How do you get the grey hulk in incridible hulk?

The Incredible Hulk is a 2008 American superhero film based on the Marvel Comics character the Hulk. It is directed by Louis Leterrier and stars Edward Norton as Dr. Bruce Banner. It is the second film to be released in the Marvel Cinematic Universe. This film establishes a new backstory where Banner becomes the Hulk as an unwitting pawn in a military scheme to reinvigorate the supersoldier program through gamma radiation.