Cinematography: Green Screen: An Open Learning Guide

The process of creating a "green screen" shot has two main parts: shooting and post production.

Your best bet to get the correct exposure is to run a few tests in a methodological fashion.

If you can't afford to run tests then light the green screen at about 1 stop over key (i.e. light your greenscreen to reflect twice as much light as your foreground elements and then set your camera's exposure to comfortably capture the foreground elements).

Try to limit the amount of reflected green light bouncing from the screen onto the actors (this can be achieved by careful lighting; by moving the foreground elements as far away from the green screen as possible or by simply covering unused sections of the green screen in black)

One way to check that your exposure is about correct is to place a bit of white card under the key light and then view the scene through a green filter. The white card should "disappear" against the green screen.

No, you can use any colour screen you wish. Any compositing software worth its place in this world will be able to chroma-key any colour. Blue and Green are often chosen because the human skin contains very little blue or green pigment. Green screens are often used for shoots outside as sunlight can register on a camera as "blue" causing problems when chroma keying.

Use a video camera with the least chroma subsampling (i.e. 4:4:4 is best). It is possible to get minimally acceptable results from DV (4:1:1) or HDV (4:2:0) but your life will be easier (and the resulting key considerably better) if you use a higher quality capture medium. Since keying relies on color information that is disregarded as part of any color space reduction from 4:4:4, all lossy compression formats will result in decreased edge detail.

Serious Magic has a program called Ultra that uses vector keying, rather than chroma keying.

Source and licence

Text adapted from Movie Making Manual/Cinematography/Green Screen by Wikibooks contributors under CC BY-SA 4.0. Paragraphs have been selected and abridged, and formatting adjusted. This adapted text is shared under the same licence. Contributor history.