rotoscoping

Có thắc mắc về chuyện Celine Dion hát chung với Elvis Presley thiệt hay giả không? Giải thích đây.
"Dion spent hours on the stage singing her part of the song several times without an audience or anyone next to her, looking to her side on cue.
Then she did the routine again with a Presley body double who lip-synced Presley's song and matched his moves from his 1968 performance.
Finally, all three elements — Dion by herself, Dion with the body double and the original Presley performance — were combined through editing and a technique called rotoscoping, which traced Presley from the original footage by cutting him out.
"Rotoscoping allows you to take one image from a pre-existing piece of video and puts him a whole new environment — completely new use of that same piece of video," Disney digital media designer Joe Husung said." (lượm tin và hình từ ABC News)
Cool, eh?