VENICE, Italy (AP) — "Joker" is rated R but director Todd Phillips says everyone was very careful with how they used violence in the movie.

The film premiered Saturday at the Venice International Film Festival where it is competing for the Golden Lion Award. It examines how aspiring comedian Arthur Fleck becomes the classic Batman foe.

Speaking in a news conference Saturday, Phillips said that they tried to make the limited violence as realistic as possible.

Star Joaquin Phoenix, who is garnering Oscar buzz for his performance, said his character was constantly evolving throughout the shoot. He said he studied a book about political assassins for inspiration, but that he also didn't want a psychologist to be able to identity Arthur as a type.

"Joker" opens in theaters on Oct. 4