Animated and Children's Movies

How does a movie green screen work?

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08/09/2009

===It's very simple actually. A green screen is a large green sheet that goes on the wall. When a person films a video in front of a green screen, they put it in an editing software with chroma key. Chroma key is the removal of a single color, therefore when chroma key is activated, the green gets removed, and ANY background gets inserted. That's why you can not wear green against a green screen, because if you wore a green shirt for example, it would be invisible and you would see the background you inserted instead of your shirt. Basically you can do "green screening" with any color, but green and blue are the furthest away from your skin color. That's so your skin isn't invisible If you did a white/black screen, there's a good chance your skin would be invisible That is why they use green. Hope that answers your question !! =) === A more technical explanation about this topic would be helpful. A dedicated color camera with RGB output is focused on the painted green screen wall. Such as you would find in a TV weatherman's studio. The green color that the camera sees, is sent to a switcher that has chroma keying abilities. Once the chroma keying is turned on, two adjustments are usually set for dissolving the green from the video. First, a range of colors on the switcher is adjusted to find green. the other control is adjusted to find the saturation of the color green. Now the green color should be dissolved and a blank screen seen. What has happened to the green color. In electronics, when two voltages are generated and come together 180 degrees out of phase, they cancel. When the camera provided one voltage, and the switcher provided an identical voltage, but 180 degrees out of phase, cancellation occurred and the video is now sent down stream where an overlay may be added, such as a states weather map, or any other video..