Are you sure what you see is real? Many of the characters we see no longer exist or never existed, but thanks to this system, they make them appear "where they are not", by taking their photos or video clips from a bygone era, but which seems current. Using green screen and chroma key. You shoot a scene with a compact, uniform background color so that the foreground subject can be easily separated in post-production and the background can be replaced with any color...