3D Lut Verification

[anonymous SourceForge]

Hello,

I’m using the 3D Lut created by DispcalGUI as a calibration LUT in Speedgrade. I need to verify the 3D Lut. Is there a way to do this directly in Speedgrade, or could I enable my 3D Lut in Windows and then run the verification in DispcalGUI?

Many thanks
Jeremy

[Florian Höch]

Hi,

I need to verify the 3D Lut. Is there a way to do this directly in Speedgrade, or could I enable my 3D Lut in Windows and then run the verification in DispcalGUI?

It depends on what options you have in Speedgrade (don’t have it unfortunately so I’m not able to tell).

Generally you’ll set up the verification with the same settings for source profile and tone curve as during 3D LUT creation (in DCG 3.0 the verification settings will already be set correctly after creating a 3D LUT).

If Speedgrade doesn’t have the ability to display patches through the 3D LUT, you’d set “Devicelink profile” to the profile with the same basename as the 3D LUT (the profile is always created alongside 3D LUTs).

• This reply was modified on 2015-05-18 11:00:36 by fhoech.

[anonymous SourceForge]

Thanks a lot. Ok I understand the verification process. As for Speedgrade, I know I can apply a calibration 3D Lut to my project before grading. What do you mean by “display patches through the 3D Lut”? In Speedgrade? You mean DCG could display the patches inside the software and take its measurement from there?

[Florian Höch]

You mean DCG could display the patches inside the software and take its measurement from there?

Not directly, but there are ways to do it. See Setting up unthethered “Auto” mode in the wiki.

[anonymous SourceForge]

Ok I get it! Didn’t know I could do that, it sounds like the best way to go about it.

Now I usually double check calibration using different softs but my equipment only allows me to use a software LUT. Is there a way to enable the 3D Lut created by DCG so that other apps will run their color tests through the DCG LUT?

[Florian Höch]

Is there a way to enable the 3D Lut created by DCG so that other apps will run their color tests through the DCG LUT?

Unless the software supports it, the only other option I can think of is a hardware LUT box.

[anonymous SourceForge]

Thanks, I will check if other apps can do that. At the moment I’m leaving DCG open after calibration with the “Preview calibration” box ticked, and running the test from another app in the same time, but I’m not sure this technique is accurate

[Florian Höch]

At the moment I’m leaving DCG open after calibration with the “Preview calibration” box ticked, and running the test from another app in the same time, but I’m not sure this technique is accurate

The 1D LUT calibration will be active (grayscale/whitepoint), but not the 3D LUT (gamut correction).

[anonymous SourceForge]

Ok I see. That helps a lot! Thanks

[anonymous SourceForge]

I’m struggling with 3DLut verification. How is it than when I click Measurement report at the end of calibration, it starts displaying patches again? Isn’t DCG verifying the profile directly after calibration and should give me a report?

Also, is there a way to import and verify a software 3D Lut inside DCG, without launching the whole profile & calibrate process?

[Florian Höch]

I’m struggling with 3DLut verification. How is it than when I click Measurement report at the end of calibration, it starts displaying patches again?

To verify a 3D LUT, some verification measurements need to be made. These must be different from the profiling measurements.

Isn’t DCG verifying the profile directly after calibration and should give me a report?

Not automatically, no. The dE numbers seen in the dialog directly after calibrating/profiling is the profile self check, it tells you the fit error of the profile to the profiling measurements. Numbers in the ballpark of < 1 dE average and < 5 dE peak are usually ok. Typically you’ll get numbers of < .5 dE average and < 3 dE peak for a reasonably accurate profile.

Also, is there a way to import and verify a software 3D Lut inside DCG, without launching the whole profile & calibrate process?

No way and no need to import the 3D LUT, you just need to make sure that it’s active in whichever software you’re using, and then do the verification measurements. E.g. for Speedgrade, this could involve exporting test patches of the verification testchart as image files like outlined in the wiki page I linked, setting “Display” in DCG to “Unthethered”, making sure verification settings match the ones used during 3D LUT creation, then starting the measurements with the first patch displayed in Speedgrade and starting playback to measure them one after another.

[anonymous SourceForge]

Okay I get it, will try that. Thank you for your quick and detailed answers.
At the moment I have E*76: average 0.82, maximum 6.67, RMS 0.94.

Now those are numbers for the newly created profile, correct? Is there a way to verify the current calibration of my monitor in DCG?

[Florian Höch]

At the moment I have E*76: average 0.82, maximum 6.67, RMS 0.94.

Hmm, seems higher than I would expect for a LUT-based profile, but could still be ok.

Now those are numbers for the newly created profile, correct?

Yes.

Is there a way to verify the current calibration of my monitor in DCG?

Only if it’s ICC-v2-based. Set “Settings” to “Current” and make sure a profile is assigned to the display in the OS color settings.

[anonymous SourceForge]

Ok. It’s an EIZO CS240 that I have internally calibrated using ColorNavigator (which I believe applies an ICC inside the monitor)

[Florian Höch]

Should work. E.g. if the monitor is calibrated to AdobeRGB, assign the AdobeRGB profile in OS color settings to the display.

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