How did they do this “picture-in-picture”-like effect in old movies before digital video?


There’s a scene in the original 1971 Willy Wonka movie which is sort of like a “picture-in-picture” effect. You can view it [here.]( The main scene morphs into a square on top of a black background and there’s animated text that moves around and inverts and all this crazy stuff. I’m mainly interested how they sort of compressed the film frame onto a black background. I am wondering how they did this in 1970-71 on 35mm analog film before digital video and computers that could edit vide were a thing

In: Technology

That’s an optical effect. Movies were edited on film. That effect uses a “gate”. You copy one film onto another with a metal block in the way which blocks pamt of the image. Before you develop the copy, you run it through again with a block covering everything except where the block was in the first pass and instead of the main scene you have the inset scene. After this double exposure, you develof the film and you have film with the two scene elements merged.

I suspect they used the same technique from Mary Poppins in 1964. It’s live action with animation.