Error with video card gamma tables

[Ben Neufeld]

I’m new to calibration and to using this software.  I am trying to calibrate a Dell U2711b connected to an iMac (late 2012, 10.11.6) through a Blackmagic Ultrastudio Mini Monitor, using an X-rite i1 Pro.

I am following the 3D Lut Creation Workflow for Resolve (https://hub.displaycal.net/wiki/3d-lut-creation-workflow-for-resolve/) and have run the software several times, always with the same error at the end– saying

The display’s video card gamma tables 1D LUT calibration is non-linear, but the 3D LUT contains applied 1D LUT calibration.  Make sure to manually reset the video card gamma tables to linear before using the 3D LUT, or createa  3D LUT without calibration applied to do the latter, enable “Show advanced options” in the “Options” menu and disable “Apply calibration (vcgt)” as well as “Create 3D LUT after profiling” in the 3D LUT settings, then create a new 3D LUT).

I assume that the video card being utilized is the Ultrastudio, however I don’t know how I would reset its gamma tables to linear.   But if the video card being utilized is the iMac’s, I also can’t figure out how to reset its video card’s gamma tables to linear.  I have tried changing its display profile to a generic Apple RGB profile, but have gotten the same error.

I have tried disabling “apply calibration (vcgt)” and “Create 3D LUT after profiling”, however I realized that the LUT that this creates doesn’t do anything, so I’m not sure why this workaround would be useful.

Can anyone point me in the right direction for dealing with this error and getting a proper calibration through my set up in Resolve?  It would be immensely appreciated.  Please let me know if there’s any other information that I should have provided.

[Florian Höch]

Hi,

I am following the 3D Lut Creation Workflow for Resolve (https://hub.displaycal.net/wiki/3d-lut-creation-workflow-for-resolve/) and have run the software several times, always with the same error at the end– saying

The display’s video card gamma tables 1D LUT calibration is non-linear, but the 3D LUT contains applied 1D LUT calibration.  Make sure to manually reset the video card gamma tables to linear before using the 3D LUT, or createa  3D LUT without calibration applied to do the latter, enable “Show advanced options” in the “Options” menu and disable “Apply calibration (vcgt)” as well as “Create 3D LUT after profiling” in the 3D LUT settings, then create a new 3D LUT).

Note that this is not an error, just a warning – as you’re going to use the 3D LUT with a monitor connected to the Ultrastudio Mini, you’re not affected by the videoLUT, so you can safely ignore the warning.

I have tried disabling “apply calibration (vcgt)” and “Create 3D LUT after profiling”, however I realized that the LUT that this creates doesn’t do anything, so I’m not sure why this workaround would be useful.

Disabling “apply calibration (vcgt)” creates a 3D LUT where any 1D calibration needs to be applied in another way, e.g. by installing the display profile and letting the OS (in case of Mac OS X) or the DisplayCAL profile loader (under Windows) take care of it. The 3D LUT will still do something, but without the 1D calibration in place somewhere along the chain it won’t be correct (only if the calibration was linear to begin with, which is the case for the 3D LUT presets in DisplayCAL, but this is a detail). Usually you should create a 3D LUT with calibration applied (wether linear or not doesn’t matter), because Resolve will apply the 3D LUT and there’s no videoLUT over the Mini Monitor.

I hope this makes things a little clearer.

[David Steinberger]

HI, I’m also trying to create a 3D LUT for Resolve. Have been using DisplayCAL so far only for photo (C1) but have to do some video now and therefore wanted to create a 3D LUT for Resolve. I’m confused:

Usually you should create a 3D LUT with calibration applied (wether linear or not doesn’t matter), because Resolve will apply the 3D LUT

I’m on  MBP and guess there is no way to reset the video gamma table to linear, isn’t it? In that case, shouldn’t I create the 3D LUT w/o Apply Calibration and just load my display profile previously generated by DisplayCAL?

I really appreciate any help on this!

• This reply was modified 7 years ago by David Steinberger.

[Florian Höch]

I’m on MBP and guess there is no way to reset the video gamma table to linear, isn’t it?

Only by using a display profile with linear calibration.

In that case, shouldn’t I create the 3D LUT w/o Apply Calibration and just load my display profile previously generated by DisplayCAL?

Correct.

[Ben Neufeld]

Thank you for your earlier response Florian, much clearer.

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