2.1.Plastic Variables

2.1.1.Universe of color

Color is the product of a perceptual phenomenon localized at the interfaces of matter which are in contact with air. Any work of visual language achieves existence essentially through color organizations, as does visible reality itself. But, strictly speaking, color cannot be considered as a ‘property’ of matter itself. It consists rather of the spectral composition of the light reflected from an object, according to its specific structure of absorption and reflection of light rays.

From the scientific point of view, color is defined, at the macroscopic level, as the reactive capacity of materials to rays of light. It is by no means redundant to recall that, at the microscopic level, color terms no longer designate a color referent in itself. They are applicable only through an artificial injection of lighting and colorants in order to become the basis of a system of description, where the references to color are purely arbitrary and conventional. Indeed, colors injected in the microscopic milieu do not correspond to colored characteristics of elements, but rather constitute only an artificial instrumentality for the differentiation of heterogeneities and trajectories that do not have color. However the addition of color to these microscopic units allows the perception of internal morphological and functional structures through groups, textures, and so forth which derive from deep structures. Similarly, in outer space, as W. O. Quine noted, color does not have more significant existence: “Color is king in our innate quality space, but undistinguished in cosmic circles. Cosmically, colors would not qualify as species” (1969; 127).

In the macroscopic environment, color terms derive their capacity to designate objects from an accumulation of chromatic mass in diverse expanses great enough to correspond to an optical perception. Within the limits of macroscopic space, the preeminent existence of the coloristic phenomenon has not contributed, however, in any fruitful way to the understanding of the natural world. Even if we live, at the anthropomorphic level, in a space of qualities manifestly “chromatically biased,” this sine qua non character of human experience could never serve as a correlative by which to understand or to describe the surrounding reality with cogent basic hypotheses.

Thus, the fact of color, the most obvious of all facts in sensory experience, cannot serve as a reference in the recognition or the description of constant or regular events. It cannot constitute a concomitant factor sufficiently reliable to help in the understanding of the development of phenomena in space-time. Modern science was constituted, perhaps, by the definitive giving up of the attempt to derive from the color of natural elements, as alchemy tried to, pertinent data concerning their nature and their behavior: “Credit is due man’s inveterate ingenuity, or human sapience, for having worked around the blinding dazzle of color vision and found the more significant regularities elsewhere” (Quine, 1969; 128).

Certainly, at the pragmatic level, as Quine further comments, colors have played a role in the primary definition of the surrounding world, providing provisional identification of useful or dangerous objects for survival; “Color is helpful at the food-gathering” (127). An observation of a colored phenomenon can, at this level, serve to support some inductive generalizations of character, however highly relative. A researcher, H. Yilmaz, has nevertheless shown “how some structural traits of color perception could have been predicted from their survival value” (Yilmaz, 1969; 90), but it remains a rare occurrence.

But even in this restricted domain, still very little explored, the characteristic of color does not serve to distinguish, in any continuous and rational way, those elements essential for nourishment or protection from their opposites. Numerous variations in colors, which would be so important in other sectors of qualitative perception, are not significant and should be neglected to the benefit of other categories, if one looks to establish a science of edible resources for man or animals. Whereas, among other generally observable traits in natural objects, a large number serve to identify species or categories, color, omnipresent as it is, does not constitute most frequently an essential trait from which the universe can be described in any experimental or scientific way.

Color can only be described with some precision outside of spontaneous sensory experience by physics and optical instrumentation. At the level of human perception, it can only be apprehended through the intermediary of ideas of similarity or difference, notions indeed familiar and often used but which science cannot use because they cannot be quantified. As Quine puts the case: “Similarity being a matter of degree, one has to learn by trial and error how reddish or brownish or greenish a thing can be and still be counted yellow” (1969; 121).

This problem has already been recognized in visual arts theory, as evident in J. Veltrusky’s assessment of art historian E. H. Gombrich’s endeavors in this respect: “Gombrich has probably contributed more than any other scholar to the necessary critique of the loose and naïve way in which the concept of resemblance has been used in art history” (1976; 257).

In the 19th century, Chevreul had already classified 20,000 natural tints perceivable by the eye, and there are millions perceptible through scientific instrumentation, depending on the variations of wavelengths, luminosity, degrees of refraction or reflection, and so on (Birren, 1969; 50). Not only is it difficult to quantify that area where a given color would be correlative to a certain definition or to a certain concept of this color, but its necessary position between other colors will modify the initial data that one would have wanted to establish with precision.

This fundamentally elusive character of color, its difficulty in being described in objective and systematic terms, explains why, from such an immediate and common sort of experience, men have taken such a long time in elucidating certain of its foundations and properties. This has led Birren to quote the physicist Maxwell who said: “The science of color must be regarded essentially as a mental science” (1969; 53). The Ancient Greeks themselves could only conceive of a theory of color by borrowing more or less pertinent philosophical conceptualizations. One wonders, for example, about the fact that simple and primary colors were designated by Aristotle as the manifestly complex and unstable colors of natural elements, that is, of fire, of air, of water and of earth. And circa 1666, Newton defined primary colors in relation to the seven spheres or primordial planets.

A long process of abstraction in human thought was necessary to the establishment in the 18th century of a theory of primary colors which appears to the contemporary sensibility as almost evident, that is, the system of colors defined from the generative spectrum point of view. It was only circa 1730 that J. C. LeBlon identified the three primary colors—red, yellow and blue—which, by the mixing of their luminous rays, produced other colors. This proposition was modified at the end of the 18th century, and red, green and blue were posited as the source of composition of others in the ray of light.

At the beginning of the 19th century, Goethe himself, despite his familiarity with the analysis of the spectrum, established in a still more restrictive way the primary colored elements (1976). He only recognized as such yellow and blue, by virtue of an analogy with the phenomena of night and day, thus still treating colors by associations that Wassily Kandinsky was later to qualify as purely literary.

Physical optics proceeded, in the 20th century, with the study of the phenomena of radiation of light, or the composition of spectral light, across diverse types of prisms, which produce approximately 134 to 207 colors, according to researchers. The physiology of vision began, for its part, to elucidate the structure and functioning of the organ of sight and its links with the visual cortex. But these data did not prove to be very fertile for the analysis of the phenomenon of color in human experience, since physiological variations are not parallel to physical variations (Boll; 1962; 23). This phenomenon can therefore only be apprehended through a better understanding of the process of human perception.

However, regardless of the volume and the minutiae of systems of descriptions and of nomenclature of colors, defining their parameters of frequencies, wavelengths and energy, one could never be assured that an identity existed between this physical reality and the color which an observer perceived. The colored aspect of a section of material perceived visually depends on the organization of the perceptive field in which it is situated and not on its own chromatic constitution. As Crosmann had already established in 1953, there exists an indefinite number of rays, of different spectral compositions capable of presenting, for a given observer, an identical aspect at the level of color (Boll, 69).

Furthermore, the two human eyes do not see colors in the same way, in a spontaneous way, before being subjected to a gestaltian type of adaptation (Legrand, 1957; 75). These differences are accentuated with age and are sometimes greater from one individual to the next, because of the coloration of crystalline as well as individual variations of the yellow pigment of the macula lutea, in which the capacities of absorption of short waves vary in the different groups (77).

Not only do the perceptual context and the individual and endogenous mechanisms of perception modify perceived color, but also a given pigment can modify its color in an objective and measurable way, according to the technique of display, dilution and superimposition which is used: “The way of displaying the pigment and mixing it with other colors considerably influences the optic properties of the color obtained, and this in a ‘objective and real’ way and not only as a fact of perception” (Guillot, 1957a; 174).

As soon as a color is expanded on a particular surface, it takes on a certain textural aspect which modifies its chroma in its very structure and perceptual appreciation. While certain colors change when the density of the pigment carrying them is modified, others do not change at all. Moreover, any modification of visual variables, beside that of texture, will involve a modification in the chroma of the color.

Contemporary chemical colorometry has identified more than 50,000 nuances and tonalities of color which it distinguishes through a numerically-based system. Visual semiotics does not choose to follow in this course since any abstract identification of a nuance cannot be referred as such to a region of the visual field where it would be modified by the context.

It is important also not to overestimate the contribution brought to semiotics by various systems of color which more or less schematize both the colored reality of the spectrum and the opaque colored pigments, in order to produce a repertoire based on a generative system of color. The various classifications of color, those of Goethe (1976), Ostwald, Munsell (1969), Itten (1970), Birren (1969), Küppers (1975), have indeed been developed according to certain needs or pragmatic hypotheses. They do not teach us about the dynamic properties of color, their behavior and interactions. This will remain the task that visual semiotics will have to undertake from its own specific point of view.

2.1.2.Dynamism of color

The continuous movements and changes which affect color in the process of perception, observed and recognized for many centuries, have certainly discouraged any early attempt at a systematization or a categorization of colors. In fact, to identify a color within a previously established scale of nuances, tones and tints and to give it a verbal equivalent cannot be of any real assistance in the description of a perceived color, even if possible. As J. Albers has emphasized: “In its visual perception, a color is almost never seen just as it physically is” (1963; 5). In other words, to see a color is to properly perceive modifications that a pseudocolor (that which is defined objectively and a priori) undergoes as soon as it is perceived in a real environmental context. Seeing a color, as Albers explains, is to “see the action of this color, as well as to feel the effects of relations between colors.”

The research of Albers has served to demonstrate not only that one color summons up innumerable different readings, but also that different colors can be perceived as quasi-similar in certain kinds of environments. One could even go so far as to say that a given color does not exist, since an isolated color does not exist and will, in fact, never exist. In all perceptual experience of reality, it is impossible to see one color that is not juxtaposed with or surrounded by another color.

It is also necessary to be aware of the fact that each time one thinks of a specific color, when one speaks, for example, of red or blue in a theory of colors, one is speaking of an abstraction in the same sense that one speaks of roundness. The terms which designate color refer to a concept of mass, that is, to all that participates in the redness or the blueness itself. But this color that we are supposed to see in our mental universe, isolated and equal to itself, never existed and will never exist in external reality. All the reds or blues that we perceive in the world will always be different one from another and also from any abstract visual concept/percept which takes shape in our mind.

To perceive a color or experience a chromatic sensation is a phenomenon of a psychological order born of cerebral activity, from the moment when the process of sight is set in motion by the light stimulus reaching the eye. The fundamental characteristic of this process is first to be uninterrupted, with the consequence that any colors perceived in succession are modified by the preceding ones. It is not indifferent also, when the eye encounters a tone or a precise tint, if it was previously adjusted to a neutral or sombre vision or if, “to the contrary, it had already undergone a color adaptation” (Küppers, 1975; 37).

Indeed, the first ocular fixation on a colored area affords a chromatic impression whose internal dynamism can easily be felt. In terms of fractions of seconds, adaptation to the color is effectuated so that it does not appear the same at the first glance of the eye, at the second, or the third moment. In particular, during a prolonged stare, a nuance will lose its saturation, little by little, as a result of simultaneous contrasts or other interferences. This explains how, for example, the larger the dimension of a red area in a work is, the less there is of red in that work as perception is prolonged.

These movements and transformations in the observed color, which seemingly preclude any attempts at the measurement and quantification to which external reality yields, have caused certain theoreticians of color, such as Itten, to confer on it a somewhat ambiguous status between matter and psyche: “The effects of color belong to the eye of the spectator. However, the most profound and truest secrets of color are, I know, invisible even to the eye and are only perceived by the heart alone. The essential eludes any conceptual formulation” (1970; 21). Similarly, this dynamic character of color does not lend itself well to a phenomenological approach of an always evanescent colored essence. One can believe, with Wittgenstein, that “there is no such thing as the pure color concept” (1978; 1, 73, par. 26e), inasmuch as a pure concept has to be equivalent to a stable identity.

More simply, one must recognize that the strict dependence of a colored phenomenon on the endogenous activity of a perceiver, added to its status of vibratory energy, does not render the percept of color so very much different from other percepts. The color perceived is perhaps only one among the best examples illustrating the structure of any percept. By nature, percepts, as Köhler has pointed out, are totally subjected to the law of change: “In the nervous system, the excitation produced by a continuous stimulus does not remain constant, in general, in time” (1967; 21). This continuous internal transformation, which is amplified by the addition of chromatic interactions issuing from the visual field itself, would explain, undoubtedly, the fact that the memory of colors is one of the most difficult to achieve within the whole family of percepts.

Linked to all the other visual variables and only appearing in unison with them, color depends, in its very structure, on the wave-like and particle-like material which transports it, on light itself, and on the perceptual processes which causes it to surge up from opaque matter. Matter in itself is not colored, but rather colorless, but the double action of luminous rays and perception always presents it otherwise. This therefore is the paradoxical existence of color, a unique construction of human perceptual system, which will be utilized to represent: (1) in a mimetic function, a very superficially colored material reality; and (2) in an expressive function, a human experience which possesses nothing properly colored, produced by the sensory-motor, affective, or intellectual channels which link a man or woman to that reality.

