Traditional Culture Encyclopedia - Traditional festivals - How did the movie special effects without WINDOWS come out in the 1980s?

How did the movie special effects without WINDOWS come out in the 1980s?

In fact, it was not only when there were no computers in the 1980s, but also around the 1990s, there were not many super users of computers. Most of them are superimposed on film. For example, you add a picture of a mountain with a blue background, and then remove your blue background, which is the effect of you in front of the mountain. The technology at that time could only remove the blue background. This is a common method at that time.