Katy Perry performed to five thousand screaming fans in LA, after strutting down the red carpet at the premiere of her new film, Katy Perry: Part of Me.

The film follows Katy's progress from gospel singer to pop star sensation and charts her failures as well as her success, including her short marriage to Russell Brand.

The movie is named after her song Part of Me, which was released in February.

The singer said she wants the film to uplift fans and explained: "Hopefully they'll be inspired if they have an obstacle but they have a dream as well, that they can get through that obstacle and go for it, and look for the dream."

Internet sensation Rebecca Black, who collaborated with Katy Perry, said she was a pleasure to work with, adding: "She is so outgoing and so much fun and she's so nice.

"She's just kind and she really cares about you. It was really nice to see that someone so huge in the industry, still be very grounded."

Katy Perry: Part of Me hits cinemas on July 5.