In order to understand and describe this elusive phenomenon, visual semiotics has to use a verbal terminology little adapted to the expression of movement and of change. Linguistics has also developed a relatively inadequate vocabulary for the abundance of chromatic events in reality. Until more knowledge is gained into the structures of auditory and visual percepts, the attribution of certain colors to corresponding concepts of verbal phonematics seems to us hazardous, as does the belief that verbal phonematics can serve to arbitrate in the conflicting problematics concerning the specificity of a chromatic phenomenon (Vallier, 1979).

2.1.3.Nomenclature of colors

The marked incapacity of verbal language to establish the nomenclature of colors is a notorious and distressing fact. Among the many statements to this effect, we may cite that of Harald Küppers: “While man can in general distinguish approximately 10,000 nuances of color, his vocabulary furnishes him with only about a dozen different terms: black, white, grey, blue, yellow, red, green and brown are the essential designations which form the basis of this vocabulary” (1975; 15).

If one considers the general difficulty that human beings have in perceiving unnamed objects and placing them in a system of knowledge or a systematization of their experience, one can understand the reasons for the delay in humankind’s becoming aware of the structure and the referents of visual language. The advances in knowledge in the 20th century do not lead toward any solution to this problem. The magnitude of the needed nomenclature forces scientists to establish more or less universally accepted identifications, through a series of numbers and not verbal terms. Moreover, when scientists use more familiar words, these differ as to the “referential wavelengths” to which they apply them, rendering hopeless any attempt to correlate them to perceptual referents.

The limits of the familiar vocabulary of nomenclature are aggravated by the imprecise and variable character of its modes of application in different cultures and societies. While using the modern guidepost offered by the spectral division of light, linguistics has observed a large number of ambiguities in the reference of morphemes applied to colors in different languages: “Behind the paradigms that are furnished in the various languages by the designations of color, we can, by subtracting the differences, disclose such an amorphous continuum, the color spectrum, on which each language arbitrarily sets its boundaries” (Hjelmslev, 1963; 52).

But similar referents in the perceived object do not correspond to identical morphemes. Thus, the boundary which the English language recognizes between green and blue does not exist in Welsh, and the boundary between blue and gray is equally lacking, as well as that which distinguishes gray and brown in English. In turn, the domain represented in English by gray is, in Welsh, cut in half in such a way that one half is included in the English zone of blue, and the other half in that of brown, according to Hjemslev.

The ancient languages are also distinct from modern languages in the application of morphemes relative to color:

Similarly Latin and Greek show incongruence with the chief modern European languages in this sphere.—The progression from ‘light’ to ‘dark’, which is divided into three areas in English and many languages (white, gray, black) is divided in other languages into a different number of areas, through abolition or, on the other hand, elaboration of the middle area. (Hjelmslev, 1963; 53)

Thus, the field of morphemes related to colors is articulated differently in different languages, undoubtedly through analytic hypotheses retaining inclusive/exclusive divisions which do not derive directly from empirical observations. One could not presume that the Welsh did not perceive, by a different form of colorblindness, optical impressions producing a distinction between green and blue. A similar phenomenon occurs regarding the interpretation of time. Certain languages, such as Danish, offer only a distinction between the preterite and the present, and use the present for the domain that is covered in other languages by the future tense. Other languages, such as Latin, ancient Greek and French, will distinguish several kinds of preterite (Hjelmslev; 54).

It would seem illusory, if not absurd, to try to offer an adequate schema of the field of color which would stem only from the terminological variation of one language, whether French or English. One must establish on grounds other than terminological the fundamental notions which can clarify the chromatic phenomenon in visual language.

Is it necessary to observe that the phonomatic field of vowels would no better provide grounds for a morphological or semantic differentiation of colors. The number and the definition of vowels vary from one language to another and their boundaries are established differently in different linguistic contexts: “Eskimo distinguishes only between an i-area, a u-area, and an a-area. In most familiar languages the first is split into a narrower i-area and an e-area, the second into a narrower u-area and an o-area” (Hjelmslev; 55).

Similarly, in Arthur Rimbaud’s Sonnet of Vowels, we observe an individual experience of projection of a chromatic content associated with phonemes. It depends totally, moreover, on a unique linguistic/cultural context which cannot serve as a viable basis for the development of visual semiology.

2.1.4.Systems of production of colors

The epistemological organization of the field of color has been made difficult because of the confusion which obtains among: (1) the system of color defined by optical science by means of the diffraction of luminous rays through a prism, namely the spectral analysis of color; (2) colors seen as the results of the reflection of natural light on material objects; and (3) colors as they reveal themselves and behave in perceptual experiences. The classical disputes concerning the number and identity of primary or complementary colors followed from a confusion among these three levels, particularly with respect to the nature of “objective” or perceptual colors.

2.1.4.1. PRISMATIC COLORS

In 1796, using a triangular prism, Newton achieved a division of an uncolored luminous ray, producing the group of spectral colors. They represent eight chromaticities: red, orange, yellow, green, blue, indigo, violet and magenta. These colors, constituted of luminous waves, present a particular form of electromagnetic energy. The light waves are not colored in themselves but produce, by a refractive process through a prism, sensations which are perceived by the eye as colors. Among the great number of luminous radiations, the human eye can perceive only those waves whose frequency varies between 400 and 800 millimicrons, but these are not all present in the prismatic division.

Among the prismatic colors, six appear as fundamental and are called monochrome, in that they can be defined by a relatively precise and distinct wavelength. These are: blue, violet, green, yellow, red and orange. Magenta is not monochrome since it results from the superimposition of two zones of the spectrum, the red-orange and the blue-violet. The monochrome or primary colors cannot be seen directly in the natural environment, nor as colored light, nor as colored bodies, because these tints would then be transformed or sullied by other nuances. Outside of the spectrum “only developed technical means permit us to obtain monochromatic colors sufficiently saturated and to render them visible” (Küppers; 66).

This explains the complexity of using as a chromatic model the system of prismatic color and of applying it to colors produced in a totally different fashion. Even here, one must also take into account the fact that no precise nomenclature exists to identify the most important nuances of the spectrum and to apply them to other sectors. Rudolf Arnheim (1954; 348) recalled that in Hiler’s compilation the following series of names was given by different observers to a light frequency of 600 millicrons: Orange Chrome, Golden Poppy, Spectrum Orange, Bitter Sweet Orange, Oriental Red, Saturn Red, Cadmium Red Orange, Red Orange. The same was true of other color frequencies.

If reference to the system of colors produced by the spectrum is reinforced today by the division of light used in television, other media are structured in a different way. Thus, in printing, magenta, yellow and cyan blue which cannot be obtained by mixture, are defined as primary. In other areas, like painting and sculpture, the question is still more complex as it is related to the so-called ‘reflected’ color, allowing a nonluminous matter to be perceived as colored.

2.1.4.2. REFLECTED COLORS

The colors which the eye perceives in the surrounding world are not produced in the same way as those which stem from the refraction of luminous rays through a prism. Colors are, however, always conceived as emanating from luminous rays and considered as radiant energies, vibrations, of which the particulars are apprehended by the eye.

The most recent research on the physiology of the eye has shown the existence of three types of cones or color-receptors in the eye which react to three of the zones of the spectrum: blue-violet, green and red-orange (Küppers; 348). In this way, one could speak of these three colors as being primary at the level of the eye function. But the perceptual origin of color vision has not yet overtaken or modified the prevalent theory, mixing elements from the spectrum theories with those of the reflected color theory.

The theory of “reflected color” proposes that physical, opaque matter (of which pigments/mediums of the artistic practice are a part) is composed of a variety of materials possessing different capacities of absorption and reflection of the luminous wavelengths reaching them, thus constituting visible colors. When all the wavelengths of luminous rays are reflected by an opaque material, one describes the surface as being white; when all are absorbed by the material, it is then perceived as black. When the material absorbs only long waves (those we call red) and medium waves (those we call yellow or green) and sends back or reflects only short waves, these produce the sensation in the brain of what we know as blue.

In the same way as spectral analysis does, the theory of reflected color offers the hypothesis that a luminous ray can reflect simple noncomposed waves, called primary colors and diversely composed waves, called secondary or tertiary colors. The primary colors are conceived as simple, pure and well-saturated. In both the prism and an opaque base, a group of four fundamental colors is said to exist: blue, yellow, red and green (Jacobson; 1948). Through mixing, these primary colors would produce secondary and tertiary colors. Although composed, these can still be considered pure tints if they do not contain any black or white.

This hypothesis created a problem concerning the definition and status of primary colors, since this sequence of production is highly theoretical. As noted earlier, one cannot encounter these primary colors in the natural environment (as reflected by objects or by material constituents of visual language), because they would be largely modified by surrounding light, the effect of shadows, the interaction of colors, the variations of atmospheric strata, and so on.

More important, as Chevreul has already explained in the introduction to his “Principles of Harmony and Contrast of Colors,” the emergence of primary colors is impossible in empirical reality. When light is reflected by an opaque body, there is always the reflection of white light and a reflection of colored light, as Chevreul explains:

It must not be supposed that a red or yellow body reflects only red and yellow rays besides white light; they each reflect all kinds of colored rays; only those rays which lead us to judge that the bodies to be red or yellow, being more numerous than the other rays reflected, produce a greater effect. Nevertheless, those other rays have a certain influence in modifying the action of red or yellow rays upon the organ of sight; and this will explain the innumerable varieties of hue which may be remarked among different red and yellow substances. (43)

In other words, ordinary perception can never in practice see these pseudo primary colors in their pure state, unless one agrees to designate as a primary color the ensemble of nuances, tints and tones which red, for example, can undergo when it is reflected within a real environment.

Historically speaking, this has been the ruling decision. One assumes that an object always possesses a constant, precise and often primary color, irrespective of its reflective behavior or the effects of its environment and illumination. Under the name of “local color,” it has been long assumed that reality presents itself to perception in terms of fundamental and simple colors, which were more real, so to speak, than the actual transformations that they undergo in their environment. Artists produced ideally chromatic objects, as defined by an a priori theory of color. The denial of this constancy of local color, through the works of Constable and the Impressionists, changed the modes of visual representation toward a greater fidelity to perceptual experience (Ehrenzweig; 1967). But even if the perceiving public has finally admitted that a tree can be blue or red and not only brown, depending on the effects of the surrounding light or the interaction of colors, the notion of primary color continues to play a major role in the theoretical dimension of the visual discourse.

In spite of the fact that primary colors are not observable in external reality, they continue to be considered in the sector of reflected colors as the alphabet from which colors are constituted.

In this alphabet each element is considered as remaining identical to itself, like a concept, as long as a definite term designates it. If its conceptual meaning is difficult to produce, anyone can recall its image by the use of its label. It was presumed that human beings could form the same visual/mental image of a color, whether primary, secondary or tertiary, at its point of maximal chromaticity and saturation, and that this “pure” image served as a common point of reference for any citation of a chromatic phenomenon. Characteristics of a concept were bestowed not only on mental images, but also on the memory recall of what would be better described as a percept (Saint-Martin; 1985a).

As pointed out earlier, the mental visual image of a color possesses only a very fragile and ephemeral status in the mind and is different for each person, since this image is constructed of fragments of perceptual experiences disengaged from their context. The mental images, as will be explained later, are subject as well to specific chromatic transformations along the laws of complementarity. Given this perceptual context, it is difficult to imagine what nuance is evoked as a ‘true red’ or a ‘true blue’ by the individual as a response to the hypothetical essence of redness or blueness.

Even when it is a question not of a nuance of color to be remembered in an always identical way but rather of a color to be recognized, a color familiar and often perceived in reality, perceivers encounter great difficulty in fixing characteristics. The pedagogical experiences of Albers (1963; 3) demonstrated how different observers fail to identify, among a certain finite set of nuances of red, that particular red that they know well, for instance, that used in the popular Coca-Cola advertisement.

We conclude that the primary colors play the same role as “good forms” in our individual perceptual systems, inasmuch as they are few and simpler than other colors. Other colors are referred to them in order to accentuate similarities or differences, with a view to simplifying the chromatic organization of the whole visual field. This implicit reference to the primary ‘good’ colors, even if they vary with respect to each individual, serves at the same time to point out the dynamic qualities specific to each.

2.1.5.The hierarchical system of Arnheim

This hypothesis was already partially adopted by Rudolf Arnheim, in his 1954 attempt to elaborate a theory of conjunction and of disjunction between colors. This hypothesis was grounded, as most classical and contemporary harmonic theories, in reference to modes of production of colors. But instead of making assumptions as to an a priori theoretical system, Arnheim strove for a perceptual consensus on the “recognition” of a few saturated colors, mutually exclusive, namely blue, yellow, red. Green could be added, for the sake of those who refuse to recognize its composite character. These chromas, argued Arnheim, are each easily distinguishable from the others because each one, when pure, excludes the others, and none can serve as a transition to another (1954; 342).

