A woman seen from behind with 'Feminist' printed on her underwear.

Charlotte Jansen interviewed 40 artists from 17 countries as part of her effort to understand the role of women in photography — as subject and muse, and also as creators.

Cover of photography book 'Girl on Girl' by Charlotte Jansen.

“They can be a way to understand identity, femininity, sexuality, beauty and bodies,” she writes in a book excerpt published on CNN.com.

Jansen — a freelance writer, editor-at-large at Elephant magazine and author of “Girl on Girl: Art and Photography in the Age of the Female Gaze” — asks, “How should we look at women?”

“The photographs women take of women can be a tool for challenging perceptions in the media, human rights, history, politics, aesthetics, technology, economy and ecology; to get at the unseen structures in our world and contribute to a broader understanding of society,” she writes. “What you can get is not always what you might see.”

“Girl on Girl,” featuring work by Mayan Toledano, Maisie Cousins and Juno Calypso, among others, was published April 8, 2017, by Laurence King Publishing.