Robert Carsen’s production of the old Gene Kelly classic for Paris’s Théâtre du Châtelet (and which he hopes to bring to Broadway) isn’t entirely in black-and-white: “We use sepia toning sometimes. If it’s in a garden, it’s tinted green. If it’s indoors, it’s tinted pink. In the fantasy section, when it’s not in Los Angeles anymore or making a movie but dreaming of being on Broadway, in the Broadway melody, that all goes into gold and warm tungsten stage lights.”