I managed to lower the contrast to be similar, if not equal, to the untouched HD-DVD; now blue is less present than the first attempt, but whites are not clipped anymore, it seems:
http://screenshotcomparison.com/comparison/67000
http://www.sendspace.com/file/79z6ei
This is the best compromise so far; feedbacks are needed, as I'd like to finally begin to encode...