In a black-and-white shot for Interview magazine's September cover story, the actress faces the camera dead on, sans shirt.
She said she's had her body "manipulated so many different times for so many different reasons, whether it's paparazzi photographers or for film posters."
One notable example: The poster for 2004's "King Arthur" clearly enhanced her bosom a cup size or three. She would later refuse to allow her cleavage to be altered on a poster for "The Duchess."
"I think women's bodies are a battleground and photography is partly to blame," Knightley told the British paper, noting that it's easier to photograph a woman who's not curvy.
Photographer Patrick Demarchelier, whom she interviewed to go along with the pictures in the magazine, apparently didn't find the actress' requirement problematic.
"Everybody can take a good picture. Everybody is interesting. Everyone has an interesting face. Some people are more difficult or more nervous or more tired," he told her.
"When you do a movie, you have action, you're talking, you're moving. You don't see the camera. Taking a picture with a photographer, you don't talk, it's more difficult than in a movie for your body to relax, to be yourself."
Those who do want to see Knightley walking, talking and moving can see her on the big screen when "The Imitation Game" opens Nov. 28. Benedict Cumberbatch stars in the drama about Alan Turing.