The experience of these chromaticities would form the stable “perceptual” basis from which other tints would be measured, their reciprocal relations forming reference points for chromatic movement. Even if Arnheim does not make this comparison, these fundamental colors would be situated at a stable, conceptually absolute level, corresponding to a ‘good color’, with which the usual chromatic deviations would be compared. This good color would serve as a ‘good gestalt’ of the chromatic pole in relation to which variations and chromatic transformations would be experienced and evaluated. With respect to mixed tints which are less saturated, sombre or bright, perception would evaluate their relative proximity, deviation, and distance from the fundamental good colors, which would stand for more stable, substantial, and satisfying ones. Thus, the family of reds (cinnabar, cadmium, vermilion, etc.) would be animated in the perceptual process through their comparison, reconciliation, and the sensation of their deviation in relation to a fundamental red which each perceiver establishes as that which reflects, for him, what is the most red in the red. This good color, which always remains a perceptual pole, is based in part on a subjective requirement and in part on an objective fact, as this color is rarely encountered in the chromatic field.

In contrast with the fundamental colors, all other colors present themselves as a melange, to varying degrees, of two or three among them, by the inclusion of certain of these tints and the exclusion of others. These combinations present, therefore, mixtures of quantities/qualities of chromas, from which Arnheim elaborates the notion of the “dominant” tint for the color which is found preponderant in the mix and that of “subordinated” for the other, reserving the qualification “separated” for the one(s) excluded. The differences between primary colors are seen as producing separations and distances between them, leading in mixed colors to possible discordances or disharmonies.

On the one hand, the less the mixed colors possess common elements, the more readily they appear as separate. However, colors which contain some common elements, like green and orange which share yellow, would always retain the possibility of an internal dissociative movement, given the heterogeneity of blue and of red that they contain as well.

The relations between mixed tints would offer the structural possibility of being perceived as near or far, or in conflict, depending on the particular quantities that combine with each of the fundamental colors. Between two mixed colors, harmony would be established, Arnheim proposes, according to the common fundamental color that they contain, which plays a structurally isomorphic role as dominant or subordinate. If in one the fundamental tint plays a dominant role and in the other serves as subordinate, the asymmetry of functions would create for the spectator a discord which would be seen as unharmonizing. This absence of harmony would constitute an imbalance which stimulates perception to produce other centrations in the visual field, in view of attaining a desired equilibrium.

Arnheim (1954; 342-343) gives the example of the following chromatic mixtures of two colors, where the priority position of a term in the pair indicates its dominant role:

Thus, in the blue/red mixture and the red/yellow mixture, the relation of dominance is inverted while in the central column, for example, the fundamental colors would be positioned, ideally, as equal in the constitution of mixtures; this could be a model of an “ideal” secondary color.

Unfortunately, as we will develop later, the human eye does not seem to possess the capacity to recognize either the specific components of a mixed color, or their chroma, or their respective quantities. But the most significant gap in this harmonic system stems from its failure to take into account the fact that color is always modified by the visual variables through which it appears. It fails also to consider the impact of other characteristics of color beyond that of chroma, such as luminosity, saturation and complementarity.

In general, the theories of harmony which seek to provide a rationale, however unsuccessful, of characteristics of prominent works in visual representations are based on the existence of some common characteristics between the colors used. Thus, Itten (1970) foresaw the possible accords between dyads and triads and Ostwald, as Arnheim explains (1954; 335) proposed that harmony would exist between two colors if there is an equality in their essential elements. However, Ostwald only considered as essential chromatic identity and saturation, and not luminosity, and ignored the influence of chromatic complementarity as well as that of other visual variables. Only the colors which face one another in the circle of colors that he has established would be truly harmonious. This proposition does simplify but also considerably restricts the problem of harmony of color in visual works. For his part, Munsell (1969) bases harmony on the principle of an element common to two colors, but one which is realized on the principle of compensation, since the greatest luminosity of a color balances to the weakest luminosity of another.

We believe that these chromatic theories cannot be experimentally verified. Not only do they extract the variable of color from other variables which transform it such as dimension, texture, and so on, but they do not relate it to the other influences always subjectively attached to the process of perception. Thus the chromatic component of saturation is not apprehended in the visual field according only to the norms of a system of production of colors. In the domain of figurative art, in particular, it is obvious that saturation is not apprehended in itself but in relation to external objects that are represented. As Arnheim pointed out: “a red can seem lighter as the color of blood but very dark when it refers to a blushing complexion” (1954; 337).

Indeed, the figurative representation continuously puts in play the concepts of norms or of good color, which is foreign to the dynamism specific to visual variables or to any harmonic theory which seeks a foundation for chromatic organization. We know that, from the beginning of the 19th century, Chevreul (1981; 145) claimed that, in the art of tapestry, which was at the time devoted to figurative representations, “the harmonies of contrast of colour must generally predominate over those of analogy”—that is, of resemblance with the colors attached to the natural objects serving as referents.

The plastic variable of color is therefore subjected not only to the composition of rays reflected by matter but also to the interactions between a colored area and surrounding colors and also between human visual experience and the field of color.

The difficulty in relating a perceived color to an ideal scale is so great that one could better substitute for the term of ‘color’ the expression ‘effects of color’, since a color perceived or remembered changes with its support, its environment, and its function. It is also fitting to observe that the chromatic division into six terms (primary and secondary) is obviously sketchy and far too abstract to support any theory of chromatic correlatives to human vision. Other categories must be added, mainly the tertiary colors obtained by mixtures of primary and secondary colors. But instead of considering these as labels of identification, it is necessary to see them rather as limiting notions, poles with difficult-to-assign boundaries, or as terms of mass, relative to a color in which, in varying degrees, observable phenomena of visible reality participate.

Accordingly we believe it important to substitute for the notion of primary/secondary colors the notion of chromatic poles which we feel can more readily account for the chromatic phenomenon.

2.2.Chromatic Poles

The prevailing state of affairs in the perception of chromatic phenomena prohibits the establishment of a system of colors and of relations between colors on qualities defined as absolute, constant, and precisely isolated. Rather than attempting an impossible synthesis of already-existing systems of colors (which respond, indeed, to other needs), or establishing a repertoire from the variations of nomenclatures in various languages, or even inventing a different vocabulary to designate colors (of which the referents would vary according to the experience of each), visual semiotics will propose a system of description of chromatic phenomena which will rest on two basic postulates. The first is inspired by the most recent hypotheses of the neurophysiology of vision which define the receptorcones of color as reserved not for the activation of one color alone, but rather for a whole range of colors, a cluster of nuances relating to a colored pole and presenting common characteristics: for example, red receptors react, for that matter, to vermilion, carmine, minium, etc. Thus, we will speak in this case about the red chromatic pole.

The second postulate rests on the research of Berlin and Kay (1969) into various primitive and advanced societies, which established that a dozen chromas (of Greek, Xpomos, color) are recognized and named in a universal manner everywhere in the world. This list is perhaps not complete since the authors have refused to recognize as colors those terms which were linked to a concrete object existing in the world. Moreover, while recognizing the difficulty of defining a society as primitive or sophisticated in terms of technological development, these authors point out that the more developed societies recognize and differentiate verbally a greater number of colors. Visual semiotics will propose that these colors, recognized and named by all human beings, constitute specific chromatic poles, each different from the other, rather than entities defined and named according to one hypothetical and unique chromaticity. In this sense, each of the names of the primary, secondary, or tertiary colors must be considered as having a plural referent. When, for instance, the interlocutors of Berlin and Kay classified a color under the rubric of red, it cannot be presumed that they thought of “this” specific red when they heard the term “red”—but rather of one of the multiple reds which lean toward this chromatic pole.

Considering, moreover, the chromatic practice employed in the visual arts, visual semiotics will recognize thirteen chromatic poles, two more than Berlin and Kay proffered, and consequently a greater number than the eight colors specified by Bertin for graphic semiology (1973; 20).

These chromatic poles are red, blue, yellow, green, orange, violet, ochre, purple, brown, rose, white, black, and gray. This basic list regroups those colors called primary, secondary, and tertiary, defined not by additive or subtractive processes of natural light or by processes of electronic production or printing, but rather by the empirical experience confirmed by observation of artistic praxis dealing with the light reflected by an opaque body.

These chromatic poles regroup, therefore, the earlier established primary and secondary colors: red, blue, and yellow and green, orange, and violet, and incorporate the tertiary colors as composites of a ‘simple’ color and a secondary color. Thus, purple is the result of a mixture of red and violet, and ochre, of yellow with orange. Brown also constitutes a specific pole with the combinatory variations in its composition: orange/blue, yellow/violet, and so on.

Further, this list affirms the chromatic character of white and of black which thus become chromatic poles independently of their tonality value, that is, of their capacity when incorporated within another color to render it lighter or darker. We believe that from the refraction of luminous rays, as well as normal perceptual experience, one cannot maintain the hypothesis of Mondrian (1967b) which would make black and white non-colors. In luminous rays, white represents the sum total of colors and black, their total absence, because they represent the presence or absence of illumination. But white reflected by an opaque material is never an absolute brightness or, in other words, a total absorption of luminous rays. As Goethe observed justly, white can only be seen as “the first, opaque occupation of space” (1976; 61). Even if white represents the lightest of colors, it cannot be identified with uncolored light, because it offers variations which permit the distinction of graduated scales of whites, more or less clear, or more or less refractions of other chromas: lead white, eggshell white, and so on.

Similarly, black is always a colored mixture and not a total absence of reflected light. Artistic practice has always understood this fact, as attested to by Largilierre’s teaching to his pupils, at the end of the 17th century, of the modes of fabrication of at least a dozen different types of blacks (1981). Even a philosopher like Wittgenstein (1978; par. 152, 36e) perceived that at least two different color names would be necessary to designate a shiny black and a matte black.

Just like other colors, white and black require, for their perception, an illumination/lighting of a material by luminous rays. Without lighting, they, like any other chroma, cannot be perceived; their perception is linked, even if it is in different proportions, to quantities of luminous rays that their carrying material absorbs and those which they themselves reflect. This does not imply in any way that the chromatic nature of white does not in itself exist and that it is only the result of illumination. This has been shown by research into the constancy of color: “If, for example, the degree of whiteness were a simple function of the intensity of reflected light on a surface, then a white paper in a reduced light would appear darker than a black paper illuminated in an intense way” (Gelb; 197). And this is precisely what is not produced. It is necessary, therefore, to conclude that white and black each possess, for perception, a color aspect which makes them real chromatic poles.

Certainly, the status of black and white remains special since, besides offering a particular chromaticity, they can in a systematic way, when mixed with other colors, make those very colors lighter or darker, thus modifying most of the other dynamic characteristics of those colors. We will discuss this at length in the later chapter on the phenomenon of tonality and its repercussions for the law of successive and simultaneous contrasts.

It should be pointed out that all the colors belonging to regroupings of chromatic poles can also be called clear or dark, according to their own register and independent of any intervention of white or black in their constitution. This characteristic of light or dark in chromaticity is not easily expressed in words but involves highly important kinesthetic and tactile effects which influence visual organization. Albers noted the double status of this notion: “the darkest color is visually that which seems heavier or that which contains more black, or less white” (1963; 13).

We include, moreover, among the chromatic poles, following the observations of Berlin and Kay, the chroma known as pink, which has been denied this status until now, since it seemed the result of a tonal modification of red. We also include gray as a specific pole, though a certain technical vocabulary applied up until now to a large number of secondary and tertiary colors, even if they contained neither white nor black. This chromaticity represents, for us, the passageway between white and black.

The notion of chromatic poles is heuristic because it avoids the sub-stantialist concepts that are often associated with a vocabulary which uses the notion of primary colors in the sense of pure colors without mixtures. The chromatic poles can be analyzed and described according to the most significant characteristics of colors: namely, chromaticity, saturation, tonality, luminosity and complementarity.

2.2.1.Chromaticity

Chromaticity designates the specific sensory characteristic which distinguishes a color and differentiates it or opposes it to another color. It is maximal when one gives the maximum density to the application, for example, of a given pigment. Thus, a first layer establishes a chromaticity but may leave zones more or less laden with pigment; another layer provides an area, in a compact way, with zones more and more dense with this particular color. However, a point of optimal saturation exists, after which any addition of the same color will set in motion a tendency toward blackening; the effect is inverted if too small a quantity of pigment is used within a color. In the same way, the smaller a colored region is, the less it is saturated with its own chroma (Galifret, 1957; 43).

The chromaticity of a color diminishes also when one incorporates white or black, or when it is under the influence of too much or too little illumination.

