When Ms. Moayeri got word of protests at Tehran University, she found students and riot police throwing stones at each other. Despite her fear of arrest, she started snapping photographs.

A stone hit her leg and some police officers blasted fire extinguishers, filling the air with billowy white fumes that resembled tear-gas smoke, she recalled, as the protests spilled outside the university’s gates.

“Suddenly this young woman appeared through the smoke, covering her face with her head scarf and flashing a victory sign, I snapped some images,” she said. “I never figured out who she was. Only when I came home I saw the picture had power.”

Thousands were arrested, 25 people died, the authorities tried to control the news and Ms. Moayeri possessed an image that had captured it all. As a freelancer who had worked in Sudan, Somalia, Pakistan, Iraq and elsewhere, she had many places to sell the picture, but also knew that if her name were published she might get into trouble with the authorities.

She ended up selling the image to Iran-based photographers for The Associated Press and Agence France-Presse. It quickly spread via social media as the symbol of the protests in Iran. There was no contract, and Ms. Moayeri said she still owned the rights to the image.

After six months she decided she had waited long enough to take public credit for the image. Ms. Moayeri sent it to the annual Iranian Photojournalists Association and won first prize. She did not get in trouble.