Faces of revolution
Pictures of protest in themselves are now commonplace and easy to find on the internet - yet without that extra spark, that individual story, they do little more than covering the first base of still photography: simply stating that this happened and this is what it looked like to the photographer, a matter of record.
Wide shots of thousands marching can mean very little and it's easy to make a small crowd seem larger in a picture; a simple figure in text captures the scale of a demonstration just as well.
Often the most powerful pictures focus on the personal, an individual. These pictures can be visually strong with an eye-grabbing composition, or in the heat of the moment, as with many news pictures, just snatched moments where the content is so strong that the framing is secondary.
At the extreme end of the spectrum is the death of a protestor, something that, if recorded on film, can move into the public realm and become a beacon for those who are fighting for one cause or another.
A few notable examples taken on protests that spring to mind include the death of Carlo Giuliani who was shot dead by an Italian policeman in Genoa during demonstrations at the G8 in 2001 and photographed by Jess Hurd among others.
To go further back Thich Quang Duc's self-immolation as a protest against the war in Vietnam, captured by photographer Malcolm Browne in 1963, or the tank man in Tiananmen Square in 1989 and earlier this year in London, Ian Tomlinson's death at the G20 protests.
In recent days, the face that has stuck in the mind is that of Neda Agha-Soltan who was killed during the current unrest in Iran following contested elections in June.
The exact details of her death are not yet known but Neda's fiance, Caspian Makan, spoke to BBC Persian TV about the circumstances of her death:
"She was near the area (of the demonstration), a few streets away, from where the main protests were taking place, near the Amir-Abad area. She was with her music teacher, sitting in a car and stuck in traffic. She was feeling very tired and very hot. She got out of the car for just for a few minutes. And that's when it all happened."
It's hard to write about such a personal moment from a distance. Neda's death is undeniably a tragic one, and there has been much written on her life in recent days, but it's the role the photograph of her last moment is now playing that I want to explore.
The picture, a frame grabbed from a video has two voices: the personal tragedy for both Neda and her family, and the other its widespread use as a political tool.
The image has now spread around the globe and is mostly seen on placards accompanied with the slogan, "I am Neda", a rallying point for Iranian opposition supporters around the world.
As with Neda's image, some of the examples above made their way to placards and political literature, and were sometimes moulded and used in a variety of contexts to meet different ends.
Every picture, be it of conflict or of peace, creates a line of trust between photographers and photographed - but once the image is out there, it's almost impossible to control.
As photographers, whether professional or amateur, we borrow the likeness (to use that Victorian term) of our subject, and even with the best intentions have to accept that every time we press the shutter, we are stepping into someone's personal space, something we should do as honestly as we can.