The factory LUTs are not null LUTs. They cannot be because the native panel gamma is not rec.709. What I was hoping to do was to download the LG C9 factory LUT for the most color accurate factory mode (which is Expert Dark) and use that to replace the defective near-black values of my i1Display profile LUTs.
I had the impression from my reading that using DeviceControl one could "backup" the 3dLUT in the C9, but I cannot find a description of how to do that and I can see no download button for the 3dLUT in the DeviceControl LG 2019 Template Rev.5.
There is no "Factory 3D LUT" to download.
Native panel gamma
is 2.2. Native panel gamut
is close to DCI P3 (without the white sub pixel boost desaturating the colour volume). When the TV receives Rec709 input signaling it uses a colour gamut mapping matrix to output SDR Rec709.
When you press "Reset 3D LUT" all you are doing is preparing the TV by locking its user menu gamut selection to Wide (native) and uploading a Null LUT to replace any previously uploaded custom 3D LUT, you are not
resetting a factory 3D LUT. When you press "Restore Factory Values" you are preparing the TV by telling it to bypass that colour gamut mapping matrix.
You can easily see this in action by only Resetting the 3D LUT (do not press restore factory values) and then uploading a user generated Rec709 3D LUT. You will see double mapping to Rec709, thus shrinking the overall gamut coverage.
See this below link for an example of this (with images). https://www.avsforum.com/threads/lg-oleds-3d-lut-profiling-using-lightspace-thread.3043520/post-60015137
Never has it been claimed that you can "backup and/or restore" factory 1D and/or 3D LUTs using Device Control Templates. What you can do is store user generated 1D/3D LUTs and upload them at any time, which is a huge time saver should an issue arise where you need to factory reset your TV for some reason.
way to restore full factory calibration is to perform a full factory reset. No software has access to "download" the factory calibration.
What patch sequence are you using that is causing these "defective near-black values of my i1Display profile LUTs".
If you are using the sequences provided with the guides and you are targeting a peak white of 100 nits at 100% white (approx 124 nits @109%) there are only 6 points within that sequence that should measure below the X-Rite rated accuracy threshold of 0.1 nits (excluding black).
Out of these 6 points, 3 of them compare favourably and within allowable tolerance when compared to a Klein K10-A. As you go below 0.05 nits it will start to deviate further, but there are only 3 points below that range within the patch sequence. Below 0.03 nits is where the i1 Display Pro becomes unreliable.
The image above is that exact patch sequence (with target xyY) but sorted in order of target luminance based on the Rec709 Target Gamut with a Gamma of 2.4 and peak 109% of 123.3358 nits. However, when you are profiling the display it will be in native 2.2 gamma and native gamut so should actually measure brighter than the values shown above (and obviously not hitting its Rec709 target xy either).
It is part of the reason this patch sequence is recommended for LG OLED. You can delete those points if you are concerned, you can see the patch number in the sequence to the left of the image.
You should realise that with LG OLED there is a dithering algorithm at extremely low luminance output levels. It is slightly different on the 2019/2020 LG OLEDs when compared to the 2018, but it makes extremely low luminance output levels very difficult to measure even with the most expensive (what is considered "reference") meters. Instead of trying to manually manipulate a LUT, you may be better off attempting to generate a LUT to a slightly lower gamma value, I have found a value of 2.35 to work well on troublesome panels that struggle to come out of black properly.
Or, you could try Parametric Gammahttps://www.lightspace.lightillusion.com/parametric_gamma.html