There’s a moment in Portrait of a Lady on Fire, filmmaker Céline Sciamma’s exquisite new film, when painter Marianne (Noémie Merlant) gives up on an early attempt to capture the likeness of her subject, Héloïse (Adèle Haenel). She’s been commissioned to paint the young woman as a way of ensuring a favorable marriage for her, but Héloïse is so against the idea of marrying (she’s only recently returned from a convent following her sister’s untimely death) that her mother (Valeria Golino) insists she can’t know she’s being painted at all. So Marianne has three-fourths of a portrait—a bodice and shoulders in an emerald green gown—but nothing above the neck, as daily…