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Before she begins her Wednesday morning, Iranian activist Masih Alinejad spends hours sifting through scores of videos and photos sent to her of women in Iran wearing white headscarves or white clothing as part of a growing online protest.

To campaign against the obligatory wearing of headscarves - or hijabs - Alinejad, last month, encouraged women to take videos or photos of themselves wearing white and upload them on social media with the hashtag #WhiteWednesdays.

"My goal is just empowering women and giving them a voice. If the government and the rest of the world hear the voice of these brave women then they have to recognize them," Alinejad told the Thomson Reuters Foundation by phone.

Under Iran's Islamic law, imposed after the 1979 revolution, women are obliged to cover their hair and wear long, loose-fitting clothes for the sake of modesty. Violators are publicly admonished, fined or arrested.

Although no official records have been collected, a report by campaign group Justice for Iran in 2014 found over 10 years nearly half a million women were cautioned and more than 30,000 women arrested in cities across Iran over the hijab law.

The #WhiteWednesdays campaign is part of a larger online movement started three years ago by Alinejad, a journalist who has lived in self-imposed exile since 2009. She has received death threats since her campaigning started.

She created social media platforms and a website called My Stealthy Freedom where women in Iran take photos of themselves without hijabs to oppose Iran's dress code.

The 40-year-old activist wanted to raise the visibility of her online movement so women could identify each other in the streets of Iran by wearing white, "the color of peace".

"I want people to talk. I want people to have a platform and talk together because having a free conversation is something Iranian society needs," said Alinejad, who now lives in New York.

Some of the videos, which are subtitled by volunteers, have several hundred shares on the My Stealthy Freedom Facebook page that has more than a million followers.

Some Iranian men have taken part in the campaign, and Alinejad also invites Iranian women who wear the hijab willingly to join as well - emphasizing that the campaign is not against hijabs, but being forced to wear them.

Alinejad said she doesn't consider herself courageous - unlike the Iranian citizens before the lens.

"They are more brave...Honestly, these are the leaders and I am following them," she said.