UMBRELLA star Rihanna has a secret addiction to art collecting - which began after buying a painting by Rolling Stones legend Ronnie Wood. The R+B celebrated her recent 20th birthday by snapping up a portrait of reggae singer Bob Marley created by Wood - and admits she's now got the canvas-buying bug. Rihanna says, "I'm not a big spender, but I do like to buy art. My favourite canvas is a Ronnie Wood one. He painted a portrait of Bob Marley and as soon as I saw it I knew I wanted it. "It's very rare that you get a painting of a legend painted by a legend, so I had to get it."