LUT example 2.zip (18.4 MB)
Hi this has some example images along with the original LUT, a CLF with the colorspace transforms baked in to the LUT, and a clf with colorspace transforms perform as operations inside the CLF.
Thanks for the example, but I think I need more data to understand what is going wrong. Can you share also the image you give as input to resolve, and describe the steps you apply in there?
Thanks!
FWIW I just tried with Natron and I get the same result as in ART. So, I think you must be doing something different/additional in Resolveā¦
I think lightroom applies a tone curve before the LUT. I donāt know exactly what curve, but adding something S-shaped in the CLF before the 3dLUT application seems to go in the right direction. Hereās an updated LUT if you want to try it.
ht.clf.zip (423.9 KB)
Okay, so:
Iāve uploaded everything to a G-drive as the file sizes are a little large. I hope thatās okay:
https://drive.google.com/drive/folders/1yCknw4ih7mLoHnuyXWCF1jM2mG7Ip8Nf?usp=share_link
Applying Hue Twist LUT in Lightroom closely matches applying either the CUBE (Designed for Prophoto/1.8) or CLF version (designed for AP0/Linear) of the LUT in Resolve. The image Iām using as input for Resolve is a TIFF exported from ART (Exported with a working profile of ACESAP0 and an output profile of ACES2065-1 ICC V4).
In ART Iām using the same DCP (Cobalt Standard) and tone curve that I believe Lightroom is using (Iāve also uploaded these to the G-Drive link).
Initially I thought something similar - that maybe Lightroom was applying a tone curve before the LUT, but it doesnāt explain why Iām seeing the LUT work how I expect it to when applied in Resolve to the exported ART image.
In ART when applying the LUT, Iām doing so in the film sim section, as this matches the behaviour of Lightroom/Applying The LUT at the very end of the pipeline?
Thank you so much for your help! Iāve been loving ART so far and appreciate your help 
Ryan
Thanks for the examples. I can confirm that the mismatch is due to the application of the tone curve before the film simulation, which is what ART does by default. Luckily, we can change that: thereās a hidden parameter in the FilmSim tool that lets you apply the simulation after the tone curve. To make it visible, you can load the attached .arp profile (or if you want to make it always available, just add the .arp to your default processing profile, e.g. by using the dynamic profile editor). Then, just check āapply after tone curveā and it should work. Little video demo:
filmsim-at-end.arp (64 Bytes)
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Epic, this did it! Thank you so much. Thereās no way I ever wouldāve figured this out 
Is there a place where hidden settings are documented? Iād love to learn more.
Sorry Iām tired but how does the tick box change it or are you saying uncheck it?? I thought the pipeline had the tone curve before filmsim and the checkbox says to also use that orderā¦ maybe Iāll read it again tomorrowš
Sorry, my bad. The default is tone curve after film sim, not before
In general hidden settings are considered ādeprecatedā, thatās why they are not really documented (and they are not that many). But deprecated just means āyou should know what you are doingā, which is exactly the case here.
Sorry I only asked because here I looked and the tone curve seemed to come before as you said and not after so I was just a bit confused but I often amā¦
I think this is where some of my confusion stemmed from as well. Tone curve is documented as coming before Film Sim in the pipeline.
I feel like this checkbox should be enabled by default, with the default setting being āApply after Tone Curveā as to not too closely mimic LUT usage in the āColor/Tone Correctionā panel?
The order was changed at some point, but I forgot to update the docs ā sorry about that!
I still think that in most cases having the tone curve after the film sim is more useful, but I concede there might be different points of view. If you want a tone curve before, you can either use the checkbox or use a CTL script (thereās one in the ART-ctlscripts repoā¦)
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All good! Very keen to test the CTL scripts over the weekend. And super cool to see a Tetra HSL and density module available there!
Just to confirm, does this mean that a tone curve CTL can be loaded into the āColor/Tone Correctorā after a LUT?
Did you see thisā¦you might be interestedā¦
Basically John is doing a sequence of steps within the Color/Tone Correction module for his film simulation including adding a tonemapperā¦
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Yes. You can also just add a tone curve in ācolor / tone correctionā, and keep using āfilm simulationā to apply the lut.
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No, but thatās really cool. Will check it out!
Iām pretty stoked -
Having a rearrangeable/modular photo editor that doesnāt rely on a library is what Iāve wanted forever and didnāt know existed 