Hi, This is sort of hard to explain. You may just have to try it out.
When using the three-way color corrector there is subtle strange behavior when using the built in levels with GPU Accelaration enabled.
I discovered it when i was trying to crush my blacks to create an overall post Look. So i start really pushing my blacks and they don't really
look like they are getting really dark, although the waveform monitor show them really crushed. So i render or export the clip, set it on the timeline,
look at the waveform and it shows my blacks darker just not crushed. It even kept the uneven spikes just kissing the 0 line.
Using mercury playback Software only, everything is normal. You can try experimenting just by turning on the GPU accelaration, really try pushing
your blacks or whites in the master controls, and render. Look at your waveform after rendering. Then try with GPU Accelaration off. You may see
two drasticlly different results.
The Fast Color Corrector is not affected, so i am using this effect or curves to adjust luma levels. I have always used the Three-way Color Corrector
to correct my shots, I really like it, this is my CC of choice. Only noticed it since i purchased a new gpu enabled video card.
I am not sure why many tutorials always reccomend using the fast CC for removing color casts.
as it also throws your black balance off as well as mids and whites.