Katy Perry and her parents "agree to disagree" on her sexy image.

The 'Teenage Dream' star's parents Keith and Mary Hudson are Evangelical Christian pastors and while the singer - famed for her provocative image and straightforward lyrics - is close to them, they don't see eye-to-eye on her career choice.

Katy explained to US TV talk show host David Letterman: "There's a dynamic between children and their parents that sometimes you can agree to disagree, and we definitely do that."

The host also showed the 25-year-old star a risque picture of her nearly naked on the cover of a magazine, and asked her: "What does God think of that?"

Katy joked: "That's side boob."

When asked whether her parents understand such images are simply part of showbusiness, Katy replied: "Uh, I don't know if it's the 'understanding' that they do.

"I think there's some grunts and moans and a couple of 'Oy veys.' "

Katy - who is engaged to British comedian and former drug addict Russell Brand - also told how pop music was an important factor in making her deviate from her strict Christian upbringing, when she discovered contemporary artists.

She added: "I sang 'Oh Happy Day' starting at nine. 'His Eye Is On The Sparrow' too. Then I discovered bands like Queen, and the Beach Boys, and of course The Beatles, and I just found out that the world maybe wasn't so flat."