In his seminal essay, Critique of the Image, the renowned semiotician, Umberto Eco, proposes a clear taxonomy of codes used to interpret an image in the semiotic tradition. He differentiates between the following types of codes (the text below closely follows Eco’s original formulations) :
1) Perceptive codes, which for Eco are establishing the conditions for effective perception and are studied within the psychology of perception;
2) Codes of recognition, uniting blocks of signifieds into semes, according to which we recognize objects. These codes are studied within psychology of intelligence, memory, learning or within cultural anthropology;
3) Codes of transmission, constructing conditions for the perception of images. Eco uses an example of the dots in a newspaper photograph or lines in a TV image. These could be studied by the information theory physics;
4) Tonal codes, related to the way the message is transmitted (‘expressionistic’, ‘forte’, ‘piano’, ‘crescendo’, terms used in musical notation);
5) Iconic codes, usually based on perceived elements actualized according to the codes of transmission. These can be articulated into figures, signs and semes.
(a) Figures, or conditions of perception (subject – background relationships, light contrast, geometrical values), transcribed into graphic signs.
(b) Signs, denoting (i) semes of recognition (nose, eye, sky, cloud) by conventional graphic means; or (ii) ‘abstract models’, symbols, conceptual diagrams of the object (the sun as a circle with radiating lines).
(c) Semes, more commonly known as ‘images’ or ‘iconic signs’ (a man, a horse), formulating a complex iconic phrase.
Iconic codes shift easily within the same cultural model or even the same work of art.
6) Iconographic codes, elevating the ‘signified’ of the iconic codes to the status of a ‘signifier’ to connote more complex and culturalised semes: ‘Pegasus’, ‘Venus’, ‘King Priam’.
7) Codes of taste and sensibility, which establish the connotations provoked by semes of the preceding codes. Thus a Greek temple could connote ‘harmonious beauty’, as well as ‘antiquity’.
8) Rhetorical codes are borne of conventionalisation of as yet unuttered iconic solutions, assimilated by society to become models or norms of communication. These could be divided into rhetorical figures, premises and arguments.
(a) visual rhetorical figures are reducible to verbal visualised forms. Examples are a metaphor, metonymy, litotes, amplification and so on.
(b) visual rhetorical premises are iconographic semes, bearing particular emotive or taste connotations. An image of a man walking along a never-ending tree-lined road connotes ‘loneliness’.
(c) visual rhetorical arguments are true syntagmatic concatenations imbued with argumentative capacity, for example in the course of film editing, succession/opposition between different frames communicates complex assertions.
9) Stylistic codes are determinate original solutions either codified by rhetoric, or actualized once. They connote the type of stylistic success, the mark of an ‘auteur’.
10) Codes of the unconscious. By convention they are held to be ca pable of permitting certain identificationsor projections, of stimulating given reactions, and of expressing psychological situations. They are used particularly inpersuasive media.
Umberto Eco is an incredible polymath, his works are a total joy to read. His final magnum opus, a series of books on art bringing together all his immense semiotic knowledge and accompanied by fabulous illustrations includes such gems as ‘On Beauty’ (2004), ‘Infinity of Lists’, and ‘The Book of Legendary Lands’.
Eco, U. (1982) Critique of the Image, in Burgin, V., ed. Thinking Photography, MacMillan,
Eco, U. (2004) On Beauty, Secker and Warburg
Eco, U. (2009) Infinity of Lists, McLehose Press
Eco, U. (2013) The Book of Legendary Lands, McLehose Press