Robert Rodriguez has revealed he made the cast of Sin City 2 paint portraits of their characters to help inspire them.
Jessica Alba, Mickey Rourke, Bruce Willis, Josh Brolin, Jamie Chung and Rosario Dawson are among the stars of the noir crime thriller which is filmed using green screen technology to recreate the style of Frank Miller's graphic novels on the big screen.
Robert, who co-directed Sin City: A Dame To Kill For with Frank, revealed he had a painting studio on the set of the film so that the actors could create what they thought their characters would look like to help them see past the green screen.
The director revealed at the film's Los Angeles premiere at the TCL Chinese Theatre: "I wanted to have a gallery of their paintings tonight, but we thought it might get lost.
"I was making them paint a self-portrait of their character so they could get more into the character, and also free themselves up creatively so that when they get back to the green screen they can imagine things that aren't there.
"Because you're just in green soup - there's nothing there. So you don't want them to be sitting in a trailer wondering what they're going to do next, so you keep them in a creative mode."
Frank added: "I've told Robert before that he should probably sell all his trailers, because his actors never get to go in them!"
Asked what the universe of Sin City represented to him, the 57-year-old graphic novelist teased: " That would be telling. Get all your friends to see number two and I'll show you in number three!"
Sin City: A Dame To Kill For is released in UK cinemas on August 22.