This is a fascinating question. Recently a lot of scholars from all disciplines have been working on this topic - philosophy, history, and psychology. Here are some thoughts on each of these topics.
Perception is what humans experience and internalize. All people perceive differently based on their experience, cultural background, and stage of life. All people have their own perspectives. In this sense, there is nothing called objective reality.
Memory is the process by which people store information. It is important to note that memory is not perfect and changes over time. We can even say that people interpret their memories. For example, we often say that people have selective memories.
Imagination is often linked to the free thinking and steam of consciousness. This an acceptable starting point, but when we realize that human perception and memory is imperfect and that we often fill in the gaps, the difference between imagination and perception and memory are closer than they first appear.
There are differences among the three types of sensory experiences. Most notably, there is a fundamental divide between perceptions, on the one hand, and recollections and imaginings, on the other. Perception is distinct from imagination and memory in that it presents objects with a certain sense of immediacy: when we see objects, they seem to be present directly before us in our environment; while the objects of our memory or imagination either don’t seem to exist now in front of us (although we may imagine objects in front of us) or are given to us as being located in the past or in some imagined world or in some location in this world other than that in front of us. Although there is a difference in kind between perceptual experiences, memories and imaginings this is often accompanied by certain differences in degree. Thus sensory episodes of imagining or remembering are typically less vivid and stable in their existence and nature than episodes of perceiving; while the latter appear to be less open to the influence of mental activity than the former. In addition, all three types of sensory experience play different motivational and justificatory roles; and these rational differences are at least to some extent phenomenologically salient. We are inclined and entitled to different beliefs in response to perceptions, memories and imaginings; and this is reflected by differences in what it is subjectively like to undergo these sensory experiences.
The nature of perception has always been one of the major topics in the philosophy of mind, while the opposite is true of perceptual memories and, even more so perceptual inaginings. In particular, not much attention has been paid to the similarities and differences between imagination and memory in their sensory forms, as well as to the fact that both are, from a phenomenal point of view, much closer to each other than to perception. The main aim of the conference is to remedy this situation and to get clearer about the nature of both perceptual imaginings and perceptual memories by comparing them with each other and with perceptions.Our sensory imagination is not completely unconstrained. What we can visualise, say, is restricted to the visible and, arguably, to what we have seen in the past or can extrapolate from our past perceptions