The other way to do it - I think Disney used it in the original Haunted mansion is with the invisible UV paint. You would need to be a pretty good artist though, as you would have to paint the evil picture on top of the good picture. then when the UV lighting is turned on you see the evil picture.
This shows one of these:
DoomBuggies > Explore the history and marvel at the mystery of Disney's Haunted Mansion attractions!
I wonder if you could refill old empty printer ink cartridges with the UV paint and use your computer to print the picture in the UV paint?