For myself, visualizing isn't exactly 'seeing'. It's just sight-like, in that the same general information about shape, color, arrangement, etc. can be pulled up, with effort. Closing the eyes isn't strictly necessary, but helps avoid the distraction of actual sight.
It's very sensitive to attention/intention: asked to visualize a person, I'll mostly imagine the face and general build – not even picking specific clothes – unless that person is very associated with some outfit. But if I think more about some specific prompt – say, "what were they wearing at some recent event", or "think about their hairline" – I can call up (or pick) reasonable details.
I suppose you could say it's no more vivid than it needs to be, and with concentration it becomes more vivid/detailed, but never quite like the solidity of a photograph. (Well, maybe while deeply concentrating with eyes closed, or half-asleep, or actually dreaming, there can be moments of seeming realism...)
It's very sensitive to attention/intention: asked to visualize a person, I'll mostly imagine the face and general build – not even picking specific clothes – unless that person is very associated with some outfit. But if I think more about some specific prompt – say, "what were they wearing at some recent event", or "think about their hairline" – I can call up (or pick) reasonable details.
I suppose you could say it's no more vivid than it needs to be, and with concentration it becomes more vivid/detailed, but never quite like the solidity of a photograph. (Well, maybe while deeply concentrating with eyes closed, or half-asleep, or actually dreaming, there can be moments of seeming realism...)