If we are talking cartoon logic then yes he can see her, but if we are talking real world logic then it depends, I believe in ghosts as I have seen them before, I'm a spiritual medium, but even though I have seen ghosts and spirits ut has never been how they looked like when they were alive, I can only see a shadowy form usually.
But there has been a few times where I've seen a ghosts appearance fully, and those times were only when the ghost reached out to me first and chose to communicate with me, from what I think the reason I could fully see their appearance is because they chose to show it. So it really depends on how you view the human in the comic for if they can see the ghost or not.