2.2.2.Saturation

Saturation is the maximum level of chromatic intensity that a color can reach without being transformed into another color or without diminishing radically its particular quotient of vibrations.

Saturation results not only through the mode of application of a color but also through interrelations established between a given color and those which surround it. These interactions between regions of a polychromatic field can diminish or augment the saturation of a color at the same time as they transform its chroma. Chromatic saturation must, therefore, appear as a limit which, if it cannot be measured by scientific instruments—since it is transformed in the perceptual relation—does play a considerable role in the organization of the visual field.

2.2.3.Tonality

Tonality appears to us as a proper characteristic of color, inasmuch as it is defined as a quantity of light and darkness brought to a given color by its admixture with black or white. In using the vocabulary of Chevreul (1981; 78, par. 5) and not the more recent and quite varied usages, we will call a color mixed with black a tone and a color mixed with white a tint.

Altogether distinct vibratory phenomena exist between dark colors at their point of saturation and colors which become darker by the intervention of the color black, that is, by a different family of reflected rays. This holds true as well for white and the admixture of white chroma with reflected waves of another chroma. The phenomena of tonality have played a major role in the traditional teaching of drawing because of their functional role in the production of volumetric illusion. They have sometimes been identified with the notion of “values,” in the description of a visual work, although they have always only been complements to the efficacy of chromatic values.

2.2.4.Luminosity

Luminosity designates the intensity of the vibration of luminous rays which perception detects in every chromatic region. On the subjective level, it is linked to the particularity of the nervous influx which connects the retina to the visual cortex (Monnier, 1957; 17). On the objective plane, it is derived from the interaction between reflected waves of white light and of colored light of variable wavelengths and frequences in a perceived region. It is also the result of interactions among reflected waves of one region and those of surrounding regions in the visual field. These interrelations among varied wavelengths at the heart of reflected rays are perceived, in color, as a vibration or in other words, as a dynamic activation which modifies the characteristics of this color in its relation to others.

A color will be all the more vibratory, expansive and radiant as it has more luminosity. This luminosity does not depend only on its physical structure and relations with surrounding colors but also on the type of dispersion that a color has undergone. Particular vibrations can be obtained by what has been called among artists the “touch,” or the synthesis of the speed, length, tension, matter, and composition present in a brushstroke. More sophisticated means will play on the superimposition of one tint on an analogous tint, and so on.

Carried to its maximum, luminosity becomes a sort of radiance which does not seem to be attached or restricted to the dimension of the region where it appears. As Rudolf Arnheim expressed it, “We associate radiation with an absence of surface texture. Objects appear opaque and solid by their texture, which establishes the boundaries of their surface. But a radiant object does not stop the gaze in fixing it at this external threshold” (1954; 315). Its limits are not defined by the eye. The object seems to be overlaid by a film of color rather than to present a surface of color. Light seems to take origin in the object and at a distance removed from the perceiver. “All luminosity which appears strong in relation with its environment tends to eliminate surface texture; and an absence of texture will favor the effect of radiance.”

A more luminous color recedes in depth, and colors of the same luminosity regroup in perception. The contrast between two colored regions depends more on their different luminosities than on their chromatic diversity: a red figure on a green ground becomes indistinct, if the two regions have an equal luminous intensity. The luminous equality then dissolves their boundaries (Monnier; 17).

This points to the important role played by luminosity in relations established between coloremes through the dynamism of their boundaries and chromaticity. Dark colors, in effect, which contain or do not contain black, all reflect a variable luminous intensity which modifies the interaction between these and surrounding colors.

One must not confuse the luminosity of a color, which is the effect of the luminous vibration constituting it in relation with vibrations of colors which surround it, with the illumination which results from a particular lighting emanating from the exterior of a visual work and which renders it visible.

The constancy of chromaticity and luminosity under the influence of varied illumination has long been an object of study in the psychology of perception. David Katz (1935) in particular, not only established clear correlations between the color of an object and that which the lighting creates, but also developed a dual gradation of characteristics (insistence and accentuation) for white and black regions subject to different sources of lighting: “. . . that which is the most illuminated of the two colors is always the most insistent but not always the most pronounced . . . One can therefore affirm that there are not two surfaces of the object which can be perceived according to the same color when they are differently oriented in relation to the light source” (Gelb, 1967; 198).

The different lightings or illuminations transform the chroma of a color because they interfere with the ensemble of reflected waves. As Hans Wallach (1961) specified: “The quantity of light reflected by an opaque object and which stimulates the eye depends not only on the color of the object but as well on the quantity of light which falls upon the object, on its ‘illumination’.”

This led to the recognition of a constancy of luminosity, as when an object will seem to have the same color under different lightings, that is, when the colors seen will be similar to those which are perceived under the illumination of white light.

A too-bright illumination originating from the exterior and shining on a visual field can dissolve and destroy the chromaticity of regions on which it falls. In all cases, changes in lighting sources modify the color of a region. The case is the same with what is called “natural lighting,” paradoxically considered constant, when the spectral composition of daylight coming from the sun is subjected to constant variations. The position of the sun at its zenith, at high noon, offers an elevated proportion of short waves which lend a bluish reflection, while the movement that it makes in an oblique position will give a more reddish and warmer lighting. In a house, a studio or a museum interior, the luminous sources always represent a range of extremely wide variations which are capable of transforming, with luminosities and chromaticities, all the internal organization of a visual work.

One must not confuse luminosity—nor the effects of lighting emanating from a source external to the visual work—with the effects of the mimetic fiction of a source of internal or external lighting in the visual representation itself. Both freeze represented objects in an immobility opposite to the very dynamism of the visual field. At its most simplistic level, this effect of external lighting can be produced by the direct use of white and black which mimics the brightest points of a volume or zones of shadow. At other times, the introduction of white and black in colors, producing a tonal gradation in relation to a source of light, may simultaneously destroy chromaticity, saturation, and luminosity.

These effects of lighting, added to the dynamism of colors, have as a principal function the hollowing out of spatial volume, according to alternations of shadow and light. Lighting also produces an illusion of external Euclidean volumes, according to points of view determined by the position and distance between the object and a supposed source of lighting. The adjoining to a pictorial mass of a projected shadow will have the same effect of constitution of volumetrics, while the distinctive contrasts between dark and light regions will produce effects of superimposition between regions.

The developments in pictorial art, since the beginning of the 20th century, have been based on a rejection of the simulation, in the visual representation, of sources of lighting foreign to the internal luminosity of color, which would mimic scenes of external reality. There has also occurred a rejection of tonal contrasts which reduce the intensity of colors themselves. This has been explained by Hans Hofmann: “Since light is best expressed through differences in color quality, color should not be handled as a tonal gradation to produce the effect of light” (1948; 68).

2.3.Complementarity

Complementarity is, like luminosity, an “immanent” characteristic of the phenomenology of color. Chevreul explained it thus: “To put color on a canvas is not simply to color the surface where the paintbrush has been applied with this special tint, but it is equally to color the adjacent space with the complementary of this color” (In Blanc, 1880; 563). This subjective perceptual phenomenon means that any perception of a color necessarily involves the projection by the eye, in the visual field, of another color, called its complementary.

This physiological phenomenon is constant and even children, in their drawings, respond to each color or group of colors by using the complementary color.

This visual movement has been explained by various hypotheses, some seeing it dependent on “retinal fatigue” or the wearing out of the chemical quantities which constitute the diverse receptor-cones of colors, thereby provoking the surrounding cones to a greater activity. Goethe added to this explanation the “law of completeness,” according to which the eye, aspiring to see the totality of color, fills up the registers of luminous waves absorbed by bodies and not presented in a colored reflection. He wrote:

When the eye sees a color it is immediately excited and it is its nature, spontaneously and of necessity, at once to produce another, which with the original color comprehends the whole chromatic scale. A single color excites, by a specific sensation, the tendency to totality . . . To experience this completeness and to satisfy itself, the eye seeks for a colorless space next to every hue in order to produce the complemental hue upon it. (317, par. 805)

Goethe called this need for a chromatic totality felt by the organism the “law of completeness.” When the eye realizes through perception one of the fundamental chromatic possibilities, it immediately searches to see or to produce in the visual field the emergence of other colors reunited in the complementary, in order to recreate the chromatic totality:

We stated before that the eye could be in some degree pathologically affected by being long confined to a single color . . ., the demand for completeness which is inherent in the organ, frees us from this restraint; the eye relieves itself by producing the opposite of the single color forced upon it, and thus attains the entire impression which is so satisfactory to it. (Goethe; 319, par. 812)

Similarly, the artist will be essentially engaged in strategies to provoke, distinguish, and satisfy this demand for totality that man cannot gratify in the contemplation of nature: “Nature perhaps exhibits no general phenomenon where the scale is in complete combination. By artificial experiments such an appearance may be produced in its perfect splendour” (Goethe; 320, par. 814). The rainbow itself does not offer an example of the totality of colors, “for the chief color, pure red, is deficient in it, and cannot be produced, since in this phenomenon, as well as in the ordinary prismatic series, the yellow-red and blue-red cannot attain to a union” (Goethe; 320, par. 814).

Through these links with the psycho-physiological process of perception known as successive and simultaneous contrasts, Goethe established a coherent theory of aesthetics, based upon a specificity of visual language and its capacity to structure a dynamic space in three dimensions. The production of complementaries, in creating new junctions between regions and modifying their reciprocal positions, institutes a topological mass possessing a differentiated and shifting interior volume.

The theory of complementary colors, having been constructed on a hypothesis of primary colors, will vary according to the historic variations of the definition of these primary colors. Newton spoke of seven colors, Goethe and Schopenhauer of six, Ostwald of eight, Munsell of ten. Goethe defines the principal complementary colors as being: red-orange and blue and vice-versa, red and aquamarine green, violet and leaf green. Munsell (1969) defined complementary colors as being the pairs yellow and purple, blue and orange, red and blue/green, purple and green, and so on. Newton mentioned, on one occasion, the complementary relation of gold and indigo. These variations do not question the reality of the phenomenon of simultaneous or successive contrast. They only reveal the diversity of the experiential phenomenona of color in a visual field. Albers neatly summarized this complexity in saying: “The complementary of a specific color, when it plays into different systems, will appear different” (1963; 41).

These divergences also reflect the difficulty encountered in obtaining the necessary material pigments to reconstruct the phenomenon of total color reflection, as exemplified in the ray of light. Optical theory defined complementary colors at the level of luminous rays as those which, superimposed or added, yield an effect of white, that is, the totality of wavelengths composing the colorless luminous ray. This definition was adopted by several aesthetic theorists, from Charles Blanc (1880; 561), who evoked in his Grammaire des Arts du Dessin this totality of white light, to Munsell, who spoke of the production, within systems of color, of an equivalent to that white light in the realm of reflected colors: perfect gray (1969; 28).

Borrowing the model of optical colors was predominant in the field of visual arts. Theoretically, as Charles Blanc wrote, “we have therefore called ‘complementary’ each of the three primitive colors in relation with the binary color which corresponds to it” and “reciprocally, each of the mixed colors, orange, green and violet (produced by the mixture of two primitive colors) is the complement of the primitive color not used in the mixture; thus orange is the complement of blue, because blue has not been used in the mixture which formed orange” (1880; 561). This widely disseminated formulation, based on the additive properties of lightwaves, has remained prevalent, even though the electronic composition of color imposes another opposition, being that of yellow as the complement of blue. We are more aware today that there exist hundreds of identified shades of reflected red, blue, and yellow, which contain other chromatic components and will produce correlatively varied types of complementaries.

The law of complementarity is very easily observable when a colored surface is positioned on a white or grey field, producing a clear chromatic aureole or the strong emergence of the complementary color. The complementarity will be manifested, also, in relation to the phenomenon of tonality, that is, a dark region involves the projection of a luminous zone to its boundary and a clear one accentuates the darkness of its immediate surroundings.

It is widely recognized that two complementary colors, when placed side by side, will each heighten the other, will vibrate or shine all the more, and will reach the maximum of their chromatic intensity. The complements will also play a major role in the organization of the spatial field, because the eye, seeing a certain color, will spontaneously search for and be drawn to that color’s complementary which might be found in another place in the field. This remarkable phenomenon implies an attraction between colors which is no longer based on the gestaltian law of similarity, but rather on heterogeneity. On the visual plane, complementary colors will spontaneously regroup for the eye in a particular succession or binding group. This effect is so strong that, when complementary colors are juxtaposed in a smaller region, they tend to regroup in an autonomous fashion and isolate themselves from the ensemble, thus creating a disjunction in the spatial fabric.

However, when the complementary of a given color is not found in the same visual field, an extremely strong tension is immediately created for the perceiving eye and ineluctably results in the production of simultaneous and successive contrasts of color and tonality.

