I am about to do a new calibration run on my JVC NX7 and just wanted to verify some settings and workflow. I know Steve does not love these projectors, but I have had pretty good results in the past, although it has been over a year since my last calibration.

The NX7 native gamut is close to P3 with green a bit under and red a bit over. The objective is to create a 3D LUT for MadVR in an HTPC (using BMD capture card with VP and eventually moving to JRiver). Sources are UHD blu-ray and Apple TV. Projector will be set to a 2.2 gamma so that MadVR tone maps the PQ curve to SDR 2.2.

Workflow:

• Create BT2020 and DCI-P3 D65 custom colour spaces with 2.2 Gamma.
• Run a cube profile using the custom 2020 space with the custom P3 as subspace to limit patches to P3. Use Legal range.
• Create LUT with custom 2020 2.2 gamma as source to destination NX7 profile using Fit or Peak chroma, normal range. The objective is to correctly map the P3 in the 2020 container of the sources as best as possible to the projector's approximate P3 gamut.
• For MadVR use pass black adjustment on LUT. For JRiver do not adjust LUT

Will this work correctly without the LUT trying to fill in all the unavailable 2020 space? Am I missing anything in the profiling or LUT generation settings?

Thank you !

Hi Andrew,

Instead of using a P3 subspace, it might be an interesting experiment to extract the native space of the projector, modify the white point to D65, and target that as the subspace. Seems to me like you'd get the best result LUT wise there as it is targeting itself.

: )

Let us know how it goes!

Take care,

Jonathon

If you 'calibrate' to an extracted colour space you are not calibrating to a standard, so the result would be inaccurate.
What you can do is use a Reduced Gamut patch set to calibrate to the target P3 colour space, based on the projector not covering P3 fully.
https://lightillusion.com/advanced_operation.html#reduced-gamut

Steve

madVR will need a P3D65 gamma 2.2, modify the 'DCI P3 D65' and change the gamma from 2.6 -> 2.2, then save with a different name.

You can use any Gamma (EOTF) you want with madVR Envy & Core.
Just remember to set the correct value in the 'Settings' tab in the ColourSpace Envy menu.
If that is not set, Envy will assume a 2.2 EOTF, regardless what EOTF the LUT was actually generated for.

Steve

I assume that for creating the technical LUT to be used to generate the patch set, I can just extract the native projector Gamut by Extract Space from a 100% gamut sweep profile, adjusting the gamma to 2.2 and the white point to D65?


I pre-calibrate the projector with a 1D LUT at 2.2 gamma. I am not using an Envy but a HTPC with a BMD capture card, VideoProcessor software and MadVr renderer.


The question I have, should the final LUT not be created using UHD 2020 with 2.2 Gamma space, as the source is UHD 2020 from a Blu-ray that was probably mastered with P3 primaries but is contained in 2020? Would not creating the LUT for P3 D65 be inaccurate with these sources?


Thanks Jonathon. Always appreciate your input.

madVR is remapping the content and expects to have a calibrated projector with P3D65 color space and a gamma setting of 2.2.