For the last few years, the great American newspaper photographic libraries have been selling off their collections. I have been collecting some of the startling photographs of the Indian civil disobedience movement in the 1930s and I have uploaded some of them to this site. The captions are taken directly from the news agencies that commissioned the photographs and have some interest in themselves. They ought to appear if you hover the mouse over the photograph.
I have also written something about colonial violence here.