Nevertheless, despite this changeable multiplicity, constants of transformation have been defined which, when applied to circumscribed elements, modify the chromatic regions in a regular manner.

2.3.1.Laws of interaction of colors

The regularity of the process of interaction between colors, arising from both chromatic materials and the mechanisms of visual perception, has resulted in the formulation of various laws which articulate syntactic rules defining the relations between the elements of visual language.

2.3.2.Laws of equalization

The most general law regarding colors, movements, or transformations follows the parameters of gestaltian observations which posit a universal tendency of stimuli to be transformed in order to attain a similarity or a homogeneity, or to recover a predefined totality/completeness. In the first case, the phenomenon of equalization refers to changes happening among several different surfaces, so that an attenuation of their differences is produced. This visual movement has been particularly studied by C. Musatti (1957; 94): “The surface which undergoes the equalization on the part of another surface is enriched by a chromatic or brightness component which corresponds to the color or the brightness of the other surface.”

This phenomenon of equalization is facilitated for surfaces seen as parts of a unique figure, that is, in a gestaltian or formal totality. The effect of chromatic equalization has been commented on only marginally in texts on color because this visual movement seems to contradict the laws of simultaneous contrast. It is not the case, however, since one and the other are produced in specific states of the visual field and a passage from one to the other is a frequent phenomenon. The emergence of works of the Op Art movement in the 60s have made this effect familiar to us.

It is produced especially, in fact, when short or long linear masses of different colors emerge on a homogenous chromatic surface. Thus, a red surface crisscrossed with blue lines becomes violet-like, or orangeish when crisscrossed by yellow lines. But this effect is also produced between several differently colored surfaces; if these colors are contrasted, a neutralizing effect will be felt by the heightening of tints which are common to them.

Musatti determined that this effect is constant but that it can be stronger when; “the relation between the general extension of a surface and the development of its contour is very small, the action that this surface exercises upon another contiguous surface is an action of equalization instead of being an action of contrast” (95). But occasionally a lengthier observation can produce the inversion of the equalization in contrast. In the same way, “there exist situations where a colored surface exercises on a contiguous surface an action of equalization, while undergoing on the part of this same surface an action of contrast” (Musatti; 99).

It so happens in a bichromatic square, where a red field is crossed by prolonged yellow strokes up to the periphery, that reds become more violet and yellows more orange.

The phenomenon of equalization does not transform only the chromatism of the neighboring region and, by that, all the plastic variables which are dependent upon it; it acts also on the global perceptual field and spatially transforms it, in the same way that blurred contours do: “The phenomenal aspect of yellow and of blue brought upon a grey is very particular; it is a little as if there were a yellow and blue powder on the grey” (Musatti; 95). Inversely, a gray powder will appear on the blue and the yellow.

As is the case with all visual movements, the effect of equalization is not produced if the percept is interpreted in relation to a concept of an objective, external object, the notion of “real” objects not permitting the development of syntactic interactions between elements of visual language: “This equalization is not produced for colors seen as colors of objects, but for the chromatic components which produce the impression of luminosity, or the general chromatic level of the visual field” (Musatti, 1957; 99).

This chromatic equalization produced in a field seen as unitary, “would represent only a particular case of this law of perceptive homogeneity” (Musatti; 100) which, on a more general level, would furnish the foundation of simultaneous contrasts themselves in spite of their apparent contradiction.

2.3.3.Chromatic simultaneous contrasts

The chromatic simultaneous contrast, also known as “antagonistic induction,” is the phenomenon which results when a chromatic surface contiguous to another surface of a different color is enriched by a component antagonistic to the color of the second surface. As mentioned before, these antagonistic components have been called complementaries, since their juxtaposition in a luminous or opaque milieu reconstructs white light or neutral grey respectively.

The existence of two types of simultaneous contrasts, tonal and chromatic, extensively treated by Goethe in his Theory of Colors of 1810 and explained under the form of laws by Chevreul in 1839, seems a permanent and indisputable acquisition in the field of visual perception. Considerations about these simultaneous visual movements between two regions are an indispensable element in the thinking of all 20th century theoreticians of color (Itten, Birren, Ostwald, Küppers etc.). But a few among them, perhaps because they found these laws too obvious, have dedicated to this phenomenon the type of exhaustive examination undertaken by Chevreul, to which we must again refer the reader in order to complete our brief observations on chromatic phenomena. In fact, most modern theoreticians, given their didactic and pedagogic concerns, or their desire to rationalize and simplify an elusive subject, have a tendency to schematize the essentials of these laws, so as to be able to disregard their troubling consequences. Inspired undoubtedly by his artistic practice, Albers, who was also an eminent teacher, even if not entirely explicit on the theoretical level, has greatly deepened our understanding of this subject through continued empirical investigations that qualify as truly presemiotic. Above all, he has demonstrated the changing and pluralistic character of chromatic phenomena and of the simultaneous and successive contrasts that color continuously produces.

Gestaltian scientists established some decades ago that simultaneous contrasts of color and of tonality are part of any experience of the visual field. In Köhler’s words:

Take color vision: when a gray object surrounded by a white surface is compared with a second object that, physically, has the same gray color but is surrounded by a black surface, the gray-on-white object looks darker than the gray-on-black object. Similar effects of the color of the environment on a local color can also be demonstrated when the surrounding colors in question are so-called hues, that is, red or yellow or green or blue. In a red environment, for instance, a gray object tends to look greenish, and so forth. (1969; 41)

The basic phenomenon which supports this theory refers to the fluidity of visual percepts and more specifically, to the fact that any colored region sees its color modified by the continuous effect of an ocular fixation. The gestaltian laws clarify the nature and direction of these chromatic changes, through which any simple color, if such ever existed, which is an object of perception is modified so as to become a composed or mixed color.

According to the traditional law of simultaneous and successive contrasts, when the eye perceives a given color, a reaction is immediately produced by which it projects on this very color, and more so on a neighboring region, its complementary color. If the eye perceives blue, it projects its complement, orange; if it sees red, it projects green; if it perceives yellow, it projects violet. Or, if the eye sees a red region, situated in the visual field beside green, this latter green will become much more intense and saturated, acquiring new dynamic properties. If the first region is blue, and the neighboring one yellow, this one will seem to be overlaid by an orange “film,” undulating, penetrating and moving finally over both regions.

The projection of the complementary color approximates the status of a transparent color because it does not appear as being quite connected to the underlying surface. The term “film” tries to indicate the way in which it is spread out upon other surfaces, analogous to the manner in which Katz (1935) made the distinction between surface and film colors. The surface color appears to ordinary perception as hard and easy to localize on any plane, coinciding with the contours and the position in depth of the region. But the film of color most often presents itself on a frontal parallel plane, often in contrast to underlying regions, and seems to hover above it as a moving, indecisive plane, somewhat penetrable to the eye (Itten, 1970; 15).

Chevreul had already demonstrated that, when two planes of primary color are seen in juxtaposition, each of these planes is subjected to the addition to its own chromaticism of a movement toward the complementary color. Thus the perception of two regions, one red and the other yellow, will produce a tendency for the red to become violet and for the yellow to become green; or, again, the perception of two regions, one yellow and the other blue, will make them change respectively toward orange and indigo.

When two juxtaposed colors are a primary and secondary color possessing a common color, the modification brought about by the projection of the complementary color will act to subtract that common color in the two regions. Thus, when two regions offer blue and violet, the modification will involve the blue towards green and violet towards red, with a weakening of the blue which is their common color. This explains why two colors which are part of a range or gamut of colors belonging to a certain pole, like blue/violet or red/orange, will be more differentiated in a juxtaposition. Furthermore, in juxtaposed red and yellow, the simultaneous contrast will remove any yellow that might be contained in the red, pushing it toward violet, and diminish any red in the yellow, to push it more toward green. Thus, when two mixed colors having a common color are juxtaposed, they lose their common color so as to appear even more differentiated.

When complementary colors are juxtaposed, each becomes more intense and saturated, but also more stable or inert because they are less susceptible to chromatic modifications, since complementarity has already been achieved in perception.

The juxtaposition of a color to a white region makes the complementary immediately appear clearly; thus when an artist puts a color on a white paper or primed canvas, he has colored the adjacent field with the complementary color. In the same way, the juxtaposition of a color to a black region produces a complementary in the black region, that is, a coloration by the complementary of the light still reflected in small quantity in this region even if few colored rays pass through.

When a gray region is put on a colored ground, it is immediately tinted by a film corresponding to the complement of the colored region. In this case, a region of medium size is more affected by this transformation than a very large region.

The effect of simultaneous contrast is felt starting from the zone where the colors are differentiated, that is, from their common boundary. However, simultaneous contrast can also be experienced more or less between two regions which are separated and at a distance from one another in the visual field, since the visual centration can pass rapidly from one to the other. In a general way, the more that regions offer clear and neat contours, the more the simultaneous contrast will be effectuated. If the boundaries are blurred and toned down, the effect is dissolved for both tonal and chromatic contrasts. In diminishing the neatness of contours and in substituting a gradual transition of intensity, “we can expect that between the two zones is established a process of reciprocal interaction and phenomenally the respective clarities tend to be equalized” (Kanizsa, 1957; 113).

It is impossible to deduce a priori, outside the experience of perception of a given visual field, the chromatic transformations produced by simultaneous contrasts of colors, following a simple verbal labelling of colors which are present there. This is a result of the fact that projected complementary colors are modified according to the real composition of colors and not according to their dominant chroma. The eye, as has been noted by all authors since Chevreul, is incapable of consciously recognizing the nuances which compose a color offered to perception, that is, the real components of a so-called primary color or of a composed color. As expressed by Itten, “we cannot perceive the nuances in a composed color. The eye does not resemble the musical ear, which can distinguish each of the individual tones in a chord” (Itten, 315). But the eye does respond perceptually to those components.

2.3.4.Simultaneous contrasts of tonality

The law of chromatic contrasts posits that, under constant conditions of illumination, all colors undergo considerable variations as a consequence of perceptual centrations and action of neighboring colors. Similar phenomena are produced in the domain of tonality. But it is not always easy to distinguish, in the changes which black and white produce or which they undergo, that which depends on their chromatic quality from that which depends on their quantity of dark or light.

The visual movement provoked by the inscription, for example, of a black form in a white environment, or the inverse, produces the effect of a figure on a ground, that is, a separation in depth between these two elements. This depth is less pronounced, but is always present, when these two elements tend toward a gray of the same value or tonality. But, at the same time, the mechanisms of tonal contrast will be deployed, accentuating or diminishing the quantities of clear or of dark on affected regions and modifying their apparent dimension, density, or saturation, and their distances in depth.

The most important effect created by the tonal contrast is the accentuation of the clarity in the region which surrounds a black form, and the accentuation of the darkness in the region which surrounds a clear form. As expressed by Goethe: “. . . If we look at a black disk on a light gray surface, we shall presently, by changing the direction of the eyes in the slightest degree, see a bright halo floating round the dark circle” (11, par. 30). This phenomenon is produced around all possible forms and not only circular forms and with all colors which are darker than their environment.

When two grays are placed side by side and perceived as such by the eye, an accentuation of the difference between the two grays is produced; in other words, the darker gray will appear even darker, the light gray lighter.

Köhler observed this modification of tonalities when different tones are juxtaposed, notably in the case of a gray object set in a light or dark environment. The two levels of gray are perceived as different functions by the rods of the eye which assure the perception of differences of luminous intensity or tonality, while the cones react to colors. These rods, tinted with a red ingredient, are decolored, little by little, under the effect of light, changing to orange, yellow and white. This process of decoloration corresponds to an energy-generating process and sets in motion physiological excitation. When a luminous stimulus ceases to act, the pigment of the rod is regenerated, thus recovering its proper perceptive properties.

One of the most well-known effects of tonal contrast is the flickering flashes of light or of shadow which appear at points of interface when a white grid is placed upon a black ground or a black grid upon a white ground. One has often observed this effect in certain works of Mondrian. As detailed by Wilhelm Fuchs, this sort of effect becomes prominent when the eye stares at the grid itself and is erased when the eye stares at the ground (1967; 101). Furthermore, when white areas are juxtaposed with black areas, but in a progressive succession of grays, they create a vectorial movement which evokes the rotundity of volume.

Another important visual movement apropos black and white is the production of colored after-effects, stemming from the phenomenon of retinal fatigue at the time of the perception of numerous black and white elements contrasted on one and the same surface.

The simultaneous tonal contrast which enriches white, gray and black to a degree of clarity or shadow antagonistic to that of the adjacent region will tend in the same way to render the different regions of color lighter or darker; and this effect can be felt throughout the ground of a spatial field if the field is homogenous.

Moreover, the juxtaposition of white or black to colored regions produces a variety of different effects. White applied in close proximity to another color heightens its intensity, in removing from this color all the white that it can contain in a latent manner. Similarly, in receiving the complementary of this color, it will reinforce the chromaticity of this film of color. However, the tonal contrast existing between the color of contrast and the white, necessarily less dark, will overlay this color with a darker film which can diminish its quality of saturation.

