A change of scene

摘要

Films and television share a unique language for visual storytelling. One feature of this language lets us move through space and time in ways that are impossible in real life. For example, in a stage play, there needs to be some continuity of time and place: if a character is in the kitchen at one moment, he or she can't be behind the wheel of a speeding car in the next moment. But this kind of abrupt transition happens all the time in films. The simplest and most familiar way to get from one scene to another is via the cut. To create a cut, you can literally take two pieces of film, cut them at frame boundaries, and tape them together. The cut belongs to a general class of transitions: visual effects that form the boundary between different scenes. Let's say that we're watching scene A and we want to go to scene B. If the transition takes many frames, then at each step along the transition we conceptually take the appropriate frames from A and B and combine them to create a new image. The cut is the simplest transition. It takes zero frames to execute and simply stops showing A and starts showing B. Perhaps the next most familiar transition is the dissolve (also called the cross-dissolve), where we smoothly blend from A to B. A popular variation on the dissolve is the fade to black, which is just a dissolve where the B scene is a black frame. Many video-editing programs ship with a collection of ready-to-use transitions. The author discusses the field and then presents some transitions which he has developed.