Remove decal "shadows" from windows ?

[Racer57]

Is it possible to remove an decals "shadow" on a cars windows ?  There is no residue from it, but when you look at the right angle or get the window wet, you can still see it. I've used Prep-Sol, rubbing and polishing compounds with zero luck. Any ideas ?

[Mr Cuda]

 The shadow is actually the lack of oxidation where the decal was. Polishing the glass around the old decal, and ceramic glaze is all I can suggest.

[Cuda Cody]

Time will help.  The ghosting will slowly fade over time. 

[Cuda Cody]

The same thing that caused, could fix it.  The lack of UV light can create the ghosting and if you give it time, the exposing of UV light can help fix it. 

[JH27N0B]

I'm reminded of a car I used to have, that when I'd look at my rear view mirror at night, I'd notice a faint image in my lower back window that would appear when street lights or headlights shown on that window, for some colleges law school.
I don't recall if I could ever see it during the day, or even from outside the car, just from inside looking at the back window.
It was a daily driver so it didn't bother me too much.  And I didn't want to get carried away trying to work on that window anyway, for fear of screwing up the defroster grid.
It never went away as far as I can recall.