On the one hand it's much more realistic and detailed than an after-image; if I picture a red apple, and someone asks what kind of apple it was, I can retroactively say "oh, like a Red Delicious, really dark and shiny and with that concave part, not at all like a Macintosh or whatever. But it was a bit rounder than a normal Red Delicious probably because I was averaging towards a kind of typical 'red apple'."

(FWIW I think I'm near the upper end of detailed visualizing.)

But on the other hand it isn't located in my visual field, it's kind of in its own separate visual field. It doesn't have a spatial relationship to the objects in front of me and doesn't occlude them (although when I'm visualizing something carefully I lose a lot of my awareness of what I'm actually looking at because I'm not attending to it, even if my eyes are wide open).