The publication also said that Charlize Theron is thought to be taking the part of Wegener's spouse Greta in the movie, which Kidman is also producing.
Although pre-production has started no release date for The Danish Girl had been announced as yet.
The Danish Girl will re-tell the story taken from the 2000 novel of the same name, by David Ebershoff.
Einar Wegener had stood in for a female model that his wife had been going to paint a picture of.
Because of the success of her artwork, Greta Wegener encouraged her husband to permanently take one the identity of a woman.
