Even OLED is a flawed technology

[elvn]

On that actual prev topic, as I understand it LG OLED tvs use an all white array of OLEDs through a color filter layer which is LG's proprietary tech that got around the worst of the single colors fading first issue. It's sort of like a per pixel FALD, in the way that dual layer LCD is trying to do (but at 1080p on a 4k so far so not exactly 1:1 on those). Also obviously much slimmer and cooler running on OLED, plus viewing angles, response time etc but the comparison stands.

LGD's WRGB architecture - which creates 4 sub pixels using color filters (reg, green, blue and non-filtered) to create a colored image from a single white OLED pixel - is less efficient and less color-pure compared to a real RGB sub-pixel architecture, but WOLED displays are much easier to produce as there's less need for subpixel patterning.

They also add a white pixel/clear filter in order to cheat the color brightness levels a little higher to your eyes without driving the OLED emitters brighter. So their color is not as accurate and loses some color saturation on the brightest tones as it's technically slightly white washed at higher levels. That as well as ABL on the HDR models it makes them impossible to calibrate properly. Still the C9's can display almost the entire DCI P3 color space (97.21%, 98.68%) and get 69% rec 2020 coverage.

https://www.rtings.com/tv/reviews/lg/c9-oled

The C9 can display a wide color gamut, which is great for watching HDR content. It can display almost the entire DCI P3 color space, which is great, and has good coverage of the wider Rec. 2020 color space.

I guess wear in makes sense in regard to persistent images. It sounds a lot more pleasant than "spot rotting" where you'd rather have the organics die slower and evenly like the rest of the screen over many years. A plant who loves shade having some of its leaves in direct sunlight too long go brown comes to mind. With HDR I'd compare display's constitution as if on different stove top burner settings.. simmer, medium, high. OLED has to keep on the low end or it will burn out it's glassware in spots .

 

[elvn]

Update to the White oled issue in 2019 C9 oleds from https://www.flatpanelshd.com/review.php?subaction=showfull&id=1559035462

We are told that other small tweaks in the second-generation Alpha 9 include a modified saturation curve leading to less desaturation in colors at high luminance, and our measurements and viewing tests seem to support this but we cannot be sure without a 2018 LG OLED in side-by-side testing. In addition, LG has implemented a 'Peak brightness' setting that can turn off white boost (that starts from around 400 nits), if you like. The same setting option can be used to limit peak brightness if you feel that it is too high in a very dark viewing environment. Lastly, LG has fixed a bug in its look-up table that let to greenish tint on some skins colors.

The above sounds great to me as options anyway. Any increase in saturation vs white wash effect of WOLED would be appreciated. You could in fact turn off white boost but your hdr color range above 400nit while more saturated would be a lower color brightness HDR ceiling.

They also added some tone mapping tech to try to keep detail that gets washed out /clipped at higher brightness limitations of OLED but it sounds kind of hacked to me. At least it's fully user adjustable incl. off.

To address the limited peak brightness levels in OLED, LG has employed dynamic tone-mapping, this year with a new, improved algorithm (LG calls it 'Dynamic Tone-mapping 2'). The purpose of dynamic tone-mapping is to try and maintain details in the brightest tones that go beyond the panel's brightness capabilities. This is done by adjusting the brightness curve (PQ EOTF) and how it rolls off at the top (brightest tones). This roll-off can actually also be adjusted manually this year as part of LG's new auto-cal features. Still, what dynamic tone-mapping is, is essentially a patch solution until the capabilities of the display technology improve. Hollywood argues in favor of a "hard clip", meaning that brightness is clipped at the TV's maximum brightness capabilities (around 700 nits for C9) and highlight details above disappear. On the other hand, parts of the gaming industry seem completely clueless as to what HDR is and often just max out their games at 10000 nits peaks even though they have not even checked how the game presents itself at those values (there are no reference monitors with 10000 nits peak brightness). As a side note; that is one of the reasons why Sony PlayStation and Microsoft Xbox are getting together to fix HDR in gaming.

We examined LG's new dynamic tone-mapping solution and it can effectively alter the brightness curve to resolve more highlight detail. With our 4000 nits test pattern, it resolved highlight details up to 4000 nits but of course these levels will not be accurate (you just see the altered details). You are free to select what compromise you prefer through LG's picture menus - or for more advanced users with the new auto-calibration features. We applaud that LG is giving users choice in this area. The system also ties in with LG's 'AI Brightness' feature that aims to adjust brightness in the TV according to your viewing environment (dark, bright, night day etc). Here, LG has actually implemented two solutions. One is from Dolby and works with Dolby Vision content, while the other is LG's that works with HDR10 and HLG content. We know that many have complained about HDR movies being too dark when watched in a bright living room and LG TVs can now more effectively adjust brightness by measuring your environment and feeding this back into the TV's dynamic tone-mapping system that will try to increase overall brightness by changing the brightness curve. Again, this feature is optional.