There are two sources to go to in your inquiry about metaphors in photography. First and foremost is Susan Sontag’s work on this topic. She was the first intellectual to arrange and taxonomize the photographic "art" (as opposed to its merely recording function). Her astute observations took photography from a science to an art. She maintained that not only did a photograph reveal the overt subject but also the covert intentions of the photographer, because of the choices inherent in the composition, lighting, background, etc. – the artistic selections of the photographer. The second source is the fairly recent discipline of visual rhetoric, in which scholars treat visual imagery, including photography, as a hidden language of persuasion by metaphor, color choice, composition, etc. In that discipline, virtually all photography is metaphorical, in that it implies mental connections on the subconscious levels of the mental processes. A quick example might be the white picket fence in an advertisement for insurance. The metaphor is that an insurance policy will give your family stability and the realization of your dreams about a calm, protected financial life, a "picket fence" surrounding your "home," your life.