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Advanced LightSpace Operation

 
 
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Author RollsRoyce
User - Mono 
#16 | Posted: 25 Sep 2019 14:08 
I'm very happy about it as well. The display I tested it on is an older CRT RPTV paired with a Radiance. The TV itself has a native gamut that on the CIE diagram is wider Blue>Green and Blue>Red but narrower Green>Red than Rec. 709, so it's enough of a challenge that I would just normally calibrate it to itself using a 3D LUT to linearize it and call it a day. It wasn't until I did the full LUT concatenation that I saw the Red - Yellow - Green line really pulled back to the Rec 709 boundary. Green was unsaturated a bit, but there's nothing for that. Having said that, the separate 1D and 3D LUTs, while not controlling that area nearly as well, still pulled Red in until it hit its target circle and managed to get Green within the 709 gamut triangle (still unsaturated). Not bad considering this was done with a 1D LUT generated from a "Grey Only Large" profile and a 3D LUT generated from a short 11^3 profile. You can see differences when comparing post-calibration verification charts, of course, but they really aren't visible in regular content. I may check later using Ted's disk. All in all, I'd say it's a worthwhile addition to the LightSpace toolkit.

Author mikela
User - Mono 
#17 | Posted: 16 Mar 2020 05:18 
Is my assumption correct that if creating a 1D LUT I do not need to use the "Augment Data" process if I am uploading to a Radiance using "Upload 1D Only". Then I would use that as the active LUT to create a 3D LUT which is then uploaded as "3D Only"? I assume the "Augment Data" process is used when you don't have the ability to upload the 1D and 3D LUTs separately?

Author Steve

Mod - Scene 
#18 | Posted: 11 Apr 2020 07:59 | Edited by: Steve 
Sorry Mikela, I missed that your post was waiting for 'moderation'.
You can post without restriction now.

As for 1D LUTs, you are correct that you would not use 'Augment' with them, as you can just use a large size 'Grey Only' profile as needed.
As to whether you can use the 1D first, and then perform a re-profile, and upload a 3D LUT, that will depend on the location of the 1D LUT in the image path.
It must be after the location of the 3D LUT to enable separate LUT adjustment.

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Htnut
User - Mono 
#19 | Posted: 15 May 2020 08:49 
Steve:
As to whether you can use the 1D first, and then perform a re-profile, and upload a 3D LUT, that will depend on the location of the 1D LUT in the image path.
It must be after the location of the 3D LUT to enable separate LUT adjustment.

Steve
Does the Lumagen have the 1D LUT after the 3D?
If not, what is the reason for supporting this feature with the Lumagen?

Author Steve

Mod - Scene 
#20 | Posted: 15 May 2020 09:04 
That's a question for Lumagen...
(Been a while since I last looked, so don't want to just try to remember - and I think Lumagen changed the location...)

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Htnut
User - Mono 
#21 | Posted: 16 May 2020 05:22 
Steve
I found this post from Jim Peterson:

The Radiance and Radiance Pro products have the 3D LUT before the 1D LUT. This is because when we were designing the 3D LUT we were working with Spectracal (Calman) and they requested that we move the 1D from before to after the 3D LUT. I initially had the 1D before the 3D because to me that seemed the best place to put it, but Calman wanted it after. Later, Steve of Light Illusions (Lightspace) said they prefer it before or having a 1D LUT in front of the 3D LUT and a 1D LUT after the 3D LUT.

Perhaps you should let Jim know that you are now happy with the way it is currently

Author Steve

Mod - Scene 
#22 | Posted: 16 May 2020 09:30 | Edited by: Steve 
No, it all depends on what you are using the 1D LUT for.

If you have it before the 3D you can use it as a 'shaper' LUT.
That is actually far more useful, as you can greatly increase the effective accuracy of the 3D LUT.
In such a workflow the 1D and 3D LUTs are treated as a single 'object'.

Having the 1D after the 3D means the two are separate objects. The 1D can be used to 'pre-calibrate' the display grey scale/gamma.
The 3D is then used for full calibration.

In a professional system (including displays) there should be 3 LUTs - 2x 1D, and a 3D, with the 3D LUT sandwiched between the 1D LUTs.

If you only have 1x 1D LUTs, it is far more useful to have it before the 3D LUT.

See the signal path here: https://www.lightspace.lightillusion.com/error.html#calibration_adjustments

Steve
Steve Shaw
Mob Boss at Light Illusion

Author RollsRoyce
User - Mono 
#23 | Posted: 25 May 2020 16:53 | Edited by: RollsRoyce 
Hi, Steve. This question is along the same lines as your last post, but has to do with ColourSpace, although I'm guessing the answer would apply to LightSpace as well. Last night, I used the latest CS beta to create and upload separate 1D and 3D LUTs to my Radiance 2020. As you had advised, I created and uploaded the 1D LUT first, basing it on a Large Gray Scale profile, then did a 12^3 profile to build the 3D CMS LUT. This resulted in the best fit to Rec709 that I've seen yet on my display. I used "Fit Space" when creating the 3D LUT, but don't remember what mapping I used to create the 1D. Should the two LUTs be created using the same gamut mapping method, or does it even matter?

Author Steve

Mod - Scene 
#24 | Posted: 25 May 2020 16:56 
Makes no difference - the choice is all yours.
There may indeed be situations where one method is better for 1D LUT generation (gray scale) and a different method is better for 3D LUTs.

Steve
Steve Shaw
Mob Boss at Light Illusion

Author RollsRoyce
User - Mono 
#25 | Posted: 25 May 2020 17:50 
Great! Thanks, Steve.

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