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Display Calibration Light Illusion Forums / Display Calibration /

using offsets from a cheaper spectro with a recently calibrated good colorimeter?

Author blasetheodore
Mono
#1 | Posted: 8 May 2017 18:15 
I just got my K10a back from Klien's calibration, done by a Minolta CS-2000 spectro.

I used to use my i1pro 2 spectro to generate the offsets. But now I'm wondering what I'm gaining (or even losing) by doing that?

To be clear, the offset just accounts for the drift of the colorimeter over time, right? Or is it specific to how the meter interacts with the display type?

Am I better off using/not using the i1 for offsets with the K10a? I'm concerned the inaccuracy of the cheaper spectro would outweigh the aging drift of the K10?

Author blasetheodore
Mono
#2 | Posted: 8 May 2017 18:16 
(And forgot to check "watch this".)

Author Steve
Scene
#3 | Posted: 8 May 2017 18:57 
Generating an offset is attempting to match the Tristimulus to the specific spectral output of the display, using the Spectro as the reference.

If there are presets within the Tristimulus for your specific display they will be potentially be better due to the original matrix calibration, but only potentially...

Just because a high-end Spectro was used to re-certify and re-calibrate the K10-A doesn't mean the presets are accurate, as that will have been generated at a different time.

And since they were generated has the display manufacturer changed the backlight they use?

However, using a cheap Spectro with a high-end Tristimulus is rather self defeating.

The i1Pro2 is just not suited to the narrow spectral bandwidths of wide gamut displays.

You really need a narrow band Spectro to make the most of the K10-A.

And yes, I will try to make the default to follow any thread posted to... I just need to remember to do it!!!

Steve

Author blasetheodore
Mono
#4 | Posted: 8 May 2017 19:11 
Ok thanks Steve.

Understanding the spectral differences between display technologies is unfortunately over my head.
(Probe was calibrated by LCD, though I'm using an OLED.)
But I understand the i1pro2 doesn't have the spectral narrowness, which was my concern as well.

So the simpler question is.. Would you personally use the K10 to calibrate an OLED with or without the offsets created by a cheap i1pro2?
Or dartboard it with one of the OLED presets?
Or use "blank"?

Thanks,
Blase

Author Steve
Scene
#5 | Posted: 8 May 2017 22:01 
OLEDs are self illuminating, narrow spectrum displays - with very specific Metameric issues.
The only real approach is to use the Perceptual approach: http://www.lightillusion.com/perceptual_colour_match.html
(Or use a very, very narrow bandwidth Spectro, such as a CR-300...)

Steve

Author blasetheodore
Mono
#6 | Posted: 9 May 2017 14:28 
Thanks Steve.

I'd seen that article before, and understood the process, but didn't quite understand the logic. If you're able to manually dial in a white point that perceptually matches, why bother to change it back? Why not just leave it as is, and build your LUTs from there?

Author blasetheodore
Mono
#7 | Posted: 9 May 2017 14:30 
(which would mean that you would substitute your matrix white point when you build the final LUT)

Author Steve
Scene
#8 | Posted: 9 May 2017 14:34 
You need to use the new white point values as the target for the 'new' colour space.
You are not 'changing it back'.

Steve

Author Anger
Mono
#9 | Posted: 12 Oct 2018 10:44 
Steve:
The only real approach is to use the Perceptual approach: http://www.lightillusion.com/perceptual_colour_match.html
(Or use a very, very narrow bandwidth Spectro, such as a CR-300...)

Sorry Steve, I would really appreciate if you could make this concept more explicit. What I got it is that with a OLED (RGB/WRGB) display you can perceptually match a CRT/Plasma display white point OR buy a CR-300. Is that right? If I use a CR-300 I do not need to do perceptual matching.

Author Steve
Scene
#10 | Posted: 16 Oct 2018 21:16 
Narrow bandwidth Spectros 'should' work without perceptual matching, but how narrow would one need to be?
That would really depend on the spectral response of the display.
The CR-300 works well on the narrow bandwidth displays we have tested.
Will it work on all?
More testing would need to be performed...

Steve

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