While these sorts of effects have been used in films before, because of Jackson’s significant role in the movie, the number of shots that had to be de-aged by the post production was quite significant.
Because Captain Marvel is set prior to the events of most of the films in the Marvel Cinematic Universe, but includes the character of Nick Fury, who we know well from those movies, the film had to use visual effects to de-age Samuel L. Jackson.
According to visual effects producer Victoria Alonzo…