Semiotics.

Semiotics originates from the study of signs, these signs could be held in Photographs, Drawings or paintings, but also include words, sounds and body language.
The word "semiology" originates from the Greek word "Semion" meaning sign.
Ferdinand Saussure is renowned for developing semiotics, but to follow in his footsteps and further developed the theory are: American philosopher Charles Saunders and Charles William Morris. Then leading modern semiotic theorists: Roland Barthes, Algridas Greimas, Yuri Lotman and Julia Kristera.
Roland Barthes work and research meant that semiotics became a major approach to cultural studies in the late 1960's. For Saussure, who studied as a linguistic, semiology was 'a science which studied the roles of signs as part of social life.'
Semiotics looked at the 'reality' of an image, looking at how the meanings are made, and what connection they have to the real world.
However, even with the most basic images and semiotic terms there are several definitions, depending on how any one person perceives an image. The way Saussure looked at semiotics was different to that of Barthes, Saussure looked at the way language affected semiology, he believed language was the most important of all signs; however Barthes looked at the 'grammar' of narrative. Saussaure states "Linguistics is only one branch of this general science (of semiology)."
Victor Burgin however believes that there is no 'language' as such to photography, but more a system of codes, unlike in English, English (which relies upon the English language.) Burgin believes there is not such a simple connection with photography.
Semiotics allows us to interoperate the way the human eye views images and the meanings hidden in the image. Although the meaning in photographs may not always be obvious, it does not mean it is not there; semiotics is being able to understand where some of those meanings may be hidden and learning to read an image.