Author Topic: QD-OLED 3 Month review  (Read 819 times)

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Offline tp4tissue

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QD-OLED 3 Month review
« on: Fri, 17 May 2024, 09:11:38 »
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Wide viewing angles.
QD-Oled has no polarizer and is emissive, this means it has no off axis, gamma shift, tinting (chroma drift).
 - This is useful in that one can sit very close to the TV for immersiveness, and the edges are the same color/ brightness
 - On LCD the edges drift as the backlight leaks diagonally across the pixel pane, this causes the color to washout, become hazy, IPS included.
 - The larger the color drift, the more the eye perceives a shimmer, as the left and right eye receive different color information.
 - On LG's WOLED, there's a tint off axis due to its polarizer, but it gains better black performance in lit rooms as a trade off. The tint is slight enough such that you wouldn't notice unless pointed out.
 - Tint is much worse on LCDs.

Fast pixel transition.

A 144hz oled has the same motion clarity as a 220hz non-strobed lcd. There is still persistence blur due frame hold times, so peak to peak tech comparison, it's not as clear as STROBED-Lcds or CRTs, both of which can reach <1 ms persistence. 360hz/500hz oled are very close to perfect, Strobed LCD will still beat it, but it's becoming impractical to generate that many FPS from the content side.
- This is important because Strobed LCD can give you <1ms persistence @ 60-120hz @ usable brightness. OLED can not achieve that.
- If you have a 500hz oled, and you're not pumping out 500fps, that means you will introduce pixel persistence blur, the same as if you were running 250hz.

Oled Black level.
 - It's not infinity : 1 contrast.
 - The pixels need dithering to initiate low value inputs, so if you wanted to light up a single RGB 1:1:1 pixel, the screen has to initiate a 50pixel wide dithering patch. Very close to black, each pixel has a forward voltage, this will overshoot or undershoot the target, so you need dithering. In real movies/ images there is noise, other than black bars, there are very few completely "black" spaces that are noise free. This means that within black patch there is almost 0 probability of 0,0,0 pixels being rendered. The effective contrast ratio is therefore not infinity:1. 
 - In real content, Oled's contrast ratio is ~10,000:1 in SDR @100nits, 100,000:1 in HDR 1000nits.
 - Yea, that's more than you realistically need, since the human eye has a ~1000:1 static contrast.
 - So the contrast is very good, but not as advertised. Same goes for LG's WOLED.

Sensitivity to Heat.
- Back in the days of CCFlourescent backlighting  LCDs, before LED backlighting, temperature would cause a color / hue drift. LEDs made it alot more stable, not 100%, but much better.

- Sad to report, well the problem's back with oleds.  The response of the pixels change pretty radically with 5-10 degrees difference in ambient temperature. You can measure the display in +/- 0.15 gamma up and down across big temp swings. So, if you wanted gamma 2.2, colder you get 2.35, warmer you get 2.05
- Not enough to affect general use, but yea, now you know.
- It's fine if you are always air conditioned.

Gamut.
- QD's claim to fame is purer RGB primaries, which result in the largest gamut short of laser.
- This is delivered as promised, Although weaknesses in Software leads to less than perfect implementation.

Samsung's S90C software.

- Software is challenging for enthusiasts because it has un-defeatable tone-mapping/ contrast / ABL even in film-maker mode.
- LOTS of bugs.
- Auto gamut detection is broken, thankfully, this function isn't really necessary 99% of the time, but it's something to be aware of.
- Game mode gamut problems (magenta)
- General Menu system is efficiently laid out. Quick access to most used settings are well plotted.

10-Bit Support.
- Yes, it properly supports 10bit/12bit input, gradients are very smooth, not as smooth as pro-panels, but smooth.
- Tested with software dithering disabled, the panel still renders decent gradients, that means its native dithering is functioning properly.
- Alot of TVs will take a 10bit signal, but its dithering engine is so bad, that it's only effectively an 8bit display.
- Near black, because of the dithering, you can't say it's got 1024 shades of grey,  it's got 1024 shades of greyish.
- Near black is a fuzzy affair.

Power Use.
OMG do large Oleds use alot of power. It's insane. Switch to darkmode on all UI-s unless you just want to burn money.
A 122nit white screen is 170 watts. The electronics inside is ~60 watts, the 110watts is just the panel.
At max, the Oled pulls 340 ish watt total sustained for a 200nit whitescreen, of course it can hit that in HDR as well with half the screen.
The Room gets very hot.
Gaming PC, 7900xtx, You've effectively got a 600-750 watt heater, in the middle of summer.

LCDs are much more power efficient at equal-and-higher brightnesses.

Overall.
The technology is nearing maturity. Panel uniformity could be better, but it's not awful like in the beginning.
Sony has better panel driving than Samsung, but the Sony tax is just too high.

Tp4 can fully recommend QD-oled to the general public. 

Computer side of things, Samsung TVs are not ready for color critical viewing, but some Monitor iterations out there might be.

Offline tp4tissue

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Re: QD-OLED 3 Month review
« Reply #1 on: Mon, 10 June 2024, 21:40:21 »
Could've sworn people said QD_Oled doesn't have chromanance overshoot. Much less perhaps. But it totally does have near black overshoot.