Bryan would you agree or disagree with saying that the faculty of prolepsis operates on "images?"
Agree, certainly. Just as all our senses. We smell and see the film that comes from our meal, for example.
And do you see any connection between the Centaur / image example in Lucretius and prolepsis?
Yes you can have real and immediate impressions of centaurs, particularly if you are asleep or crazy. But if you are sane and awake those impressions lack continuity -- when you are sane and awake you do not see centaurs frequently.