The double exposure technique is a versatile, creative effect made by superimposing two videos to create a single clip. You can use Adobe Premiere Pro or After Effects to do this, but we’ll focus on Premiere Pro.
To begin, you need two video clips. One clip will need to have a white background, as you will be applying the “Screen” Blending Mode to it and having it become the container for your second video clip to be seen through.
On the clip with the white background, contrast is your friend. You may need to crush the whites and blacks using Curves in the Lumetri Color panel. Or adjust the exposure. This will ensure the second clip doesn’t appear through the white background and only shows over the subject of the first clip.
This quick tutorial video will show you how to do this, but keep in mind there are many ways to use this effect creatively. Often, you’ll see this technique applied by desaturating the screened clip. Some of the best applications I’ve seen use wispy, smoky, or cloud-like footage for the second clip (inverted if necessary).
This is a great technique to play around with and see what results you can produce. Enjoy!