how do I build ICC profile with 3D lut for my NEC?

[Tony]

Hello Florian!

I have always used the defaults with good results. I just purchased a used NEC P241 and it allows me to upload 3D ICC print profiles into the hardware lut.

Does Displaycal support this? If yes, how do I set it up to do it?

When build a display profile using the defaults does it already include the 3D info and the video card only used the 1D?

it would be great if you can tell me how to make an ICC profile with a 25*3 LUT or tell me another way to convert a madvr lut into a printer style profile

Thanks,

Tony

[Florian Höch]

Hi,

I just purchased a used NEC P241 and it allows me to upload 3D ICC print profiles into the hardware lut.

What kind of profiles/3D LUTs does it support? Device link profiles? “Regular” device profiles? Why would it be limited to print (if that’s even the case)?

[Tony]

The instructions don’t really say specifically. What I know for sure is that this is how it was meant to be used:

1. If you have an aRGB monitor, you can apply a srgb profile and it will reduce the gamut to for web viewing
2. If you have an aRGB monitor and you want to simulate prepress or an inkjet printer it can do that in hardware like Photoshop does in software. It will do split screen so you can see on the left aRGB and on the right toggle offset press/web/inkjet

These 2 ways is what the monitor lut was designed for.

Light Illusion has a way to use the LUT hardware for video grading
http://www.lightillusion.com/nec_manual.html
summary:
a.) upload null cube – which I can do and is the same as “native” on my NEC
b.) Calibrate
c.) Upload file

1. I tried the device link and it won’t recognize it.
2. I can however upload any printer lut including ones with 2000 patches  and see the individual patches.

Any guess at where to start testing would be appreciated

Regards,

Tony

[Florian Höch]

So it seems the NEC supports (Iridas) .cube 3D LUTs. So far, so good. You can use DisplayCAL to create such LUTs, but it cannot directly upload them to the monitor (I assume NEC provides an utility to do this?):

1. Profile the display like you normally would. DO NOT install the profile.
2. Open the standalone 3D LUT maker.
3. Set the source profile as desired, e.g. sRGB.
4. Set tone curve to “Apply black output offset (100%)”.
5. Make sure target profile is set to the profile you created in step 1.
6. Set rendering intent to “absolute colorimetric with whitepoint scaling” if the display whitepoint is different from the source profile whitepoint, otherwise “relative colorimetric”.
7. Set 3D LUT encoding and format to full range RGB, IRIDAS (.cube).
8. Create the 3D LUT and upload it to the monitor using whichever utility NEC provides for this purpose.
9. Assign sRGB to the monitor.

[Tony]

Hi Florian,

How did you know that NEC supports (Iridas) .cube 3D LUTs?

I followed your instruction exactly and after I ran the 3D lut creator I get 2 files, a linked ICC profiles that NEC doesn’t recognize and a .cube file. The NEC software only allows ICC files to be uploaded to the monitor.

http://www.necdisplay.com/support-and-services/multi-profiler/downloads
Let me know if you have any ideas!

Thanks,

Tony

[Florian Höch]

How did you know that NEC supports (Iridas) .cube 3D LUTs?

You posted it above, but maybe I misunderstood you.

The NEC software only allows ICC files to be uploaded to the monitor.

That’s not technically the case – it’s not a print profile that gets upload to the monitor. From what I gather from the MultiProfiler manual, the 3D LUT is created on the fly before uploading, and only print profiles are supported as emulation target, like you mentioned initially. According to the manual, the 3D LUT maps from whichever display gamut is selected in MultiProfiler, to the selected print profile, and then to the native display gamut, so no surprises there.

[Tony]

If Leave the monitor at native (green cast) and run displaycal and upload the monitor profile it will still have the green cast but the colours will shift slightly so I thought it was not working. It seems like the greyscale is ignored.

NEC has 2 software  Spectraview and Multiprofiler. Here is my procedure to get it to work.

1. Use Spectraview to set Primary coordinates

2. Use Spectraview to calibrate greyscale and gamma – monitor looks quite good but not perfect. There is no way to access the 1d LUT without Spectraview or other paid software.

3. Use Displaycal to generate color profile

4.  Upload color profile to NEC using multiprofiler.

Colors are almost perfect!

[Eric]

It appears that Multiprofiler can also generate (and program) the 3D LUT from a display ICC profile:

http://cdn-docs.av-iq.com/other//ICC_ProfileEmulation_Technology_Paper_Print.pdf

So it appears that the right way to do it is to first calibrate the NEC monitor to Native (Full) using Spectraview, profile the calibration using DisplayCAL (installing the ICC profile afterwards), then feed sRGB IEC61966-2.1 into Multiprofiler to generate the sRGB (3D LUT-based) preset.

I haven’t tried this yet; will note down my findings here once done.

[Eric]

Unfortunately, it seems that Multiprofiler only uses factory measurements to emulate the target profile. Since the monitor’s color characteristics would have changed much already by now (assuming an old monitor), accurate emulation cannot be achieved despite precise 3D LUT capability.

In the Multiprofiler’s user’s manual it is hinted that the currently installed ICC profile (for example, a very accurate one generated using DisplayCAL) is considered during 3D LUT calculation/generation, but it doesn’t seem to be the case.

Will try using the trial version of Basiccolor Display 5 since it supports 3D LUT programming. Then compare Spectraview vs 3D LUT results using DisplayCAL. Maybe 3D LUTs aren’t really that much useful after all as Spectraview’s FAQ suggests:

Why doesn’t SpectraView offer an option to make full 3D LUT type ICC/ColorSync profiles in addition to the current shaper/matrix profiles?

The LCD panels used in the SpectraView displays have excellent color linearity characteristics and can be characterized using the much simpler shaper/matrix profiles. Accurate 3D LUT profiles require a minimum of around one hundred measurements (and up to several hundred) to generate the necessary data and offer very little advantage despite the large increase in measurement time. Additionally there are some compatibility issues with various software applications when using 3D LUT type display profiles.

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