sensation of transparency, but a photograph of that glass, being an opaque object in itself (the substratum is an opaque piece of paper), also conveys the sensation of transparency. Summing up, photography represents the spatial distributions of light not by sharing physical features with the objects, but by means of a transformation that brings about a certain kind of similarity. In this sense, we could speak of iconicity (an icon being a sign that refers to its object by means of some kind of similarity with it). This paper will present a survey of these and other semiotic categories involved in photography when representing color and the perceived spatial distributions of light. Introduction As a visual sign, a photograph usually represents an object or a scene; this is the habitual way of seeing it. But it accomplishes that common semiotic task by representing various formal features of the object or scene: its color, shape, texture, spatial distribution of light, or even its eventual movement. The curious fact is that photography does this in very different ways. Our visual world is made of light, because the only thing that our visual system can sense is a certain portion of radiation that gives origin to the perception of light. Light or, more properly speaking, visible radiation is also the physical agent for photography. But our visual system —which comprises all the mechanisms between the eye and the visual cortex— constructs other categories by means of light patterns. These visual categories are usually classified in four or, better, in five groups: 1) Color, that is, the perception of the different spectral compositions and intensities of visible radiation; 2) Cesia, a new category that describes the sensations originated by different distributions of light in space, producing the perception of transparency, translucency, opacity, mirrorlike appearance, matt quality, etc.; 3) Shape, that is, the construction of different spatial configurations starting from the detection of borders between areas differing in color or cesia; 4) Texture, that is, the construction of patterns made of relatively small elements (also detected by differences in color or cesia) that are visually grouped according to certain features; 5) Movement, which implies the perception of displacement of areas or visual elements, either between themselves or all of them with respect to the observer. It has been argued whether photography functions as an indexical sign, because of its necessary physical contact with the objects that emit, reflect or transmit the light patterns that the photograph fixes, or as an iconic sign, because of its condition of being an analogical representation of the visual world (see, for instance, [1-5]). The present paper analyzes how the visual categories described before are reproduced by photography or represented in it. We will see that the consideration of a photograph as an index, an icon, or even a symbol, depends largely on which visual category we are taking into account at each moment. As a conceptual frame of reference, let’s introduce the basic definitions of icon, index, and symbol. An icon is a sign that is related to the represented object on the basis of a certain similarity or some common feature, which may be a similarity of shape, color, etc. An index is a sign that has a physical relationship with the represented object; i.e., a physical copresence of index and the represented object is required, and the connection between both is immediate. A symbol is a sign that has an arbitrary relationship with the represented object; it works by means of a codification; i.e., the knowledge of the code is required to be able to grasp the meaning of a symbol, and the decodification implies a certain timescale of cognitive