Highlight Tone Priority.
HTP is supposed to reduce exposure then push the shadows in processing. Well, I've had a brief play at lunchtime and it's still left me wondering. I did shoot three images with it on and some with it off against a severly afflicted scene lighting-wise (dark interior and bright daylight through the window) It certainly brought up the shadows to at least a full stop over a 'normal, expose for the highlight' frame withought blowing the highlights.
What I'm not convinced about is this: is the sensor adjusting to the scene on a per pixel basis as some models can on white balance in full auto or just moving the whole histogram to the right in relation to the exposure?
If it's the latter then it's just what we do anyway (jpeg shooters) but if it's the former which I suspect it might be judging by the shadows then it is of real, practical use. I'll have the camera on 'P' for professional at the next wedding then ...
Any tecchies around here with in depth knowledge they'd like to share?