Been meaning to ask this for ages and another thread has just reminded me. I think I'm right in saying that there aren't any cameras that display raw data on histograms. All are subject to a jpeg conversion of some description even if you shoot raw only. For this reason, if shooting raw, I've generally adjusted picture profile to be as flat as possible. But I'm curious about the technical reasons why we can't see raw histograms or at least have a definitive indicator to warn of blocked shadows or blown highlights in the raw data.