I think of it as a process of:

• image in head
• bring up image over and over until it has some clear details that always stick around take shape
• isolate details, start thinking about why image is what it is, focus on your personal reaction to those details
• work backwards until you can draw a solid line from the image to its "source" irl

So like, if I have an image of something like, say, a man in a dirty raincoat and it makes me sad to think about it, after this process I might eventually think "it's sad because I see this man as a lonely victim" or something and now I have a full vibe to work with. I can start looking at this sad weary guy in his dirty raincoat, about what his life is like, how he got here, and like you said, the cruel world that isn't helping him, etc