3D LUT create from both matrix and LUT profile ICC is same result/accuracy?

[Prapan Chulapinyo]

I’ve read wiki of “3D LUT creation workflow for Resolve” and have some question.

You can create additional 3D LUTs from any existing profile selected under “Settings” by going to the “3D LUT” tab and disabling “Create 3D LUT after profiling”. The button at the bottom will change to “Create 3D LUT…”. You can now adjust the 3D LUT settings and create as many additional LUTs as you like.

Say I already have Single curve + matrix for everyday use and XYZ LUT + matrix for someday need accuracy.

From instruction in wiki, I have a 3D LUT .cube file along with new addition ICC profile. That need to use together right?

So if I can create addition 3D LUT from any existing profile – question is : 3D LUT create from ‘Single curve + matrix’ or ‘XYZ LUT + matrix’ create same result/accuracy? I guess 3D LUT it depend on their own not depend on ICC profile but I’m sure. Why I ask, so that I’ll create 3D LUT from maybe Single curve + matrix that I use everyday no need to have additional 3rd profile just for the 3D LUT only. And if the result/accuracy is same then I will need only a 3D LUT from Single curve + matrix that I often use than from XYZ LUT + matrix.

[Vincent]

I’ve read wiki of “3D LUT creation workflow for Resolve” and have some question.

You can create additional 3D LUTs from any existing profile selected under “Settings” by going to the “3D LUT” tab and disabling “Create 3D LUT after profiling”. The button at the bottom will change to “Create 3D LUT…”. You can now adjust the 3D LUT settings and create as many additional LUTs as you like.

Say I already have Single curve + matrix for everyday use and XYZ LUT + matrix for someday need accuracy.

From instruction in wiki, I have a 3D LUT .cube file along with new addition ICC profile. That need to use together right?

So if I can create addition 3D LUT from any existing profile – question is : 3D LUT create from ‘Single curve + matrix’ or ‘XYZ LUT + matrix’ create same result/accuracy?

No.

I guess 3D LUT it depend on their own not depend on ICC profile but I’m sure.

LUT3D is a “frozen” transformation between a colospace (like Rec709) and another (display ICC)… so it is dependent on pofiles used to make them.
With a destination matrix profile, almost all nodes in LUT3D will be calculated from a supposed idealized display response.
With an XYZLUT, although there will be some interpolation, they will be dependent on actual display response (captured in XYZLUT inside ICC).

It’s like a suit. You can buy a standard M/L/XL/XXL size (~matrix) or some taylor can measure your upper body with a laser to build a 3D mesh (/joke) and make a full customized suit.

Why I ask, so that I’ll create 3D LUT from maybe Single curve + matrix that I use everyday no need to have additional 3rd profile just for the 3D LUT only. And if the result/accuracy is same then I will need only a 3D LUT from Single curve + matrix that I often use than from XYZ LUT + matrix.

It won’t be so accurate… but it depends on how good is your display (how a simple 1trc+matrix profile describes actual monitor behavior).

Remember to unload GPU calibration on system wide calibration (ICC), unless both matrix and XYZlut profiles share the same calibration curves and for LUT3D (from XYZLUT profile) you unchecked to use VCGT.

[Prapan Chulapinyo]

LUT3D is a “frozen” transformation between a colospace (like Rec709) and another (display ICC)… so it is dependent on pofiles used to make them.

So which profile I build 3D LUT from, I must use those 3D LUT with that profile then correct?

With a destination matrix profile, almost all nodes in LUT3D will be calculated from a supposed idealized display response.
With an XYZLUT, although there will be some interpolation, they will be dependent on actual display response (captured in XYZLUT inside ICC).

It’s like a suit. You can buy a standard M/L/XL/XXL size (~matrix) or some taylor can measure your upper body with a laser to build a 3D mesh (/joke) and make a full customized suit.

Oh I get it. So if 3D LUT  with XYZ LUT profile should be more accurate than matrix then. But with cost of some less smooth/more banding than matrix right?

It won’t be so accurate… but it depends on how good is your display (how a simple 1trc+matrix profile describes actual monitor behavior).

So meaning with LUT should be more accurate than matrix then.

Remember to unload GPU calibration on system wide calibration (ICC), unless both matrix and XYZlut profiles share the same calibration curves and for LUT3D (from XYZLUT profile) you unchecked to use VCGT.

This one I confuse. Wiki say :

The “Resolve” preset is set up to not use iterative gray balance calibration, but as we are going to create a profile that will also be installed to the operating system, you may want to enable it. Set calibration tone curve on the “Calibration” tab from “As measured” to “Rec. 1886” (or another desired curve). Note that this setting does not influence the 3D LUT tone curve, which you can adjust in the next step.
IMPORTANT If you have opted to do iterative gray balance calibration, enable advanced options in the “Options” menu, then go to the “3D LUT” tab and disable “Apply calibration (vcgt)”.

I did set tone curve in matrix and LUT profile to “gamma 2.2” and for the 3D LUT profile I set tone curve to “Rec. 1886”. But I also go to the “3D LUT” tab and disable “Apply calibration (vcgt)”. Do I need to unload GPU calibration on system wide calibration too?

[Vincent]

I wrote the answers you seek before:

Remember to unload GPU calibration on system wide calibration (ICC), unless both matrix and XYZlut profiles share the same calibration curves and for LUT3D (from XYZLUT profile) you unchecked to use VCGT.

DisplayCAL LUT loader (win) or other 3rd party or OS loaders load grey calibration (calibration curves, VCGT) into GPU, so if you set a custom ICC as display profile, whole grey ramp calibration is loaded system wide.
Depending on GPU this may cause banding, since it is HW or vendro driver dependent these issues are not related to DisplayCAL.

So *if you wish to keep system wide grey calibration* (default ICC profile assigned to display in OS color management configuration) you have to choose what to do with grey calibration in LUT3D:
-assume that there will be a system wide loader (LUT3D without VCGT), keep custom ICC calibration
-unload system wide calibration and make LUT3D correct grey color (apply VCGT)
Choose only one.

madVR software which used LUT3D too (in its own format) automatically unloads & lock GPU calibration while its LUT3D is active, and restores it upon closing (this behavior can be configured to something else). So user usually  does not have to choose, creates LUT3D with VCGT and by default madVR unload/load grey calibration.

AFAIK Resolve does not do that, you you have to choose in advance.
On a general puprose computer (Adobe suite, browsing, and also Resolve too) *I* find more useful/easier to keep system wide grey calibration (VCGT loaded by displayCAL loader) active and make resolve LUT3D ***for GUI*** without VCGT. YMMV.

[Prapan Chulapinyo]

Thank. I got it now. Then I will keep Single curve + matrix and XYZLUT and then make 3DLUT frome those without VCGT. I think I will use 3DLUT from XYZLUT more often then.

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