gordonF:
Did you save the LUT once it was created? How do you know there is no LUT actually in the CMS slot in the Lumagen? The obvious way to check if anything has been altered is to turn on service mode in scaler MENU 0 9 1 0 OK then go to MENU>OUT>CMS> CMS in use and go in to the 21 step greyscale and see if anything has been altered. If there is a LUT it will definitely have written new values in there.
Thank you for pointing out this sanity check. This would have been a nice fix/mistake but yes, there are new values (nice 21 point values) written in the CMS into which I uploaded the LUT.
Steve:
You do not need to run a ramp and a cube profile, as the ramp is within the cube - but you can use different profiles that deliberately have larger ramp patches.
I double checked and apparently did not save the CUBE profile but only the RAMPS (specially the Grey Ramps Primary and Secondary 8 bits), so that is what I created the LUT with, and uploaded. This has a minimal amount of data for a 3D LUT and 1D LUT so in theory while not particularly nuanced and detailed, this should get me something reasonably accurate?
To create the LUT I selection Source UHD 2020, Destination, the Profile I measured, and made no other selections on the LUT Generation page. The resulting LUT said it was 42% within target, which makes sense. The display has a greater than 709 coverage but not even full P3 coverage. But this shouldn't matter? I simply want to have the content track correctly as far as the display is capable to displaying.
And for the TPG Range in the upload screen I selected SDR. Perhaps I should have selected HDR. The Lumagen manual page (https://lightillusion.com/
lumagen_manual.html) doesn't discuss this but the one screen shot shows HDR selected. And perhaps when uploading a lut that maps 709 content to my measured profile I should select SDR for the TPG type in the LUT upload screen. Just in case, I did uploaded it again, using HDR in the TPG Range.
Then I measured again and those measurement are attached to this post. I ran these measurement to see if they are consistent with why I would expect with the LUTs in place, but they look poor.
Maybe low IRE readings are a challenge off the screen so perhaps I should do the 1d LUT profiling with the meter pointed at the projector (to make sure there is enough light to get a consistent result) and do the 3d LUT with the meter pointed at the screen (to take into account any color shift the screen introduces)?
EDIT: Some more investigation, and I believe these are the pieces I need to revisit.
1. I left Extra Delay at the default setting. I will try this procedure to set it, next time: "The Auto button can be used to set the Extra Delay automatically, by first opening a patch window on the display to be profiled, placing the probe on it, and pressing the Auto button."
2. The LUT I created was just using the "Grey Primary & Secondary Ramp +" measurements (and without the Extra Delay "auto" option set up). I was thinking this was enough to learn the workflow and get a basic LUT in place. I may have been wrong?
3. I did NOT do this in the Lumagen before the measurements that were used for the LUT: "Set the 2020 <-->601/709 = Auto Convert, except while calibrating. If the LUT is used to convert between 2020 and 601/709 then set the "2020<->601/709" option to "off". " Nor did I undo that after measuring for the LUT and uploading it, because I did not: "Once calibration has been completed enable the CMS1 → Colorspace → Colorspace = Auto Convert." So that might have impacted my results. But I am not sure whether my graphs indicate that.
4. And I did not do this:
"To check for the correct set-up the following tests can be used.
Using a controlled video source display a zero black image
Change the In/Out HDMI options in turn and check for accurate black levels
(A probe can be used to check black levels)
Generate a New Unity Bypass LUT, and use the LUT Tools to set Gamma to 2.0
(If the ColourSpace license you have doesn't have the LUT Tools option, use the LUT Image to make a similar gamma change via an external graphics program)
Using a controlled video source display the Light Illusion BrightnessCal image
Again, change the In/Out HDMI options in turn and test by uploading the Gamma Change LUT created above
When the correct Radiance configuration is set the Gamma LUT will operate correctly, altering the image Gamma, with NO change to zero black."
......because I don't see any in/out hdmi options in the ColourSpace manual and searching for "In/Out Hdmi" in the Lumagen manual also returns no hits.