Chroma Keying

Also called “keying,” or “blue screen,” the process of overlaying one video signal over another by replacing a selected color with a second video signal. For example, if you shoot someone in front of an evenly-lit blue screen, you can use a chroma key function to render the blue completely transparent, thus revealing underlying video layers. The Chroma Key process was made famous by films such as star wars where spacecraft miniatures were composited onto starfield backgrounds.