In a similar way, a black area neighboring another color also diminishes its dark tonality and strengthens its chromatic intensity. It will also recover the film of the complementary with a greater luminosity and a lesser quantity of black in its composition. All these interactions vary according to the dimension of regions, their reciprocal positions, the quality of their boundaries, the intensity of their colors and of blacks/whites, and the nature of the surrounding chromatic milieu.

2.3.5.Successive chromatic and tonal contrasts

One must not confuse simultaneous contrasts of tonality and of color which are effected even on separate and distant regions in the visual field with the successive contrasts of tonality and of color. The first only transform the tonal degree or the quality/quantity of color in the two regions considered. The successive contrasts cause more than a tonal and chromatic modification; they result in a configuration/contour of a dimension analogous to that of the initial region, thus producing a ‘virtual form’.

Thus, when the eye, having looked at one or several colored regions over a certain length of time and produced numerous simultaneous contrasts, turns its gaze toward another region of the field, it will project on this region an image or configuration having the contour of the first region, but endowed with a complementary color or a tonal antagonism. It produces, therefore, a complementary successive image, an after-image, possessing a shape and a dimension analogous to the first percept but endowed with a chromatic and tonal contrast. This image, circumscribed in a given shape which is superimposed on a new region possessing its own contours, introduces a very considerable degree of complexity in this new region by virtue of the disparity between the dimensions, color, tonality, texture, of the region focused on and the superimposed film.

Similarly, when dark forms are vividly disclosed on a light ground, an after-effect will project an analogous light-form on a neighboring ground and vice versa.

The successive tonal contrasts will also change the dimension of forms or of regions, since a dark object, or a darker one, will appear smaller than a light object of the same size. As for chromatic successive contrasts, these will institute continuous transformations in the chroma, the saturation, the luminosity, the dimension, and the position-in-depth of perceived elements, multiplying the interrelations among elements already perceived and elements newly perceived, and changing the structures of organization of the visual field that they progressively constitute. Successive images have a dimension which varies with the distance taken in relation to the visual field. They disappear with time, like simultaneous contrasts, but can, like these, be summoned again or reanimated after a blinking of the eyes, a slight movement of the eye, or by the new percept caused by a change of luminosity in the visual field.

The interaction between the successive image and the new region viewed is called a mixed contrast. It is produced when the eye perceives in the new region of focus a mixture between the new color and the complementary of the first region, carried by the successive image.

There still exists a very large number of other tonal and chromatic transformations which are carried out in the perceptual process. Although their effects are constant, and a point of consensus among numerous observers, these transformations are still set under the rubric of “accidental images,” as called by Buffon, who was the first to observe them. These include, for instance, chromatic modifications and projections resulting from a too-strong vibration, or luminous bursts in the visual field, characterized sometimes as “aggressions” of the eye, although the recurrence of these soon render them normal and innocuous, if not banal. They have been the object of particular preoccupation at the center of the Op Art movement, producing tonal and chromatic simultaneous superimpositions in the ‘moiré’ effect, the emergence of chromaticisms from white and black regions, and so on.

The expression ‘colors of memory’ designates those colors “perceived” by reference to a known and remembered tint, foreign to or nonexistent in the actual context. Any prolonged observation of an enlarged visual field may produce these colors of memory, since each color perceived can be transformed by the memory of colors previously perceived. We do not class them in terms of plastic variables since they do not correspond to a material correlative of a specific perceptual activity in a present situation, but rather in terms of perceptual variables. When projected on the visual field, these colors derived from memory are subjected to the law of successive and simultaneous contrasts.

The law of simultaneous or successive contrasts explains those transformations undergone by the field of visual representation, when a given epoch or certain artists break with the habitual use of certain colors, enlarging or restricting the number of colors actually used. These artists disrupt the visual field, not only by incorporating a new tint, but also by modifying all the dynamics of complementary transformations to which the eyes of spectators were accustomed. When Titian uses only four colors, Rubens seven and Mondrian three, the whole system of chromatic mobility is radically transformed, in as sure a manner as when El Greco uses purple as the complementary of yellow or the impressionists and neoimpressionists eliminate black from shadows.

Already the presentation of the law of contrasts as based on a relation of two terms, instead of on a real interrelation of one term with all those which surround it, has appeared as a lacuna to Gestalt psychology. As early as 1925, Max Wertheimer explained: “. . . the experiences show, for example, that when I see two colors, the sensations that I have are determined by the global conditions of all the situation of the stimulus,” and not by two limited regions in the visual field. He was led to conclude that the experience required, among other things, “that traditional theory of visual contrast be replaced by a theory which took into account the conditions of the whole and its parts” (1925; 5).

The research of Albers added numerous elements to the law of simultaneous and successive contrasts by connecting the modifications of color to the form which they circumscribe, to their quantity and position, to the number of times they appear, and to saturation and luminosity. He emphasized the importance of the articulation of frontiers, that is, the nature of the boundaries which separate or connect different regions of colors. Similarly, he linked this phenomenon to the quality of the ground in which a color appears: “Any background subtracts its own nuance from the colors it bears” (1963; 41), modifying, therefore, with the chromatic and tonal intensity of the two regions, the nature of their complementaries. Albers also described the presence of inverted simultaneous contrasts where, in the place of the complement, in certain circumstances, it is the first color itself which is projected on a neighboring surface.

2.3.6.Optical mixture

Chromatic perception is modified still further by the phenomenon of an optical mixture which occurs when two juxtaposed tints, perceived at a certain distance, produce in the eye a third color, called the resultant color. In a certain way, the specific action of these two first colors is annulled, rendered imperceptible or even invisible, to the benefit of the third color. As opposed to the color which results from a mixture of colored pigments themselves, this third color—obtained by way of an optical mixture—retains all its luminosity. These resultant colors are produced even more when the first contrasting tints are present in equally small quantities.

Another source of chromatic movement stems from the phenomenon of adaptation of colors among themselves. Thus, a blot of intense red will bring out the red components in the surrounding colors. This adaptation is a consequence of simultaneous contrast, because the projection of the green complementary in a neighboring region reactivates, at the same time, the anticomplement red which is contained in this same region.

Another type of transformation occurs in the case of the color conveyed in a watery medium or transparent fluid. Instead of offering color a stable color surface like, say, oil, gouache or pastel would, it presents a volumetric color. In other words, the color undergoes transformations pertaining to its very position in the volume or the type of envelopment presented by the fluid volume. As Albers said: “In practice, the majority of watercolors have volumetric colors: several layers superimposed augment their dark character, their weight and chromatic intensity” (1963; 13).

2.4.Texture

Texture is a property of material bodies primarily apprehended by the sense of touch, evaluating what is hard or soft, rugged or smooth, penetrable or not penetrable, continued or discontinued, and so on. All tactile percepts are gathered, compared and contrasted, and interrelated in an organic space capable of unifying their extreme diversity.

But the intimate connections established by experience between what is touched and what is seen at the same moment tend to blur for common knowledge many distinctive traits of these two universes of perception.

In visual semiotics, we understand by the term ‘texture’ a plastic variable designating a property of colored matter in its innermost depths as well as on its surface, whereby it presents various inclinations and disjunctions which modulate in different ways the absorption and refraction of luminous rays on opaque bodies, thus modifying their chromatic effects. As interpreted in terms of vision, texture will also be instrumental in the construction of distance appreciation and depth effects.

Like the term ‘color’, the term ‘texture’ is a plural term, since the diversities of texture are countless, constructed as they are at several levels of the visual work. In the first place, the microstructure, or the grain of the surface on which the perception of the color is realized, always corresponds to a particular type of discontinuity in the retinal stimulation whether it concerns wood, canvas, glass, or paper: “Because a color has been spread out on a certain surface, it is going to take on a particular aspect” (Guillot, 1957a; 81). This determinism is not uniquely psychophysiological, but is based on an objective property of the support of the visual work. This particularity can be masked, accentuated, or transformed by the composition of pigments and the manner in which they are physically spread out. But it will always produce ways in which color appears that modify the chroma of the pigment and consequently change the spatial organization of the global perceptual field.

Because the texture of the support can be masked superficially by a certain way in which the pigment is spread out, Chevreul failed to recognize its crucial importance in painting, whereas he pointed out the major role played by the cruciform pattern in the woven threads with which tapestry is always faced (192, par. 874). But more recent studies have pointed out that, when the colored surface is not anchored in an underlying level of cyclical or alternating variations, it has the tendency to become more mobile and unstable in its localization, taking what has been called “the diaphanous aspect of color in expansion” (Kanizsa, 1957; 108).

The effect of texture is also produced by both the internal structure of a pigment and by the manner in which it is spread. The study of materials which visual artists use in the course of creating artworks is relatively recent. In fact, as explained by Rabati: “it is only from the end of the 18th century that progress in chemistry has allowed us to pursue a rational study of the principal constituents (suspension mediums and pigments) of preparations, of which the processes of elaboration were, up until then, jealously guarded” (1957; 155).

The same pigment can, in effect, modify its chroma in space and time, according to its stability and the nature of its internal pulverization. This, moreover, defines its proper texture.

Following the pulverization of a pigment, in a more-or-less fine way, its color will change . . . at first in proportion to the product becoming more refined, the surface is augmented. When the grains are large, we have the impression of a very colored object; when the grains are small, there are many reflecting surfaces, the powder reflects a lot of white light and it appears clearer. (Guillot, 1957a; 169)

Similarly, the technique of spreading out, of dilution, of superimposition of layers of pigment, can make the same color vary: “The way of spreading the pigment and of mixing it with other colors considerably influences the optic properties of the color ‘really’ obtained” (Guillot; 174).

Marcel Guillot pointed out also that the pigments used by painters, “even finely pulverized . . . remain very strongly colored” (169). In other words, they participate, through and through, in the chromatic property that they convey.

The effects of glazes, which have been sought by traditional painting, present particular chromatic effects, because of the specific superimpositions of diluted pigments in different mediums of suspension, acting therefore at varying levels of texture: “A glaze formed by a white pigment diluted in turpentine, spread in a thin layer on a black ground, gives a bluish grey because the black panel does not reflect light diffused laterally” (172). However, on a white ground it will produce an orangish grey.

The differences in texture produced by different brushstrokes, or the manner in which pigment is spread, from discontinuous stippling to greasy and smooth beaches more or less marked out in relief, are better known today because of the American Action Painting or the Quebec Automatism artistic movements. Let us recall, in this regard, the impact of the types of boundaries of a mass on certain effects of texture. As expressed by G. Kanizsa, when the contour of a mass is neat following a sudden change in type of stimulation, its color appears as dense and intense, but when the contour or boundary is more indefinite, following a gradual change in the type of stimulation, the chromatic mass becomes diffuse, dusty, and as though covered with a veil of smoke (Kanizsa, 1957; 110-111). This purely optical textural effect is far from being unique, since any modification in the continuity of a given texture will produce, at the same time, different colors, forms, vectorialities, dimensions, and positions in depth.

Produced by a variety of techniques, such as thickening or thinning of the layers of pigment, the seedlings of blots in variable reliefs and the introduction of materials underneath or into the pigment, the variations in texture seem to directly indicate a privileged contact with matter. But texture, like color, does not adequately inform us of the nature of the material of which an object is made. In the general experience of reality, as well as in the domain of visual language, it is through repeated and accumulated experiences of concrete manipulations of objects that we learn to link certain textures to certain materials. It was on the basis of many common misapprehensions that Duchamp, who opposed the notion of visual perception as a purely retinal reading, with a grand sense of irony filled an iron cage with small blocks of marble resembling cubes of sugar. Indeed, a similar texture can refer to different materials: sugar is lighter than marble, melts in water, possesses another flavor, and so on.

The general reference to an illusion of matter, so commonly attributed to texture in visual works, can mask one of its most important properties, which is the fact that it is an essential component of visual language. Whatever its reference to tactile space, texture can only be recognized in visual representations by way of the organ of sight. In painting and most often in sculpture or architecture, texture is perceived not by the hands or the cutaneous surfaces of the body, but by the eye. Moreover, the research of J. J. Gibson (1966) has shown the unique contribution that variations in texture make to the visual apprehension of distances in depth. This visual variable thus affirms the potentiality of visual language to make reference to nonvisual spaces, that may be in fact not only tactile but also postural, kinesthetic, etc. In other words, visual semiotics has to be concerned with any further information that cognitive sciences may offer about the many sensory spaces which are elaborated through experiences of reality. Though they do not have their point of origin in visibility, they may be represented and organized by the spatial quality of visual representation.

