Emma Watson has revealed shooting The Perks Of Being A Wallflower is her "graduation" from her Harry Potter alter-ego Hermione Granger.

The 22-year-old, who plays rebellious and popular high school student Sam in Stephen Chbosky's coming-of-age drama, said shooting the scene where she stands up, in a car, as they drive through a tunnel made her feel like she really had left Hogwarts behind.

"I started as Emma with some Hermione still left in my system. I went through the tunnel and I came out ready to start something new," she told Entertainment Weekly.

Emma revealed the film, which also stars Logan Lerman and Ezra Miller, has been a life-changing experience.

"At our initial meeting, he [Stephen] said, 'Okay, not only is this going to be one of the most important parts you play, you're also going to have the summer of your life and meet some of your best friends'," she recalled.

"I thought, 'That's quite a claim. Who is this guy?' Everything he said came true," she added.