Production Notes: Chroma Keying and Green Screens

What Is Chroma Key Compositing?

Chroma key compositing, or chroma keying, is a post-production special effects technique used to remove the background from a photo or video so that a different background can be used behind the subject. The way this works is that a scene is filmed or photographed with the subject against a solid color background and during the keying process, that single solid background color is isolated and made transparent so that editors can insert a different background behind the subject. This means that the background color must offer a high contrast to the subject’s skin tone and that the subject must also not be wearing the same background color in order to have a clean key and prevent other elements from being replaced along with the background.

Chroma keying can work with any color, but green is commonly used today due to the rise of digital cameras and how they work. Most digital cameras and camcorders use what’s called a Bayer filter. The Bayer filter is a specific arrangement of red, green, and blue color filters that help create a color image. The pattern is 50% green, 25% red and 25% blue. With there being more color information offered in the green channel than the red or blue channels, green backdrops allow for a much cleaner and more detailed key when removing the green color.

Green screens are commonly used in newscasting as well as the video game and film industries. For some examples of how keying is used with CGI to create some spectacular visual effects in movies, watch the video below to see before and after scenes:

20 Amazing Movie Scenes Before and After Visual Effects by Screen Rant (YouTube)

If you are looking for a green screen studio to use for your next project, check out our online Nevada Production Directory for a list of companies in Nevada offering green screen studio rentals or drop by our office and pick up a free printed directory! You can also find additional services for post production editing here.

If you offer green screen options or post production services in Nevada and are not yet listed in our Nevada Production Directory, you can learn more about how to sign up for the NPD here.