Transitions

Wipe - gradual spatial transition from one image to another. One image is replaced by another with a distinct edge that forms a shape. A simple edge, an expanding circle, or the turning of a page are all examples.

As a word of warning, wipes should only be used if they are for a distinct purpose. George Lucas used them extensively for his Star Wars films, and although the purpose was to evoke memories of old pulp novels and serials as well as being inspired by Akira Kurosawa's Hidden Fortress (1958), he might have used them a bit too much. Nearly every scene is ended with a wipe, and he uses every type available, so much so that it has been criticised in some circles, not least in this video:




Dissolve - a gradual transition from one image to another. In film, this effect is created by controlled double exposure from frame to frame; transiting from the end of one clip to the beginning of another.

Often the dissolve can be used to show the passage of time, as such it is used in many montages. In this clip from Citizen Kane (Orson Welles, 1941) it is used to show the passage of time during a opera performance.




The dissolve can also be used to show the thoughts of a character, ie. a dream sequence, such as this one from Blade Runner (Ridley Scott, 1982).