Morphing is a special effect in motion pictures and animations that changes (or morphs) one image or shape into another through a seamless transition.
Most often it is used to depict one person turning into another through 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Since the early 1990s, this has been replaced by computer software to create more realistic transitions.
this is a small example i made , actually it is not so accurate but it shows the meaning of the operation