For starters you might try getting pictures from websites who have clearly shows interest in right to information. That could be for example Arvind Kejrival and Anna Hazare related websites of anti-corruption movements. I suppose not just these but every political party should be happy to release their photos under compatible licenses. They can consider it as free publicity and we can finally have images of events and politicians which our articles lack. You can try government websites also, but i guess they won't reply any sooner. But these parties might reply quickly and favourably too.