The green screen is used for special effects. It is difficult to make special effects for sci-fi movies, so they need to be keyed in, and then synthesized into the scenes we need. Actors stand in front of the green screen to perform, and then the green background will be deducted later to synthesize the special effects created by the computer. The green screen is the pre-production for the special effects.
Many movies and TV shows require grandiose backgrounds, and in order to save labor and material resources, they use green screen shooting and keying later. And some sci-fi movies need backgrounds that can't be shot, so they have to do special effects. Keying is the process of keying out specific parts of a specific picture and compositing them into other pictures. There are not only green screens, there are actually blue screens, but green screens are more widely used.
The surface of the object does not have a certain color, it can be selected as the background color. Because the surface of the object is a certain color and the color of the curtain is heavy, it is easy to snap off when keying. And green and blue is the color of our human body skin color is the least, with green screen and blue screen on the human body has no effect. Meanwhile the camera is most sensitive to green.
The choice of background color depends on the color of the subject. Theoretically, as long as the surface of the object does not have a certain color, this color can be used as a "curtain", of course, the actual operation of the most used is the blue and green two. Blue screen is actually still widely used in Asia, the original TV series shooting in the blue screen is often used. Because most Europeans have blue eyes, European Hollywood is basically green screen, do not have to worry about the eyes buckle off. And the use of blue screen, blue screen, although the Asian skin color has little effect, but the blue color in our costumes often appear, in order to facilitate keying, it is used green screen.