gets a new look !
On the eve of her 16th birthday, Sylvie's father needs cash to stay in his castle so he sells Sylvie's favorite thing, a painting of Alain, the lover of Sylvie's grandmother, killed in a duel. Alain's ghost lives in the castle and Sylvie senses his presence, thinks she loves him, and fears that romance from the living will never come her way. Dad prepares a midnight surprise for Sylvie and her party guests: the appearance of the phantom. He's hired an actor, but two young men in love with Sylvie also volunteer to don white robes: Fred, the rich kid who bought the painting, and Ramure, a jewel thief in hiding. The youths declare their love, and Alain's ghost helps resolve all.
Source : IMDb
The special effect of the ghost appearing was achieved by filming through a glass pane and using two identical sets. Through the glass, the primary set would be visible. This was a regular set where all actors appeared, except the ghost (Tati). At the same time the reflection would be visible of the second set, placed at a ninety degree angle to the primary set. This set was covered entirely in black velvet, and the only actor on this set was Tati.
Source : Wikipedia