Someone will know this, because I can remember some pretty good details. I'm pretty sure it was a 70s movie with Elliot Gould. The main guy is a photographer who takes pictures of dog turds for some reason (like he's being avant garde, or has a weird obsession). There's a wedding presided over by a priest who has converted to millitant atheism. Near the end, a sniper shoots a woman, randomly, I think, and Elliot Gould gets her blood all over him and just wanders around in a daze for awhile, and rides on a subway with this blood still all over him.
Little Murders maybe?
http://www.imdb.com/title/tt0067350/usercomments
That's it. I recognize some of the pictures on http://www.asianworld.it/forum/lofiversion/index.php?t5266.html (http://www.asianworld.it/forum/lofiversion/index.php?t5266.html) I'll have to watch it again some time, it sounds good from the imdb thing (I don't remember it well enough to know for myself).