Katy Perry's 'Prism' was going to be a "dark" album, until she wrote empowering first single 'Roar'.
The singer started to pen songs for her latest record after the breakup of her marriage to comedian Russell Brand in December 2011, but once she and co-writer Bonnie McKee had written the empowerment anthem, released as the album's first single, she started to see things in a different way.
Bonnie told Radio.com: "She was kind of coming out of sort of a dark place when she was setting up 'Prism'. She was talking about wanting to explore her darker side.
"['Roar'] felt very empowering from the beginning. It was all about getting the right words together so it would have this visual hook.
"[After that] 'Prism' went from being a dark album, to being an empowering album full of light."
Katy, 29, has previously spoken of the way 'Prism' changed when she and Bonnie - who has previously collaborated with her on hits including 'California Gurls', 'Last Friday Night (T.G.I.F.)' and 'Teenage Dream' - were writing it.
She said: "There's not really any darkness on the record. There's definitely some textures and colours but I think I was saying that when I was going through a different phase, but I really let that light in."