Morphing

Morphing is a special effect in motion pictures and animations that changes (or morphs) one image into another through a seamless transition. Most often it is used to depict one person turning into another through some magical or technological means or as part of a fantasy or surreal sequence. Traditionally such a depiction would be achieved through cross-fading techniques on film. Since the early 1990s, this has been replaced by computer software to create more realistic transitions.In early feature films a morph would be achieved by cross-fading from the motion picture of one actor or object to another. Because of the limitations of this technique the actors or objects would have to stay virtually motionless in front of a background that did not change or move in the frame between the before and after shots.Later more sophisticated cross-fading techniques were employed that faded different parts of one image to the other gradually instead of fading the entire image at onceThe effect is technically called a "spatially-warped cross-dissolve".
Morphing software continues to advance today and many programs can automatically morph images that correspond closely enough with relatively little instruction from the user. This has led to the use of morphing techniques to create convincing slow-motion effects where none existed in the original film or video footage by morphing between each individual frame (see optical flow). Morphing has also appeared as a transition technique between one scene and another in television shows, even if the contents of the two images are entirely unrelated. The software in this case attempts to find corresponding points between the images and distort one into the other as they crossfade. In effect morphing has replaced the use of crossfading as a transition in some television shows, though crossfading was originally used to produce morphing effects. Morphing is used far more heavily today than ever before. In years past, effects were obvious, which led to their overuse. Now, morphing effects are most often designed to be invisible.