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Display Stabilisation, & Volumetric Accuracy

 
 
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Author Steve

INF
Male
#16 | Posted: 17 May 2018 21:46 | Edited by: Steve 
When calibrating any HDR display you MUST set it to a standard Power Law gamma, and then profile it.
You can then calibrate to any EOTF you want.
You cannot profile an HDR display with an EOTF active (especially one with roll-off/tine mapping) and then use that profile to calibrate it.

So, all the above graphs for both displays are with a standard Power law gamma, with Peak Luma set to HDR levels (700 to 800 nits in this case).

As there is no PQ EOTF active the displays should profile to themselves near perfectly, just as for the SDR tests that started this thread.

That is why the WOLED display data is so appalling - there is no PQ EOTF active, so the results should be near perfect.

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Ampallang
ZRO
#17 | Posted: 19 May 2018 06:59 | Edited by: Ampallang 
Hi Steve,
Thanks for that great thread. So also thanks James for giving some ideas for improvement in patch Sequenz.

Funny User d-nice

www.avsforum.com/forum/139-display-calibration/2962814-2018-lg-oled-calibration-user- settings-no-price-talk-4.html#/topics/2962814?page=11

was mentioned my thinking already with screen uniformity. So brightness is no big matter but color accuracy due to the white sub Pixel and heat. There must be a screen uniformity test before calibration and then the patch Sequenz must switch only between the fields which passed the uniformity test.
So a patch squenz in my idea have the uniformity test first all passed fields will be kept in the field lottery. Then you measure several patches with screen stability and well optimized patch Sequenz and switch/rotate between passed field spots to finish measurement. Didn't know if this could be programmed. But this will overcome the cool down time with in use of contact meters. Instead of just calibrate only 5 to 10 minutes and then to wait.

Author RollsRoyce
ZRO
#18 | Posted: 21 May 2018 16:45 
Sorry, but it's probably not a good idea to use meters in contact mode with any display that has heat issues. The cool-down time is likely used to stabilize the display's temperature -which affects the display's luminance - rather than for contact reading.

Author Steve

INF
Male
#19 | Posted: 21 May 2018 16:51 
Where does it say a meter was used in 'contact' mode?
We have used a CR-100, as well as the cheap i1D3, to verify the results.

The result is that the thermal instability seen in the WOLEDs is the display, not the probe.

Steve
Steve Shaw
Mob Boss at Light Illusion

Author RollsRoyce
ZRO
#20 | Posted: 21 May 2018 16:57 | Edited by: RollsRoyce 
Right at the end of his post, Steve: "But this will overcome the cool down time with in use of CONTACT meters. Instead of just calibrate only 5 to 10 minutes and then to wait." (emphasis mine). I probably should have quoted his post. My bad.

Author Steve

INF
Male
#21 | Posted: 21 May 2018 17:01 
Ah - I missed that (to be fair I actually struggled to read and understand Ampallang's post...).
But I agree - we would not recommend using a probe in direct contact mode with displays that have screen heat generation.
You do not need a large air-gap, and should have a 'hood' to prevent light leakage.

So sorry I missed that in Ampallang's post!

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Ampallang
ZRO
#22 | Posted: 21 May 2018 17:48 | Edited by: Ampallang 
Hi Steve,
I didn't say that you use any contact meters I was only suggesting about the screen uniformity and devide the screen into good and bad sections to overcame the heat. This would be much easier with probes like the id3 which is a contact meter where u save the time for prober alignment. Hope this is a little more understandable for what Iike to say beforehand.

Author Steve

INF
Male
#23 | Posted: 21 May 2018 18:11 
Sorry to say I'm not really following your thoughts.
What are proposing exactly?

Steve
Steve Shaw
Mob Boss at Light Illusion

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 Display Stabilisation, & Volumetric Accuracy

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