This question means trouble. Maybe an easier one: 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 subconscious. 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 fascinating shock of deja – vu! (This, by the way, is an explanation of that 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 (consider mandalas) because they are visually "solved" - fluent, while the simple repetitive rhythm stimulates the flow without interruption (just as some people walk in a 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 figure, germ of the center of us in the image – in relation with the rest of it.

The second main state of viewing an image is the 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: of us in relation to something 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. And, despite the phenomenon being so grounded in realism, it certainly is possible to have a relation with abstract elements as well.

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).

Another specific case of relation is 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.

Although I haven't mentioned it yet, I can think of 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 exactly this omnipresent and all-inclusive part of our being which should be regarded as our essence, the Meaning, 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)

*** - To add to the amibvalence, 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.