In the world of movies, special effects is quickly becoming the industry’s bread and butter. Movies like Star Wars, Willow, and The Fantastic Four have all used some magnificent special effects which all originated in a computer screen. People can shoot lasers out of their eyes, trains can become derailed, and whole planets can explode.
One of the most impressive forms of computerized special effects is Chroma-Keying, also known as green screen. Blue screens were used in the past, but green screens have become more of the standard because it’s easier to light and chroma-key out. In a green screen effect, an actor performs in front of a large green background. The image is put into a computer, and the green background is digitally replaced. Some movies have used this to make some exciting effects.
Films like 300, Sin City, The Spirit, and the tv show Sanctuary were shot entirely in front of a green screen and the entire location in the movies are computer made. You can put people in space, ancient Greece, under water, or any other crazy location you can imagine. And it’s not just the big Hollywood productions either. This is something you can even do yourself.
All you need to do a green screen effect are a green background (this can be a ready made green screen, a green sheet, or even a wall painted green you can get detailed information on making a green screen here: Creating a Green Screen and Then Renting it for Profit), lights, your camera, and video software capable of chroma-key.
The most important part of this effect is the lighting. Your green background needs to be evenly lit so it all is a single shade of green. Make sure there is no dirt on it. Remove any creases in the material and adjust your lighting to kill any shadows. You must also light your actor. Use your typical 3-point lighting on him (key light, fill light, and back light) and remember that for this effect to work best, the back light on the actor is very important to make him as separated from the background as possible.
Capture the footage into your computer and run it through any program that allows chroma-key. Some programs to use are Premiere, After Effects, Final Cut, Video Edit Magic, or Sony Vegas.
Once you’ve got your footage in the player, you’re ready to replace the green screen. The location of the function differs slightly from program to program (you might have to look through the programs help button to get there). Once it’s up, select the green background to be replaced, as tell it to be subtractive. This will result in the green becoming a white and grey checkerboard, while (if you lit correctly) your actor will be just fine. Now, any video or photo that you put on a video track below your green screen footage will take the place of the checker background.
Congrats! You’ve just performed your first green screen Hollywood style production!