hey everyone!
I cant find a way to invert mastergrade, or any of the built in colorgrade tools.
I just want to whitebalance a plate then add cg then add the reverse whitebalance to the end of the comp all in linear of course.
My crazy workaround is to split RGB and multiply them one by one and then just negate the multiplication values manually in the end, thats pretty crazy and annoying though
Edit: nevermind look node = CDL that can be inverted I am good 
I hit the limits of the CDL Look node last week. Definitely check the inversion against the original.
Most of the time it’s great though.
good to know! just doing a slight multiply to neutralize a plate should be fine but good to know there is a limit.
Keep forgetting that I am not in everything is 32bit nuke land
I feel like the thing I hit wasn’t due to bit depth. I think creating negative values and messing with the gamma is something you can’t quite come back from.
In my case I went back to using the CC’s histogram for my grade and invert.
another of those things I want to find out why exactly !
the math behind a cdl is pretty simple shouldnt be that hard to figure out what happend, mind sharing the values you used?
The formula for ASC CDL color correction is:
something something horizontal line test… something … i need to do more maths I am getting rusty
Exposure node?
Or, wouldn’t it be cool if the Matchbox nodes did this with the -100% slider?
I just tried to break it again using what I think is a similar effect, but it’s working fine for me now. Haha.
I wonder if I knocked something down to integer space at some point, or clamped something. I’ll update if I manage to break it again.
UPDATE: found it. Set your power to 5 and look at the shadows.
And I’ll acknowledge that setting your power that high is bananas. I’ve got a spot with someone in an off-white room so dropping the gamma way down really helps to see all the grime on the walls which are supposed to be clean.
Don’t beat yourself up 
. I have also found a clipping problem with CDL. I’m sure that @finnjaeger always does a round trip test before rolling out a balance grade!
It is nice that it has an invert feature but USE WITH CAUTION. Always round trip.
yes of course!
I go more crazy and even difference the original plate with my comp and merge in the untouched plate for the parts that werent supposed to be changed to retain original grain where possible and only regrain the parts Ive worked on.
in Nuke I moved on from cdl to more
elaborate gamut calibration even .
Self thoughts about that. Could you imagine doing your first White balance with just a divide node (your rush against a color source of your chosen zone), do your comp and just re multiply with the same color source at the end of the tree???
Not in front of the machine but just wondering out of curiosity…
Yea if you have a linear source that should work just fine unless you have things that are 0 or negative then maths turns a bit crazy.
I used to multiply images with a white constant set to X to change exposure before we had the mastergrade and I didnt know how ancdl worked …
The Look node has an invert function.
