'It's amazing, I can't believe it,' Masturzo told BJP as the results were announced. The young Italian took the picture while on assignment in June 2009.

The photograph portrays women shouting in protest from a rooftop in Tehran, on 24 June. It is part of a story depicting the nights following the contested presidential elections in Iran, when people shouted their dissent from roofs and balconies, after daytime protests in the streets. The story as a whole was awarded first prize in the category People in the News.

It was selected from among 101,960 images submitted by 5847 photographers.

'I went into Iran before the election, because I wanted to take pictures of Iranians during this period, which also happened to be 30 years after the 1979 revolution. I would never have imagined what would then happen,' says Masturzo.

The photographer went into Iran with a tourist visa. 'I didn't want to use a journalist visa, because when you do, the Iranian government controls your movements.' However, he says, he still ended up being arrested five days before the election. 'When they released me and gave me back my camera (a Canon 5D), I was afraid to go back in the streets during the protests.'

Staying inside an apartment one night, Masturzo heard cries outside. He looked out a window and saw women shooting from the rooftops of buildings. 'I asked them why they were doing that, and they explained that they used to do the same thing 30 years ago. This was a way to protest.' That's when he took the winning image. 'I found it was the best way to speak about what was happening without going into the streets.'

Masturzo came back to Italy on 01 July. The next day a national network bought the rights for the pictures, as well as two Italian magazines. It also won a national prize, he tells BJP. The photographer would like to go back to Iran, but with his World Press Photo win, he doubts he will be able to. 'They know me know,' he says.

Jury chair Ayperi Karabuda Ecer commended the winning image for its quietness. 'I compare it to music - if you turn it up loud all the time you end up not being able to hear anything,' she told BJP. 'This takes the volume down. We really liked it as an image, it's attractively constructed and there's something enigmatic about it. We had no idea of what it was when we first looked at it, but nevertheless there's something about it that draws you in. It invites you to think differently and discover something you can find out more about afterwards.'

While a professional photographer took this year's winning image, the jury awarded a Special Mention recognising a frame grab from a video posted on YouTube in June 2009 during the post-election uprising in Iran. It depicts a woman identified as Neda Agha-Soltan lying on the ground after being shot in the chest.

'I am pleased that World Press Photo has provided an avenue for non-professional images that have a significant impact on the historical visual record,' says jury member David Griffin of National Geographic.

The jury considers an image for a Special Mention when it has played an essential role in the news reporting of the year worldwide and could not have been made by a professional photographer.