from Camera lucida: Reflections on photography
[Barthes 1981] Roland Barthes. Camera lucida: Reflections on photography;
1st American edition, Hill and Wang, ISBN: 0809033402.
[about Barthes, see http://en.wikipedia.org/wiki/Roland_Barthes]

“A specific photograph, in effect, is never distinguished from its referent (from what it represents), or at least it is not immediately or generally distinguished from its referent (as is the case for every other image, encumbered--from the start, and because of its status--by the way in which the object is simulated): it is not possible to perceive the photographic signifier (certain professionals do so), but it requires a secondary action of knowledge or of reflection. By nature, the Photograph (for convenience sake let us accept this universal, which for the moment refers only to the tireless repetition of contingency) has something tautological about it: a pipe, here, is always and intractable a pipe. It is as if the Photograph always carries its referent with itself, both affected by the same amorous or funereal immobility, at the very heart of the moving world; they are glued together, limb by limb, like the condemned man and the corpse in certain tortures; or even like those pairs of fish (sharks, I think, according to Michelet) which navigate in convoy, as though united by an eternal coitus. The photograph belongs to that class of laminated objects whose two leaves cannot be separated without destroying them both: the windowpane and the landscape, and why not: Good and Evil, desire and its object: dualities we can conceive but not perceive...” p5,6

[more “Camera Lucida” discussion within Rose, Gillian, Visual Methodologies. ]

"The referent is there in photographic images in ways that it is not in other sorts of visual imagery, Barthes argues. As a result, he suggests that photographs can be interpreted in two ways. First, there is the level of the studium, which is a culturally informed reading of the image, one that interprets the signs of the photographs. But he says that some photographs produce a different response, which is a second kind of reading, by containing what he called a punctum. A punctum is unintentional and ungeneralizable; it is a sensitive point in an image which pricks, bruises, disturbs a particular viewer of the their usual viewing habits. He went so far as to suggest that ‘while the studium is ultimately always coded, the punctum is not.’ That is, there are some points in some photographs that escape signifiers and shock the viewer with their ‘intractable reality.’”

[Don't worry if some of this language seem strange--we will be discussing many of these terms in the semiotic lecture]