LUTs Not Exporting Correctly

I'm currently working on some LUTs to be used with iPhone footage, but I can't get them to export correctly. Whenever I save the LUT and then apply it to the same clip that I created the LUT on, I get a different look. Most of it stays the same, but the skin tones are darker and more saturated. When I use the LUT outside of Davinci in Final Cut Pro X, I get what looks like the LUT on 25% transparency.

Here is a still from the original video.

Original Image

Original.jpeg (958.37 KiB) Viewed 6885 times

Here is a still from Davinci with the desired look.

LUT_Out.jpeg (941.25 KiB) Viewed 6885 times

Here is when I use a LUT generated from the desired look above.

LUT_In.jpeg (939.51 KiB) Viewed 6885 times

Any ideas on why this is happening?

And here is the LUT when used in Final Cut Pro X.

LUT_FCPX.jpg (667.11 KiB) Viewed 6777 times

How was the LUT generated? If it was generated in Resolve, what specific controls were used? Be aware that only normal lift/gamma/gain, Contrast, Pivot, Log, Sat, Hue, Curves, and Tint apply -- no keys, no windows, no sharpening.

I would test the workflow with known test signals like SMPTE color bars and a grayscale pattern and see what happens. I would also avoid monitoring within Mac OS and instead use a color-managed output to a calibrated display so that you know what's actually happening to the signal (vs. what the OS does to it).

No secondary hmm ? Like color boost, temp, ...

The easiest way to think of what LUT in theory can do and what not is imho this: LUT can describe non-spatial color transforms only. Which automatically means no masks, no filters (sharpening, blurring etc) and so on that rely either on pixel location in image or values of adjascent pixels.

LUT also has limited range, where certain input value range is mapped to certain output value range (usually both normalized 0.0-1.0), so open-ended values like linear float data must be clipped or shaped depending on use case.

No secondary hmm ? Like color boost, temp, ...

Those can work -- all the normal LGG and Log controls are allowed. As it says in the manual on page 880:

"When exporting a LUT, any nodes that use Windows or OpenFX will be ignored along with all corrections made within these nodes. All other nodes with Primaries palette and Custom Curves palette adjustments that can be translated into a LUT will have their combined result translated into a LUT. For any nodes that mix supported and unsupported adjustments for LUT export (such as sharpening or blur filtering operations), the unsupported adjustments will simply be ignored."

Basically, no keys, windows, sharpening, or OFX. And that would particularly exclude Color Transform nodes and stuff like that. I try to keep the corrections very simple for exporting LUTs so I get essentially 80% of what I need, then when I get the shot back I apply the rest of what I need for the final.

Yep Marc, that's what I thought to (though it's a good idea to recall the manual lines), thank you for confirming it.
Now, in order to back up or exchange grades, I personally export .drx files anyway and use powergrades, not LUTs.

Thanks for the replies thus far.

I am aware that keys, windows, etc. don't carry over in the LUT. At it's most basic definition, I understand it to be a one to one exchange in values (Take color abc, change to xyz). Again, that's the most boiled down definition, acknowledging that it isn't THAT simple.

That being said, that still doesn't explain why I'm not getting any change in skin tones. The LUT, when applied, should take the same values that I changed in the original grade and apply them to those values in the new clip. Again, color abc to xyz.

[Dwaine Maggart]

I wasn't aware that Resolve .cube LUT's could be used in FCPX?

How are you making the LUT?

I wasn't aware that Resolve .cube LUT's could be used in FCPX?

How are you making the LUT?

Yeah, in one of the more recent updates FCPX added a "Custom LUT" effect. In the past, I had used the "LUT Utility" from Color Grading Central.

I'm generating the LUT just through right-clicking the clip and then selecting "Generate 3D LUT (CUBE)".

[Dwaine Maggart]

Seeing a Project Export drp of the project you generated the LUT from would be helpful.

Seeing a Project Export drp of the project you generated the LUT from would be helpful.

You bet. Link below.

https://we.tl/CD9lu3TC8X

[Dwaine Maggart]

To be clear, you are making a LUT from that 8 node grade?

It has keys and secondary qualifiers in it. It seems a bit too complex to expect a useful LUT out of...

[Peter Chamberlain]

Jordan, considering luts should only have primary grades, your example is not viable.

One thing that never hurts is to export the LUT, then from within Resolve, park on the scene in question. Create a new version, hit "Reset All Grades and Nodes," then import the LUT and apply it to the shot. When you switch back and forth using Previous/Next Version, the shot should be absolutely unchanged. Once you've verified that, you can hand the LUT off to whoever and know it's good. This is pretty standard for VFX workflows.

I wouldn't want to have to do it shot-by-shot with Premiere or Avid or FCPX, but it "theoretically" could be done.

How was the LUT generated? If it was generated in Resolve, what specific controls were used? Be aware that only normal lift/gamma/gain, Contrast, Pivot, Log, Sat, Hue, Curves, and Tint apply -- no keys, no windows, no sharpening.

I would test the workflow with known test signals like SMPTE color bars and a grayscale pattern and see what happens. I would also avoid monitoring within Mac OS and instead use a color-managed output to a calibrated display so that you know what's actually happening to the signal (vs. what the OS does to it).

What about HSL and Qualifier adjustments? Should they be able to be exported through a lut?