The filmmaker takes charge of the coming-of-age tale, adapted from the book by Kazuo Ishiguro, which tells the tale of three students whose world falls apart when they leave their boarding school.
The trio is played by Knightley, Carey Mulligan and Andrew Garfield, and Romanek insists it was almost impossible to make the Pirates of the Caribbean beauty appear plain.
He tells Britain's Daily Express, "It was difficult. She was eager and happy to do it because the role called for it. But even at her worst, Keira still looks astonishing."