About creating LUTs for matching monitors…

[Rodrigo Silvestri]

Hi. I’m trying to profile two monitors and then create a LUT to match one of them (HP Z27X gen1) to the other (Sony BVM-L230), and I am having some questions and some trouble about profiling for creating 3D LUTs.

1.a- In most cases I define brightness and whitepoint before DisplayCal (usually with HCFR) based on the ambient light or backlight (I try to find a neutral D65 backlight and then manually/visually match the monitor’s RGB to the backlight, trying to keep it below 10dE from D65). Can I simply turn off the Interactive Display Adjustment in the Calibration tab?

1.b- If I disable this, DCal asks me if I want to use linear calibration curves. I assume I do have to use linear calibration curves in this case, right?

2.- I’m trying to match the Z27X to the Sony. They have visually the same whitepoint and brightness level, but blacks on the HP are a bit brighter than on the Sony. Which would be the right tone curve setting to not have any crushed blacks? I intend to have both displays showing  the whole signal without clipping, and have the most similar color result with a slight difference in contrast due to the black levels.

3.- I profiled both displays with the same meter and same DCal version but in different computers/systems, profiled one then copied the profile to the other computer and used the same settings to profile the HP display. Now I’m in the 3D LUT Maker, selecting the Sony as source profile and the HP as destination profile, and I’m getting “Error  – BT.1886/Abs power mode only works with an RGB matrix input profile” when trying to adjust the gamma settings. Is it possible to use another display’s profile while adjusting the gamma/tone curve? The result I’m getting with unmodified curve has a much brighter gray, different gamma.

Thanks!
Rodrigo

[Florian Höch]

Hi,

In most cases I define brightness and whitepoint before DisplayCal […] Can I simply turn off the Interactive Display Adjustment in the Calibration tab?

Yes.

1.b- If I disable this, DCal asks me if I want to use linear calibration curves. I assume I do have to use linear calibration curves in this case, right?

Yes, 1D calibration is not used by default in any of the 3D LUT presets.

2.- I’m trying to match the Z27X to the Sony. They have visually the same whitepoint and brightness level, but blacks on the HP are a bit brighter than on the Sony. […]

My recommendation would be to set both to the same black level (i.e. in this case, raise the Sony black level until it matches the HP). If you cannot raise the black level using display controls, you can do so via calibration (set a black level target that both screens can achieve, use default gamma 2.2 100% output offset curve for calibration, or sRGB curve – doesn’t really matter, as it will be overridden by the 3D LUT target anyway). 3D LUT target should be gamma 2.2-2.4, 100% output offset.

3.- 3D LUT Maker, selecting the Sony as source profile and the HP as destination profile

That’s incorrect. Source is always Rec. 709 for a Rec. 709 3D LUT. Destination is the respective display profile.

[Rodrigo Silvestri]

Great, thanks!

And what about this screen? Which is the right selection if I’m just using a previous setting to create a new LUT for a new monitor?

Thanks!
R.

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[Florian Höch]

With regards to the screenshot, the shown choice(s) are the correct ones (linear, don’t use other screen’s calibration).

[Rodrigo Silvestri]

Thanks!

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