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Display Calibration Light Illusion Forums / Display Calibration /

LUT Generation (Eizo CG247X + Lightspace)

Author isticism
#1 | Posted: 19 Nov 2018 20:35 
A real beginner question for someone on my first calibration attempt with the 3 day license of LightSpace: How do you generate a calibration LUT?

The Eizo guide details how to do a quick profile, which I successfully executed, and then says:
"After profiling a Calibration LUT can be generated as normal, and with the LUT held within LightSpace navigate back to the 'Upload' menu, and with the 'NULL Cube' tick box un-ticked, the present LUT displayed within LightSpace can be 'Uploaded'."

How the LUT is to be generated is not explained, nor can I find it in the user manual? When I return back to the upload dialog after quick profile, I am unable to "un-tick" the NULL cube box and it does not appear that any LUT is being "held within Lightspace"? How do I generate a LUT?

Any help is much appreciated, thanks!

Author RollsRoyce
#2 | Posted: 19 Nov 2018 20:58 
Use Tools > Colour Space > Convert Colour Space. "Source" will be the color space used by the content, such as "Rec. 709" for HD SDR content. "Target" will be the profile you created from your monitor. You'll assign a name to the LUT, then click "Create New". It takes a few minutes, so don't think the program has frozen up on you. Once it's finished, you'll find that "Null" is no longer greyed out in the Upload window, and you can untick it. If you want to run a quick profile for verification after the LUT is uploaded , you'll have to enable a pattern size during the upload just as you did for the Null LUT upload in the beginning.

Author isticism
#3 | Posted: 19 Nov 2018 21:44 
Thanks, I never would have found that! I was able to successfully generate and upload the LUT to the monitor.

Unfortunately the resulting LUT was totally incorrect, throwing my whole monitor into some crazy green tint... but that's obviously resulting from a mistake elsewhere in the process that I need to root out.

Author RollsRoyce
#4 | Posted: 19 Nov 2018 22:42 | Edited by: RollsRoyce 
An overall green tint sounds like there could be a mismatch in that the monitor was expecting RGB but got YcBcR (component), or vice-versa. I'm not sure how that would happen in this case, but it's worth looking into.

EDIT: Suggest you read (or reread) the Eizo integration guide here:

Your answer might lie in monitor setup listed in the first few steps.

Author isticism
#5 | Posted: 19 Nov 2018 23:46 
Yeah, I'm pretty sure my initial problem is arising the same place you suggest: "Before commencing with the below calibration procedure, check the Eizo display is set correctly for the input signal to be used, with a valid video signal being applied to the video input to be calibrated - paying specific attention to the required image range, Data or TV Legal, by making sure the correct Input Range setting is in use from the display's OSD menu. Use the Light Illusion CalImages for this, following the Display Calibration - Initial Set-up guide. Also make sure the correct Colour Space has been selected." The problem is that all the documentation around TV/Data levels gets pretty generic on Lightspace documentation.

My monitor is a Eizo CG247X, connected to an iMac through a Blackmagic Ultrastudio Mini Monitor. There are a number of contingent settings that are not clearly defined in the relevant Lightspace documentation:

1. Eizo monitor setup menu "Signal Type": PC or Video
2. Eizo monitor menu setting for color mode "Input Range": Limited vs. Full vs. 109% White vs. Auto
3. Eizo monitor menu setting for color mode "Color Space": Auto vs. RGB vs. YUV 4:4:4 vs. YUV 4:2:2
3. Resolve project settings - Video Data Levels: Video vs. Full

The settings I had were:
1. Video
2. Full
3. YUV 4:2:2
4. Full

Which resulted in the green tint - at my wit's end about how to reconfigure these settings...

Author RollsRoyce
#6 | Posted: 20 Nov 2018 00:15 
It also mentions in the Lightspace Calibration section:
"Note: Some Eizo displays will NOT work correctly with YUV/YCrCb signal paths when using 3D LUTs, and MUST be set to RGB.
If when attempting calibration the image shows 'strange' colour shift with a 3D LUT active in YUV mode, the display is one with this issue. Additionally some Eizo displays have the patch generator 'after' the 3D LUT, so cannot be used to verify the uploaded calibration."

Author isticism
#7 | Posted: 20 Nov 2018 00:27 
So would RGB correspond to Full/Data levels?

Author isticism
#8 | Posted: 20 Nov 2018 00:38 
And/or would RGB correspond to the "PC" setting under the monitor's "signal type" setting (as opposed to the "video" setting)?

Author RollsRoyce
#9 | Posted: 20 Nov 2018 01:14 
RGB can be either Full (0-255) or Limited (16-235). YCbCr/YUV is 16-235. For your second question, the answer is "probably".

Author isticism
#10 | Posted: 20 Nov 2018 02:13 
OK, thanks for clearing some of this up for me!

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