Andrew, I've got photos of seven or eight candidates, all with some claim to authenticity and none of them positively identified by members of Titanic's crew. Some were taken on in the area of the sinking on the morning of April 15th. I find none of them truly credible. The one known as the Rehorek berg is described on this site. It has the merit of being possibly the right shape, with a roughly vertical face that would throw ice on the ship's deck. It's weakness is that the photo was taken well after the sinking.
The one in ANTR has no real claim at all. It was taken well after the event and the red paint story seems rather unlikely.
The real truth is that we just don't know who dunnit.