Hello,

I'm using ColourSpace for the first time and I want to calibrate the HDR PQ mode of my Dell UP 3221Q monitor by following this guide: https://lightillusion.com/dell_manual.html

I can connect to the monitor, but when uploading the Unity Bypass LUT to the monitor (with 3D + 1D and CAL 1 or CAL 2 selected), I get this error message:
Error: Failed to GetCalBlockLength(CALBLOCK_PRE_LUT)

Unfortunately, ColourSpace has blocked the OSD of my monitor and the power button. Even after pulling the power cord, the OSD is still deactivated. The monitor was in mode H1. Do I need to configure one of the three user modes instead?

The Dell User Guide does say "Note: Only CAL 1 and CAL 2 slots can be calibrated."
If you continue to have issues, I have that Dell monitor here, so I can fire it up to do some tests.

Steve

Did you sort the issues?

Steve

I'm now able to upload LUTs to the monitor. I did this:

• Unlocked the OSD with "Dell Color Management" application
• Disconnected my DisplayPort cable (only 1 HDMI connection and the USB cable left)
• Reset Color of CAL1 and CAL2 in the OSD of the monitor

Unfortunately, I can only achieve a maximum of 580 nits with the Unity Bypass LUT uploaded (brightness slider within ColorSpace at 1023). Therefore, I am trying to calibrate the monitor via a 3D LUT in DaVinci Resolve instead.

My current problem is that the generated LUT looks messy propably due to the many points at the gamut edge (see attached file). I will try Reduced Gamut Profiling next (https://lightillusion.com/advanced_reduced_gamut.html).

Generated LUT (source gamut: ST2084 1000 nits)

That looks more like an Extra Delay issue?
Or as a FALD display, did you use an incorrect patch size?
(But it is impossible to tell from a screen grab of the LUT. Post the actual profile.)
What TPG are you using?

Steve

I've set the extra delay to 0.5 seconds. (The monitor is sometimes slow if my eyes don't fool me.)


I used L20 and have since increased it to L32. Above L32 the monitor is not stable. I use the TPG within DaVinci Resolve via a Decklink card. (I still have a PGenerator and HDFury Linker lying around.)

I've attached two profiles. This time, I had no luck even with the "Reduced Gamut Profiling" method. I noticed that the points are somehow compressed in the corners with lower resolution around the neutral axis. Is that normal?

Attached file: Dell 3221Q H1 characterizati.zip

Any FALD display should really be profiled with full screen patches.

And the monitors is already pre-set to a PQ HDR EOTF and a (really bad) Rec2020 pre-calibration.
That means the Unity/Bypass upload has not been performed, or you are not using a Cal slot, which you have already stated above.

So you will need a Reduced Gamut approach, but the patch set you used was not reduced gamut enough.
The LUT result from the Reduced Gamut profiling shows it is close, but not correct enough.
You can see thins by looking at the profile via the volumetric graphs, such as the below cube view.
The long tangent lines show the patches are outside the display's actual gamut capability.
And if your license level supports it, you could also use Custom Filters to remove those measurements form the profile.

But I would look into why you cannot reach 950 nits with a Cal slot.
That doesn't make sense.

Steve

Gamut Error

Success! I just measured over 1300 nits in CAL2.

If others are also having difficulties, here is my solution:

• Open the "Display Info" menu and make sure that the HDR Source item is "Active". In my case it wasn't enough to have HDR metadata enabled in DaVinci Resolve. Switching between 10-bit and 12-bit helped to convince the monitor.
• Open the Color menu, select CAL1 or CAL2 and hit "Reset Color" (Once again, if you already did before. The order was crucial in my case.)

I'm still on a trial license. Custom Filters sounds nice but if all goes well, I will not need them for the Dell monitor, right?

One more thing isn't clear to me: When calibrating the Dell monitor, is only a 3D LUT uploaded, or a combination of a 3D LUT and a 1D LUT for the EOTF? I'm a little worried that there might be precision issues without a higher license.

You will ned to follow the Dell User Guide, as Dell monitors have a very different approach to calibration, with a fixed grey scale.
All is explained in the User Guide.
And no, this is not a ColourSpace license level issue.

Steve