No.

When I'm fully awake, the mental images are more like someone attached a new camera with a field of view that ends at the edges of the object/scene I try to generate.

Okay, forget everything outside that field of view in your real vision.

If you could crop your real field of view somehow to just the photo in question, then would it be as though nothing changed?

(Like, I get that things outside the phone image would change, but does the image your imagining change? Does the sensation change?)

The details get better or near photorealistic when I'm about to doze off.

When I wide awake, parts of the image are "gone" when I'm not focusing them.

Also, the sensation of seeing in my mind does feel different. It's like there is some different place where that image is showing up.

Even if I imagine the mental image to overlay with my real vision, it feels like it's "added" somewhere between my conscious mind and the outside/real world.