The definite distinction between textures belonging to the very structure of visual components and those which are only referred to should help us to be aware of the specific interrelations between tactile and visual spaces. The figurative type of painting has widely developed the fictional possibilities of the representation of tactile experiences by the production of pictorial textures dissociated from those of their reference. Often, a relatively smooth surface will afford, by a play of tonalities, illuminations, and a sliding effect between forms and colors, the illusion of uneven, chaotic, and shaggy textures. These could refer to briars and shrubbery, velvets or sequins, rocky grounds, tempestuous seas, etc.

A type of treatment of pictorial pigment which creates these illusions of texture is not any more “concrete” than another which presents its proper texture as an object of perception. A wood table, represented in a pictorial work, is not made of wood; and the leaves of trees do not incorporate the components of leaves in external reality. Any material body possesses a texture as well as a color, and both, put into visual language, are capable of connoting an object or an experience stored in our memory. This is what made Noel Mouloud say, in his La Peinture et l’espace: “An ‘informal’ art knows very well, by the processes which speak directly to vision, to evoke this contact with matter” (1964; 94).

Instead of referring to verbalized objects which belong to the external world and which as referents are often ambiguous or polysemic, numerous contemporary artistic movements have been led to use the textural characteristics of the matter itself, which are the very components of visual language. Far from being nonreferential, this form of representation refers precisely to experiences of reality where the dynamisms of hardness, softness, penetrability, elasticity, smoothness, glossiness, pastiness, sharpness, and so on, have been known and experimented with widely. Instead of abstractly referring to illusory ‘objects’ by mimetic suggestions, these forms of representation solicit concrete experiences pertaining to the materiality itself of the organized elements in the visual field. The dynamics of concrete experience, based on memorized experiences, become an organized part of an awareness, instead of remaining isolated elements, dispersed in the heterogeneous sensory-affective spaces.

2.5.Perceptual Variables

In addition to the plastic visual variables, color and texture, there exists another group of constant stimuli which form part of the coloreme, that is, this correlative region of a centration in the visual field. If plastic variables are perceived almost directly, the variables called ‘perceptual’ are the more complex products of endogenous mechanisms of perception acting on external stimuli. These are: dimension, position in the plane, vectoriality, and the boundaries/contours which will produce the regroupings called ‘forms’.

2.6.Dimension or Quantity

Quantity corresponds to an essential characteristic of any expanse of matter reflecting luminous rays. The quantity (or dimensions, or size) of material observed in a centration presents itself as a mass or an elastic solid possessing three dimensions (thickness, height and width) even if they cannot be metrically measured.

In this context, the notion of mass refers to the ‘quantum’ of material energies distributed in an expanse of matter forming various aggregates in the visual field. If one would make an analogy with the notion of mass as used in physics, one would say that, in the visual field, mass is defined as the quotient of resistance of its own energies in their interaction with the energies of the ambient field which act upon it, imposing a certain number of tensions, changes and visual movements. This quantity or topological mass is always endowed with an internal volume, as explained above, characterized by an axiality, a vectoriality, and a given expansion.

The dimension or quantity of a given aggregate is a major factor in the transformations which elements undergo in the visual field. As we have seen, a color of too-small dimension cannot be assured of its chromaticity and is transformed according to an optical mixture. On the other hand, a much more extended color is transformed differently by way of the chromatic effects of the complementarity which plays upon it and adjacent colors.

Each of the other visual variables at the heart of a coloreme is subjected to a variation, according to its quantity, which transforms the equilibrium of internal energies and “brings closer” the region to the perceptor. Albers has already commented on this in the case of color: “An augmentation in the quantity of a color—independently of the dimension of the format—will reduce visually the distance” (1963; 13) between this color plane and the spectator, thus producing an effect of proximity and intimacy. This same movement toward the front can be produced as much in a partial region as in the global visual field. This expanding in the dimension can be achieved within a continuous element, or by the regrouping of several discontinuous elements, under a certain form of neighboring.

In a coloreme, the evaluation of the dimension of its various components can be made by a comparison with its internal elements or in relation to the components of neighboring coloremes. However, the determination of the dimension, at this level, depends upon measuring instruments used, as well as upon the dimension of other objects, large or small, with which an object is compared. Also, the scale of appreciation of the dimensions of a coloreme will differ from that used in a larger region or in a global work. However, it must remain proportional in these diverse regions using an internal system of gradients of dimension based on the coloreme being multiplied a certain number of times.

This proportional scale evaluates the number of times that a coloreme can enter into the surface/volume of another region. This scale is topological and nonmetric, since it takes into account the effect of expansion which an element undergoes, through chromatic or tonal simultaneous/ successive contrasts.

2.7.Implantation or Position in the Plane

This perceptual variable corresponds to the relative position of groups of coloremes in relation to the three dimensions (height, width and depth) in the specific field under consideration. This position is determined by two series of parameters. The first concerns the relations of distances with regard to the external peripheral sides, defining the visual field, and the second, the internal relations of these elements accentuated or not by the energies of the infrastructure of the Basic Plane. This system, which constitutes a syntactic structure of visual language, will be described more fully at a later point. We will devote ourselves here to describing the characteristics of the third dimension, depth. It is necessary to specify at the outset that this notion of depth does not refer to simple relief or that physical condition, resulting from textures and corresponding to the effects of elevation or of lowering of pigment in relation to a level surface, which represents the support of the visual work. It is rather a third dimension constructed as an inherent element of space by the perceptual processes themselves.

There exist two modes of spatial depth in the syntax of visual language: optical depth and illusory depth. Any positioning of visual stimuli, at one point or another of these different categories of depths, modifies some of the visual variables which compose them: chroma, dimension, tonality, texture, and so on. This is why, even if it is a product of the perceptual synthesis, the position in depth in the plane constitutes an essential characteristic of the basic visual unit, that is, an actual visual variable.

2.7.1.Optical depth

Optical depth is that which is produced by the proper interrelation between colored elements, to which are added the influence of textures or of degrees of distinctiveness of contours, which will cause a given zone to move forward or to recede in relation to another in the visual field. But it is primarily by their very chromatic quality that coloremes and groups of coloremes will acquire different positions in spatial depth.

In a general way, the tradition has stated that red zones were to advance, blue zones recede, and yellows be situated between the two. However, as we have already pointed out, hundreds of nuances of primary colors exist. Those which are truly put in action in a visual field, being transformed by other variables, such as tonality, vectoriality, dimension, or texture, may behave quite differently without contradicting the law of universal movement of visual elements toward the front or rear.

This optical depth has often been commented on by producing artists. Thus, the constructivist artist El Lissitsky wrote: “New optic discoveries have taught us that two regions of different intensities, even when they rest on a plane, are seized by the mind as being at different distances from the eye . . . In this space, distances are uniquely measured by the intensity and the position of strictly defined regions of colors” (1968; 354).

The French artist A. Herbin described the same phenomenon differently:

Painting has no need for a third dimension, neither in reality nor by whatever artifice, because color manifested in an expanse of two dimensions, possesses in itself a spatial power. Certain colors express space in depth (blues), others space in front (reds). Certain colors express radiance from within to outside (yellows), others from the outside, within (blues). (1949; 94)

The positions of colors in depth vary not only with the structure of the other visual variables that they convey, but also with the environment in which they are inserted and which acts, in its turn, on the visual variables constituting the chromatic element. As expressed by J. Itten:

When six tints, yellow, orange, red, violet, blue and green, are juxtaposed, without intervals, on a black ground, the luminous yellow appears to advance distinctly into the foreground while the violet recedes in depth in the dark ground. The other tints take an intermediary position between the yellow and the violet. A white background will modify the effect of depth. Violet seems to advance far from the white ground which retains the yellow with its close luminosity. (1970; 77)

When orange is interposed in the distance in depth separating yellow and red, the distance between yellow and orange is proportionally inferior to that which separates yellow from red. The same happens with the distance which extends from yellow to red/orange and from red/orange to blue, whereas the intervals between yellow and green and green and blue are proportionately larger.

A more luminous tint on a dark ground will advance in proportion to its luminous intensity and will recede in the same way on a clear ground. When tints of equal luminosity seem lighter or darker, the light tint seems to advance and the dark one to recede.

Contrasts of saturation between two shades produce another effect of depth. The more saturated tint advances, the less saturated one recedes. But if they are of the same saturation and luminosity, the contrast of the clear and the dark will produce a contrary effect.

Certain intervals in depth between two colors can be so distant that they produce an effect of rupture between two regions, as if separated by a void or a nonenergized space. When a single element seems to be at a too-distant interval in the forefront in relation to an ensemble, it is said that it “floats” in front of the pictorial plane. Similarly, an element which recedes too suddenly and too far into the rear produces a hole, a void, a spatial discontinuity that perception cannot compensate for to maintain a pictorial unity.

Albers studied the production of depth that he called the illusion of space, created by the qualities of neater frontiers/contours which lend to various crisscrossing stripes nearer the periphery of the canvas an over-under effect. In other regions of the work this effect would be reversed or annulled. Albers confirmed the findings of Gestalt psychology to the effect that, when two similar forms are situated one above the other, they will assume a different position in the depth of the field. In a general way, moreover, Albers proposed that any quantitative increases in saturation and dimension of a color cause it to appear closer to an observer. The majority of his experiments were devoted, however, to the topological relations of neighboring/proximity, or separation/distancing, produced by distinct or indistinct frontiers. He experimented with the possibility of obtaining changes in the luminous intensities of adjacent colors, and the resulting disappearance of frontiers, which in themselves accentuate the interpenetration of one color upon another, at the same level of depth.

Albers reappropriated the fundamental notions of the “push and pull” proposed by Hofmann and its undulatory movement within the pictorial mass as well as the variations in the harmonics when changes are introduced in illumination, direction, and the sequence of the reading of a series of regions.

The theoretical teaching of Hofmann had pointed out, in the movement of ‘push and pull’, the fact that the pictorial plane reacts “automatically” in a direction opposite to and with an equal force to any visual stimulus which it receives. Thus, any plastic element which, by its own dynamism, positions itself at the front of the pictorial plane, pushes neighboring elements toward the back and vice versa. Specifically, Hofmann defined color as the plastic means of creating “intervals,” that is, energetic regions interrelating quite distant areas through the harmonics of color. This harmonics, therefore, designates those tensions existing between colors that are situated at various distances in the three dimensions of the visual field: “Swinging and pulsating form and its counterpart, resonating space, originate in color intervals. In a color interval, the finest differentiations of color function as powerful contrasts. A color interval is comparable to the tension created by a form relation” (Hofmann, 1948; 67).

Several hypotheses have been offered for the movement of colors in depth in the visual field, linked most often to the structure of the visual apparatus. In Vision in Motion (1947), L. Moholy-Nagy wrote: “The lens of the eye does not stare at various colors in the same way. Red thickens the lens and renders the eye farsighted; this transformation gives red a closer position than blue which flattens the lens and renders the eye myopic.”

A decade later, a scholar, Marcel Guillot, made a case for the variation in the degree of contraction which the crystalline lens of the eye must effectuate to establish focal distance, that is, a point where luminous rays gather together:

We know that this distance is not the same for different colors. The result is that it must be accommodated in a different manner if it concerns blue or red. When the distance is of ten meters, you must make an effort, when it is three you must make another. If two objects are at the same distance, one blue, the other red, you feel, in an instinctive way, that you have accommodated in passing from one to the other, as if one of the objects was close and the other far, whereas the distance is the same in the two cases and that it is the color which is not the same . . . There is an effort of accommodation for the various colors and because of this there must exist a space of colors. (1957b; 151)

But he also noted that if, in general, reds advance and blues recede, artists may wish to impress them with different positions and do this by other procedures, such as playing on values and contours.

We can place among the phenomena deriving from the perceptual variable of position in depth the effects of transparency. These result from the perceptual estimation of a superimposition of two colors or two tonalities, whereas one of the tints appears as situated below, that is, behind the other color. An analagous effect of transparency is produced in the perception of a composed color or of a color subjected to the effect of equalization or complementarity. The different energetic vibrations of these various wavelengths produce stimuli which are estimated as more behind and more in front in relation to others in the same colored mass.

In the same way that it is not possible to fix in immutable definitions the characteristics of such and such a color, it is impossible to define a priori the position in depth that a color can occupy. Not only do these characteristics change according to the field or the perceptual context, but the trajectories of perception can modify already perceived characteristics, thereby producing particular visual movements and transformations in the interrelations between regions. We will call ‘optical perspective’ the ensemble of the network of depths defined in the visual field by the unique dynamisms of colors and tonalities and the spatial organizations so derived.

2.7.2.Illusory depth

Illusory depth is a perceptual phenomenon which does not result from the dynamics of the visual variables as such. But it is realized through the adoption of a system of conventions, adding to perceptual mechanisms the impact of logical and conceptual knowledge, in order to produce the illusion of very great depths in the visual field of representation.

