Ok, so I think I've finally sorted the horrible washing out of h.264 Quicktimes - I had read that to fix it you:
Go to the movie's properties in Quicktime Pro, go to the Visual Settings tab of the video track, change the Transparency to 'Blend', set the slider to 100%, switch the Transparency back to Straight Alpha, scrub the timeline and save the QT.It didn't work.
Now what I have found certainly does work is export the Quicktime as a 100% Motion-JPEG encoded movie, and then from Quicktime Pro export that as h.264. This looks pretty much just like the original (gamma-wise).
Labels: compression, gamma, h.264, photo-jpeg, Quicktime, washing out