Nowadays many movies use blue or green screens to create special effects. Most of movies use bluescreen and add background by using CGI (computer generated imagery). They use bluescreen to allows performers appear in any location in front of blue background without leaving the studio.
Soon after we edited it on the computer, we can move other features or element into it like earth background. So that they could appear to anywhere in earth, or any other world that could be appeared in real movies. Beside that, they also use the key backgound in the video signal. The video signal such as seperate camera, recorded video playback or digital sources is processed and overlaid with the key background.
Beside that,we can do chromakeying with any color on editing. But most of the time a pure blue or green are used because they are not present in human skin tones. Which color to use is something of a coin toss. Some folks claim that blonde hair keys better against blue. If we recording in DV format We found that green works just a bit better due to its higher luma content. The usual approach is to paint a wall with Rosco ChromaKey paint, which theoretically gives a pure color with little contamination from other locations on the color wheel. In my experience, though, we can just go to the paint store and get the purest green or blue they can mix. If painting a wall is impractical, for limited situations we can use blue or green cloth stretched as wrinkle-free as possible. In one show, we can even used green bulletin board paper from a local school supply store to extend the green screen onto the floor.
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