This question means trouble. To answer it would be to define what an image actually is, or, even worse, to try to define the art in general. However, none of this is impossible - following an honest path towards what we feel is truth, we'll often recognize a great deal of support for our thoughts in what is inarticulately scattered about it throughout the history. So, once over: what happens in the communication with an image? The first, the most common, and the most important phenomenon is EMPATHY, feeling what image feels. "Give, empathize, rule" (datta, daya dvham, damyata - shall we peak into Upanishads). We become the image and feel everything it is. What truly happens is a resonance of feeling/thought structures that we found (or create) in the image, with the similar ones found in our subconsciousness. All this happens on an synesthetic level (synesthetic behavior being the phenomenon of taking an impression from one sense and expressing it in other) -the point being that in this aggregate state the ideas do not have concrete forms, and can therefore come to expression in any different shape - still carrying the same content. Just like the legendary and fascinative shock of deja - vu. (In fact, here is (by the way) an explanation for the popular wonder.) Most directly, we may say that in the image we find a synesthetic visualization of our own spiritual activities. The breadth of these is fascinating: as if we in deed tapped into a flow that unifies all of our mind, and therefore builds the unity of our subconscious I *. For example, the images of roundness help us recollect since they psychologically mean the whole. In the same way, looking at ornaments helps the contemplation (just consider mandalas) because they are visually "solved" - fluent, while the simple repetitive rhythm stimulates the flow without interruption (just as many people walk in the circle while thinking). These are just some extreme examples, while some more common cases are readily available. A sight of a down drawn lines of a weeping willow (sic! - the name) will cause some sorrow in us**. Very often the empathy towards image is sprung by existence of a certain center which serves as a "symbol of a man" - a center of us in the image, in relation with the rest of it. We recognize something as such center when seeing a situation of figure in relation with the environment, or whenever there is one figure as a dominant focus, or, especially, where the form itself suggests human or spiritual attributes.

The second main state of viewing an image is RELATION, towards it. Even if simpler and therefore primary, it just doesn't reach in us as deeply as empathy - and opposite, we do not get as deeply and clearly into the image. However, it must be that the state of relation is constantly (even if latently) present in every detail, as if ready to offer the opposition to emphatic approach. It is a rational, natural state (let's not get into some readily available gender siding) of clear definition: of us in relation to the other. That is why it is going to take over whenever empathy is disabled - most simply, in the portrait of a person which is looking straight towards us. Not to create a wrong impression: despite being so grounded in realism, it certainly is possible to have a relation with abstract elements.

Sometimes conditions just promote the distance, as when looking at the landscape with a path leading into it. This situation (possible even in more abstract levels) is called anthropocosmomorphism - we are in the described space, and react accordingly, weather to the warmth of the summer breeze in the landscape, or by the fear to the train rushing towards us from the screen, or to the strange cubic structure caving in on us (Vasarely).

We'll mention just one more specific case of relation, anthropomorphism - recognition of human features in the image. That certainly covers portraits, but more interesting is the example of a house which windows remind us of eyes. Recognizing the face pushes us immediately into a relation to "somebody else". Therefore image will be funny if the poor face looks confused, but if by chance our comprehension ventures into identification with it, we will feel, well, poorly. That's exactly how it works: not only sometimes, but mostly, empathy and relation interweave dynamically ***.

Since results can be exclusive opposites, it would be wise, should an argument ever arise around an innocent image, to refer to this little concept first for not only possible, but even probable help. Allow me just one more example of influence the image can have: it is a motoric sensation, an impression of movement experienced by perhaps the sight of lines that could be its trace. We should have a hard time trying to determine if this sensation originates from empathy or relation: the impressions of us being the movement and us making it (or following it, or observing it) are so similar - they are inseparable in the strange balance of opposites.

* - It is hard to resist smuggling in small print here how I feel that it is just this omnipresent and all - inclusive part of our being which should be regarded as the essence, the meaning, and therefore also the absolute definition of art, or, even further, a philosophical Reason.

** - We are of course interested in all the levels of abstraction. Limited to reality, this approach is a stronghold of solipsistic philosophic thought ("The world is my imagination" - Schopenhauer)

*** - Literature offers just too many spices to this already difficult correlation. Here is the motif - thought of Gaston Bachelard's "Poetry of Space" - a nice ramp for return to empathy: "I am the space which I am in."
how does the image work

Several elements here can create an impression of human face: we see two pairs of eyes, between the smaller there is a nose cutting down across the frame. But, this approach is not necessary, because resemblance isn't to obvious. That is why the final feeling alternates between the empathy with the constellation, and relation towards the "portrait". Which is here quite welcome: the image aims to create a diffused, scattered feel, confused in unfit environment, with unpleasant  needs and concerns.