There are maybe two reasons for revamping a movie’s ad campaign: The film does bad business or it wins an Oscar. But rarely does a studio take a new advertising approach before a film even opens, as Warner Bros. did with its campaign for The Pelican Brief. Originally, the Pelican poster featured a larger-than-life Julia Roberts with another tiny shot of her and costar Denzel Washington in the corner. Understandably, Washington was not pleased. Stars of his magnitude routinely have a ”favored nation” clause in their contracts, which guarantees equal billing in all areas-including advertising. Did he threaten a lawsuit? ”Let’s say we sat down and we worked it out,” says Washington. Warner Bros. prefers to think of the change as a ”strategic” move. ”Our (original) concern was that Denzel was in posters for both Philadelphia and Pelican Brief,” says a studio spokesman. But the new ad, featuring the serious-looking duo huddled over a computer, has done nothing to hurt the film. Brief has grossed $61 million since it opened Dec. 17.