First, the foreground image is run through a chroma key filter. There are two steps in the process of combining the images. The green screen effect does that by looking for a specific color (like green, for example!) in the foreground image and then erasing any portions of the image that contain that color. The trick is to make portions of the foreground image transparent, allowing the corresponding parts of the background image to show through. Normally, you'd only be able to see the image in front, since it would block your view of the background image. The two source images are stacked in layers, one in front of the other.

The green screen effect works by combining images from two sources into a single image. It emphasizes ease-of-use and simplicity while still enabling you to achieve excellent results. Green Screen by Do Ink makes it easy to create green screen videos using your iPad. You know what a 'green screen' effect is, right? It's used in the movies to make it look like the actors have landed on an alien planet, and it's used on TV to make it look like your local news announcer is standing in front of an animated weather map.

Animated earth spinning green screen