“This happens to the mpeg-2 output whether a file such as a .mov is imported into Vegas”
I had the same problem when bringing in .mov files from final cut. Somehow quicktime files, rendered out to mpeg 2, get a lot of adjustments added to the video as it renders. I apply the computer rgb to studio rgb preset in the vegas color correcting plug-in. This fixes the problem perfectly. Not sure why or how it works but it does. I fount out the hard way when taking my dv tapes to the station and all the colors were oversaturated and the whites blown out. I think it is a mac thing. (hehe)
“Note that Vegas does not work with Y’CbCr values directly. It needs to first convert the values into a R’G’B’ format- the two relevant ones are described below. Unfortunately, there is no scheme for indicating which color space is which. So, programs can’t tell which color space is being given to them.” previous statement taken from website below
https://www.glennchan.info/articles/vegas/colorspaces/colorspaces dot html