The film is in competition at the Sundance independent film festival here in the US state of Utah, with prizes to be announced later on Saturday.
It features dozens of interviews with American women from all walks of life -- including Democratic House Minority Leader Nancy Pelosi and former secretary of state Condoleezza Rice -- who discuss the gender barriers they have faced and ways to lift them.
"Some of them were actually frightened to say something, they were afraid of losing their job. That shows this fear that we have in America, the fear we women have of speaking our mind," Newsom told AFP.
"Hopefully I'm encouraging other women and men to have a voice and stand up for women's rights, which are human rights," she added.
The film includes several statistics showing that gender inequality is worse in the United States than in much of the rest of the world.
"We're 90th in the world in terms of women in national legislatures, ranked behind Rwanda, Haiti, Cuba, Afghanistan and Iraq," Newsom says.
"It's humiliating. We should be learning from them. We think we're so great, but we're not," says the actress, who is married to Gavin Newsom, the former mayor of San Francisco and now lieutenant governor of California.
Women continue to make more than 20 percent less than men, an income gap that has changed little in recent years, according to the Washington-based Institute for Women's Policy Research.
Newsom says the problem is rooted in "capitalism taken to an extreme, without an element of public service and without an element of including women. It's also a little bit of greed."
She singles out the media for flooding magazine covers and television screens with images that she says reduce women to their outward appearance and bombard the audience with unrealistic standards of beauty.
A recent study carried out by the Annenberg School for Communication and the Geena Davis Institute on Gender in the Media found that male characters outnumber female characters by three to one in top-grossing American films.
The study found that women tend to play either traditional or hypersexual characters, that they were five times as likely as men to wear revealing clothing and three times as likely to be shown with a thin figure.
In animated films, women are frequently shown with waistlines that would be too thin to contain any internal organs, according to another study by the Annenberg school, part of the University of Southern California.
"Unfortunately, our media have been exported all around the world. We need to take responsibility and accountability for all the damage we cause... because we are not making the world a better place," Newsom said.
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