History

Linwood Dunn Began the first use of the chroma key in 1933.Linwood Dunn used an early version of the travelling matte to create "wipes" – where there were transitions like a windshield wiper in films such as Flying Down to Rio  , Working for RKO Pictures.

Dunn designed numerous special effects with his homemade optical printer.

The printer consisted of a modified motion picture camera set up on a solid base with a special precision motion picture projector---both driven in synchronization while the camera photographed the film carried in the projector. Through this film-copying process, the image in the projector could be modified in unlimited ways."