I tend to think that clouds may provide a useful example to discuss but that we should not link this topic to closely to clouds so as to imply that clouds are the only or even a primary example. For the same reason I am concerned that focus on calling them "self-generated images" may be too limiting.
My suspicion is that this subject of particle flows is like eternity and infinity - the implications of this are huge and Epicurus is following the implications much more deeply than we would think of doing today. Those implications will derive from the presumption that all objects are constantly giving off streams of particles in all directions, and that these particles are constantly producing all sorts of results as their streams impact each other and interfere with each other. I think we should indeed be comparing these thoughts with modern optics/physics ideas like interference waves we discuss today. As with the example of clouds, the example of eyes and vision may be a primary example but not at all the only example. Is our understanding of magnetism today as deriving from particle flows really that much different than Epicurus is discussing? Is there really any reason to draw a bright line between our terminology of "energy" and what Epicurus was suggesting (that whatever exists has a real material basis to it)?
We haven't gotten yet to the discussion of magnetism as particle flows but that is going to be directly relevant: https://archive.org/details/lucret…e/n643/mode/2up
1743 Commentary on magnetism:
Excerpt from the text:
This is just a short clip - the whole section is important - we are not just talking about the process of sight.
As we continue through book four and the rest of the book we're going to confront many examples of illusions and phenomena that appear to derive from particle flows, and I think we need to keep a very open mind that his suggestions are not so ridiculous as they might seem. "Action at a distance", of which magnetism is maybe one of the easiest to grasp examples (since we can hold it in our hands so easily) must have an explanation other than magic or divinity, and as I understand the issues even as discussed today, particle flows remain a viable explanation. And if those particle flows we see in magnetism are really just one example of an essentially numberless quantity of particles flowing in all directions at all times, then Epicurus was right in considering this to be a very important subject and not just something for idle speculation.