Editing Forrest Gump (section)

=== Visual effects ===
[[File:ForrestGumpJFKScreenshot.jpg|thumb|right|alt=Black-and-white film screenshot showing the main character on the left looking toward another man, President Kennedy, (voiced by actor Jed Gillin), on the right. Kennedy is smiling and looking to his left. In the background, several men are looking in different directions and one is aiming a camera.|Gump with President Kennedy. A variety of visual effects were used to incorporate Hanks into archive footage with various historical figures and events.]]

[[Ken Ralston]] and his team at [[Industrial Light & Magic]] were responsible for the film's visual effects. Using [[Computer-generated imagery|CGI]] techniques, it was possible to depict Gump meeting deceased personages and shaking their hands. Hanks was first shot against a [[Chroma key|blue screen]] along with reference markers so that he could line up with the archive footage.<ref name="DVDEyes1">{{cite video|title=Forrest Gump-(Through the eyes of Forrest Gump)|medium=DVD|publisher=[[Paramount Pictures]]|time=12:29|date=August 28, 2001}}</ref> To record the voices of the historical figures, voice actors were filmed and special effects were used to alter [[Lip sync#In films|lip-syncing]] for the new dialogue.<ref name="BookChanges">{{cite news|last=Mills|first=Bart|title=In 'Forrest Gump,' Historical Figures Speak for Themselves|url=https://pqasb.pqarchiver.com/chicagotribune/access/24184772.html?dids=24184772:24184772&FMT=ABS&FMTS=ABS:FT&type=current&date=Jul+08%2C+1994&author=Bart+Mills.+Special+to+the+Tribune.&pub=Chicago+Tribune+%28pre-1997+Fulltext%29&desc=IN+%60FORREST+GUMP%2C%27+HISTORICAL+FIGURES+SPEAK+FOR+THEMSELVES&pqatl=google|format=Fee required|work=Chicago Tribune|date=July 8, 1994|access-date=June 13, 2010|archive-date=July 7, 2011|archive-url=https://web.archive.org/web/20110707202525/http://pqasb.pqarchiver.com/chicagotribune/access/24184772.html?dids=24184772%3A24184772&FMT=ABS&FMTS=ABS%3AFT&type=current&date=Jul%2B08%2C%2B1994&author=Bart%2BMills.%2BSpecial%2Bto%2Bthe%2BTribune.&pub=Chicago%2BTribune%2B%28pre-1997%2BFulltext%29&desc=IN%2B%60FORREST%2BGUMP%2C%27%2BHISTORICAL%2BFIGURES%2BSPEAK%2BFOR%2BTHEMSELVES&pqatl=google|url-status=dead}}</ref> Archival footage was used and with the help of such techniques as [[chroma key]], [[image warping]], [[morphing]], and [[rotoscoping]], Hanks was integrated into it.

In one Vietnam War scene, Gump carries Bubba away from an incoming [[napalm]] attack. To create the effect, [[stunt actor]]s were initially used for [[compositing]] purposes. Then, Hanks and Williamson were filmed, with Williamson supported by a cable wire as Hanks ran with him. The explosion was then filmed, and the actors were digitally added to appear just in front of the explosions. The jet fighters and napalm canisters were also added by CGI.<ref name="DVDVietnam">{{cite video|title=Forrest Gump-(Seeing is Believing: The Visual Effects of Forrest Gump-Vietnam)|medium=DVD|publisher=[[Paramount Pictures]]|date=August 28, 2001}}</ref>

The CGI removal of actor [[Gary Sinise]]'s legs, after his character had them amputated, was achieved by wrapping his legs with a blue fabric, which later facilitated the work of the "roto-paint" team to paint out his legs from every single frame. At one point, while hoisting himself into his [[wheelchair]], his legs are used for support.<ref name="DVDLegs">{{cite video|title=Forrest Gump-(Seeing is Believing: The Visual Effects of Forrest Gump-Lt. Dan's Legs)|medium=DVD|publisher=[[Paramount Pictures]]|date=August 28, 2001}}</ref>

The scene where Forrest spots Jenny at a [[peace rally]] at the [[Lincoln Memorial]] and [[Lincoln Memorial Reflecting Pool|Reflecting Pool]] in Washington, D.C., required visual effects to create the large crowd of people. Over two days of filming, approximately 1,500 [[Extra (actor)|extras]] were used.<ref name="DVDEnhanReal">{{cite video|title=Forrest Gump-(Seeing is Believing: The Visual Effects of Forrest Gump-Enhancing Reality)|medium=DVD|publisher=[[Paramount Pictures]]|date=August 28, 2001}}</ref> At each successive take, the extras were rearranged and moved into a different [[Cartesian coordinate system#Quadrants and octants|quadrant]] away from the camera. With the help of computers, the extras were multiplied to create a crowd of several hundred thousand people.<ref name="HankSign" /><ref name="DVDEnhanReal" />