This illusory depth is the product of a combination of often quite imaginary points of view, in that they are not often realizable in concrete experience. They are codified, in various cultures, according to almost two dozen perspectivist systems. The complexity and the diversity of these systems and of the norms of representation they require qualify them as syntactic modes of approach to experience which are the object of a description below, as parts of the syntax of visual language. We note only that any illusory mode of hollowing far distances in the visual representation remains dependent on the dynamics of the optical perspective which creates a topological shallow depth. These two types of perspectives can enter easily into conflict within the dialectics of visual propositions.

2.8.Thermal Values

The vocabulary of the artist’s studio has often linked the positioning or effect of movement in depth of chromatic elements to their thermal value: warmth and coldness. Warm colors advance, cold colors recede. Clear tones are interpreted as warm and neighboring colors of blue as cold. But the thermal estimations vary most often with the perceivers and the producing artists, as a result of associations stemming from the mnemonic repertory of each, in connection with nature or cultural facts. These thermal evaluations do not correspond to any reality of the spectrum’s luminous rays. The energy of the photons, for example, which produce a wavelength corresponding to red, is much less than that of the photons which produce blue. (Boll, 1962; 25).

The perceptual estimation of a given color as warm or cold refers undoubtedly to the experience of organic thermic space as well as to an aspect of tactile space, both closely linked in this matter, but conditioned more by external causalities than by properties of chromas. Lived experience teaches that material surfaces are literally heated, to variable degrees, by radiant energies of natural light. In this regard, a black surface which absorbs the majority of rays of light can, when it is exposed to light, become literally warmer than a white surface. But this effect is less notable with other surfaces of color, opening the door to a wide variety of estimations. By association, visual perception may connect contradictory characteristics to colors if observed in different contexts. Indeed, green-blues and blacks are, at times, considered as cold colors, and yellows, reds and whites as warm colors, when associated with the sun’s radiance.

Kandinsky, who believed it necessary to use, in large measure, the thermal properties of chromas in his theory of color, did not fail to recognize that “any color, without a doubt, can be at once warm and cold” (1977; 70, note 1). Albers corroborated this ambiguous status of color in his own teaching. Although blue seems cold and the yellow/orange/red group seems warm in occidental tradition, “there also exist warm blues and cold reds at the interior of their own nuances.” He also added that “if we mix white, black or grey with these colors, personal interpretations of temperatures risk rapid divergence” (1963; 59).

All these contradictory testimonials have persuaded us not to retain the notions of warm and cold as actually operative among the characteristics of colors, although assuredly such associations on the part of a perceiver will determine many dynamic qualities and movements of the chromatic region to which they are attached. But it is only a question here of a connotation and not of a constant and internal character attached to perceptual mechanisms.

2.8.1.Gravitational values

It is a similar case for the notion of weight which various tints seem to possess, the darker appearing heavier, or more subjected to a gravitational attraction. This movement toward the bottom or the top in the pictorial field, in our view, is not linked to color itself but rather to the position of plastic elements in the field of autonomous forces which construct the Basic Plane. This is exemplified by the various forms mentioned by Kandinsky which, while remaining the same, do not have the same weight when they are placed in the top left corner or in the lower right corner of the canvas. Whereas it has been traditionally recognized that the darkest color in the pictorial field, the one containing the most black and the least white, was the heaviest visually, an experiment of Albers demonstrated that the perception of the quantity of black or white that a color contains, a relatively simple operation it would seem, could not be made by more than two thirds of his advanced students (1963; 33).

There has also been a belief in the ability to reach an objectivity in this respect by recourse to photography, but this position ignores the fact that the recording of lightness or darkness on the retina differs from the sensitivity of photographic film. In white and black, this film yields a lighter white and darker blacks than the eye perceives. In the same way, color photography cannot provide us with information about the perception by the eye, because it deviates even more than does black and white photography, overestimating the luminosity and intensity of blues and reds (1963; 34-35).

In the domain of sculpture or architecture, the perception of relative weight and of the resulting equilibria between elements cannot normally be formed directly. Most often, it requires the resort to prior verbal information which would state that a mass is made of bronze, steel, wood, for example. The weight is not perceived by the eye but deduced solely from acquired verbal knowledge. While this perception is a characteristic of tactile and kinesthesic experience, it is not a property, as such, of visual language.

In conclusion, it appears that the antinomies of warm/cold and light/ heavy, which have played so important a role in the presemiotic theory of Kandinsky, are not intrinsic properties of visual variables, but constitute an active source of indirect connotations. In order to take into account the effects of movement and positioning which are sometimes linked in visual representations to these nonvisual aspects of reality, we have kept as a distinctive trait the notions of light and dark about which there seems to be ready consensus.

2.9.Vectoriality

Vectoriality or orientation designates the perceptual variable that indicates the direction in the three dimensions taken by the energetic movement of a coloreme, or a group of coloremes. It is perceived as a directional tension of the visual variables, capable of acquiring a virtual prolongation in the field or of establishing relations with close or distant regions in the visual field.

In contrast to the position in the plane which accounts for the transformation which the visual variables undergo, for the fact of their localization in the visual field, vectoriality corresponds to the inscription of a moving tension in these variables. It is related to Kandinsky’s conception of movement which he defined “as a tension plus a direction” (1975; 91), the term “tension” implying specific forces or energies. The groups of movements or vectorialities at the core of coloremes are interlinked and reverberate, generating virtual movements as well as virtual visual variables. The energetic intensity of vectors depends, in large part, on their mode of insertion in the Basic Plane.

Our substitution of the notion of vectoriality for Bertin’s variable of orientation is quite significant in stressing the difference between graphism constructs and visual language. As well as carrying the topographical components of direction (up, down, oblique, sideward), vectoriality stresses the more important energetic level of behavior of purely visual components. Vectoriality is direction plus force, tension, and energy.

2.10.Boundary or Contour

The boundary variable, also called frontier or contour, corresponds to a qualitative change between two neighboring regions in the visual field, likely to produce open or closed forms. The traditional plastic analysis never considered boundary in itself, but only as a secondary effect in the situation where a synthetic grouping of numerous coloremes could determine what has been called a ‘shape’, that is usually a closed form. The dynamics of the boundary/contour results from the sort of liaison or passage existing between two visually differentiated zones. Boundaries may appear as distinct or diffuse; they are marked by a contour/line or by a graduated change, by an autonomous plane or by a simple juxtaposition of contrasting planes. An extremely graduated transition between two zones does not lead to the presence of a contour/line, but rather to a zone of color or tonality more or less homogeneous in relation to its neighboring regions.

The contours or frontiers do not merely play a primordial role in the ease/difficulty of passages, or the type of communications possible between regions. Like textures, frontiers have a direct effect on the chromatic quality of the region they encompass or on the organizational structure of the surrounding spatial field. When a contour is neat, the internal color presents a solid and dense aspect; as the degree of transition (also called marginal gradient) becomes softer, the color becomes powdered and airy, passing gradually from the aspect of a solid to that of a penetrable volume. With respect to diffuse boundaries or borders: “The most remarkable effect concerns the tissue of the chromatic substance which from being compact, smooth and solid becomes soft, velvety, pasty. It acquires, in addition, a certain density and seems localized in front of the surface which serves as its ground, like a layer of powder or a film of smoke spread over” (Kanizsa, 1957; 110).

Thus, two grey or colored circles, identical except for the distinctiveness of their contour, will be perceived as entirely different from the point of view of color, density, texture, position, and so forth. This transformation in the plastic variables of a region, attributable to the state of its boundaries, is echoed in all of the surrounding spatial field which takes on the same qualities of softness and impreciseness as the zone of blurred contours. Kanizsa explains this phenomenon: “When the contour is distinct (following a sudden change in the type of stimulation), a stable and precise organization is produced; when indefinite (following a gradual change in the type of stimulation), the structure of the field is unstable and these characteristics of spatial organization are related also to the color [of this spatial field]” (Kanizsa; 110).

The “Musatti effect” is the name given to this phenomenon by which the transformation of contours has as its results not only a considerable increase in the equalization among neighboring regions but also a modification of the spatial organization which depends on chromatic qualities: “Grounds lose, in large part, their compact aspect, they become more dissolved, more airy, as if a tenuous layer of mist or a shadow was spread out before them” (Kanizsa; 112). In blurred frontiers, it is very difficult to perceive varied chromatic zones, but when there is a sudden transition between two regions, the chromatic differentiations which accompany it are easily perceptible.

2.10.1.Forms

The variable of boundary/frontiers plays a dominant role in the perceptual constitution of differentiated ensembles known as ‘forms’ or shapes. But it should be remembered that other visual variables, such as color or texture, are just as important causal factors of “forms” as boundary is.

Any form is produced by an intensification or regrouping of visual variables according to topological and gestaltian relations. Resulting from a convergence and an interaction of several visual forces, all forms possess a determinate orientation or vectoriality, that is, a tension oriented toward an angular variation in the three dimensions. Moreover, as figures, they can be defined only by their relation with the environment from which they are differentiated.

2.10.2.Open or closed forms

Considered as a subcategory of the boundary/frontier variable, forms can be divided into two general groups: open forms and closed forms, demarcated or not by a line/contour. Any form whose frontier is constituted by a linear element, demarcated or not, which, after a hypothetical point of departure, returns to itself, is called a ‘closed’ form. This linear element, when it is marked, is called line/contour or, by way of abbreviation, simply contour. When the line/contour cannot be reunited with its point of departure, or when the boundaries of a mass seem almost indistinguishable from its environment, the form is qualified as ‘open’. Linear, textural, chromatic quantifications of masses which reach the peripheral sides which delimit the format of the work (which we call, further on, the Basic Plane) are called ‘open’ forms, provided that the end of the pictorial system is not underscored by an added line/contour. A linear form of contour can also envelop a group of closed or open forms, constituting the ensemble as a closed form.

In the closed form, the movements of the forces which constitute it (or vectors) are more accentuated as the gradient of the curves varies. By contrast, in the open form the movement of the oblique creates the strongest tension, because of the continued reference to the horizontal or vertical axes. In the case of many oblique forms, similarly oriented, their particular tension is accompanied by an oscillation toward the virtually closed good form which can envelop them.

Like a figure on more open ground, a closed form will see its internal volume amplified by associations with known external objects describable by both closure of forms and tridimensionality.

A form called linear or unidirectional, which is somewhat extended in the two dimensions of width and height, acquires at the same time a characteristic of surface and of mass, endowed with a three-dimensional internal volume.

2.10.3.Actual and virtual forms

From their vectorialities, both those of their components and those which characterize their global gestalt, forms constructed by visual variables actually materialized in the visual field produce nonmaterialized ‘virtual’ forms expanding their own energies. In the same way, the masses, as open or closed volumes, can be virtual or actual, and any virtual prolongation of opened, linear and bidirectional elements produces an open virtual mass. Virtual forms, like actual forms, are proportionately more dynamic as they are better integrated in the axial energies of the Basic Plane or its formative sides.

In closed forms, which are always closed volumes, vectorialities can produce actual or virtual movements. Thus, symmetrical polygons (squares, circles, regular stars, and so on) possess a tendency toward peripheral rotations around their central axis. However, most frequently, perceptual mechanisms accentuate to a greater extent their movement along the horizontal axis. This horizontal, lateral movement will go toward the right or the left depending on whether one or the other of the frontiers is more or less ‘rigid’ or closed. Rectangles or triangles in which the height is greater than the width will undergo a movement along the vertical axis (Arnheim, 1954; 402).

Inversely, any closed forms which can make a rotation along a central axis, whether horizontal, vertical or diagonal, possess a quality of symmetry. In the same way, any form of which a section of the frontier is a right line is capable of making a rotation on this element-hinge and of producing a virtual, symmetric volumetric form.

Any symmetrical form produces a particular visual movement which subdivides it into two parts, thus producing an oscillation between its gestaltian unity and the vectorialities of its parts.

Furthermore, any asymmetry is interpreted in its energetic relation to a potential symmetry. One of the most common pictorial themes, the representation of the human face, is made dynamic by the tension established between the two sides of the face, which are always asymmetric, in contrast to the two ‘good forms’ produced by the symmetric rotation of the right side on the left or the left side on the right.

All open, unidirectional or polydirectional forms are prolonged in the neighboring visual field according to their vectorial orientation. By their regrouping, open forms produce actual internal volumes; by their prolongation, virtual internal volumes. Similarly, the regrouping of closed forms produces virtual internal volumes.

2.11.Repertory of Forms

The semiotic description must, at the level of the basic element as at the syntactic level, be able to account for movements and interactions which dynamically intervene in the forms or in the superregions produced by visual discourse.

Given the deficiencies of existing repertoires of forms (Barrett, 1983), which exclude open as well as virtual forms, both of which are fundamental components of visual language, we have developed a system of classification of forms which is presented in Appendix II.