Oled tv rolling scan

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Alamar
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Oled tv rolling scan

Post by Alamar » 14 Feb 2017, 09:48

Hello
Just wonder, are there any backstage news about implamenting rolling scan technology already used in Oculus Rift/Sony Trimaster PVM-2541 etc. in oled tv or monitors? I mean if there any plans or probability? I feel it would be best feature lg oled could add and upgrade their tvs, would really love to see real crt like motion in newer displays again. Also hz number should be at least 100hz if not more (especially that tv are much bigger than crt were) for a good effect I guess.

ps - and how would it work with hdr and other new technlogies, no problem?

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Re: Oled tv rolling scan

Post by Chief Blur Buster » 14 Feb 2017, 10:45

Alamar wrote:Hello
Just wonder, are there any backstage news about implamenting rolling scan technology already used in Oculus Rift/Sony Trimaster PVM-2541 etc. in oled tv or monitors? I mean if there any plans or probability? I feel it would be best feature lg oled could add and upgrade their tvs, would really love to see real crt like motion in newer displays again. Also hz number should be at least 100hz if not more (especially that tv are much bigger than crt were) for a good effect I guess.

ps - and how would it work with hdr and other new technlogies, no problem?
Rolling scan is not particularly difficult at all; it solves the OLED motion blur nicely (Article on Blur Busters).

It is the amount of light output an OLED can provide -- which makes it extremely difficult to produce a very bright rolling scan OLED. They would be dimmer (at equivalent persistence) than a strobed LCD which is still sometimes dim.

OLED rolling scan can work with HDR but the chief problem is OLED light output. Rolling scan will reduce peak lumen output -- many HDR specifications have minimum light output specs -- IIRC, one of the specs (Dolby Vision, I think), specifies something like 500 nits for OLEDs and 1000 nits for LCDs.

The more refresh rate, the easier it will be to keep brightness during rolling scan, due to more rolling scan passes (of the same persistence -- "ON" duty cycle).
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Manimal 5000
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Re: Oled tv rolling scan

Post by Manimal 5000 » 14 Feb 2017, 13:05

My rift is great, but I have given up on OLED showing up in PC monitors in the next few years. Dell dropped it's plans for one. Samsung gave up on it altogether. The lighting industry (Philips, Osram) have pretty much dropped it for now. They sight cost, life-time issues and better prospects in LED. LG seem to be going strong with OLED tvs, but their panels aren't suitable for monitors. The newest reach 1000 nits with very aggressive ABL . LCDs do twice that without ABL, allowing them to strobe with CRT-like motion while taking the brightness hit. I don't see a good motion OLED monitor until they fix the life-time issue if ever. Something better may come along first. Samsung predicts their emissive Q-LED monitor around 2020 (basically the same thing as OLED without lifetime issues). In the mean time ULMB does the trick for me, if you can put up with LCD viewing angles and cloudy blacks.

Alamar
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Re: Oled tv rolling scan

Post by Alamar » 17 Feb 2017, 09:08

Manimal 5000 wrote:My rift is great, but I have given up on OLED showing up in PC monitors in the next few years. Dell dropped it's plans for one. Samsung gave up on it altogether. The lighting industry (Philips, Osram) have pretty much dropped it for now. They sight cost, life-time issues and better prospects in LED. LG seem to be going strong with OLED tvs, but their panels aren't suitable for monitors. The newest reach 1000 nits with very aggressive ABL . LCDs do twice that without ABL, allowing them to strobe with CRT-like motion while taking the brightness hit. I don't see a good motion OLED monitor until they fix the life-time issue if ever. Something better may come along first. Samsung predicts their emissive Q-LED monitor around 2020 (basically the same thing as OLED without lifetime issues). In the mean time ULMB does the trick for me, if you can put up with LCD viewing angles and cloudy blacks.
Is this life-time issue still true with lg oled tv? I heard voices that both life-time and burn in is similiar now to previous technologies crt and plasma.
We talk about 1000 nits, 2x1000 nits* (cd/m2) but I use my lcd with 80-180 cd/m2 and also used for very long time crt with was even much darker and it was fine. Last Panasonic plasma models also aren't super bright and they are great.

ps - Of course using strobing will hit brightness but how much?

Manimal 5000
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Re: Oled tv rolling scan

Post by Manimal 5000 » 17 Feb 2017, 09:53

Alamar wrote:
Manimal 5000 wrote: Of course using strobing will hit brightness but how much?
These are good questions Chief might know.

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Re: Oled tv rolling scan

Post by Chief Blur Buster » 17 Feb 2017, 11:57

Brightness impact is /usually/ proportional to desired reduction in motion blur.

50% less motion blur = 50% less brightness
90% less motion blur = 90% less brightness

As a rule of thumb (we call this "The Blur Busters Law") -- every 1ms of extra strobe length translates to 1 pixel of extra motion blurring during 1,000 pixels/second motion. Thusly, you halve strobe flash length (duration of visible frame), you halve motion blur. If brightness is constant during the ON cycle, then you also halve brightness too.

A good demo is TestUFO operating at 960 pixels/second (a number almost 1000 that's still evenly divisible by 60, 120 and 240Hz), and it has always reliably always followed this for strobed displays (strobe backlights & OLED rolling scan), at least those displays that have very clear strobe illumination curves (e.g. more squarewave than sawtooth like CRT phosphor decay).

Some backlights use extra voltage surges for brighter shorter pulses. Not all monitors do this, but some LightBoost monitors do (cite: StrobeMaster's Display Corner). LED's are tolerant of being overdriven for short time periods, so this behaviour is taken advantage of, to attempt to compensate for the brightness reduction. This helps reduce brightness loss somewhat, when reducing motion blur.

The blur-vs-brightness tradeoff is why several of us like adjustable strobe backlights, like "LightBoost 10% vs 50% vs 100%" for LightBoost monitors, as well as "ULMB Strobe Duty" in ULMB monitors.
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RLBURNSIDE
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Re: Oled tv rolling scan

Post by RLBURNSIDE » 09 Mar 2017, 00:02

Just a word of caution, 60hz OLEDs with rolling scan will visibly flicker. I work in VR and I can see it (in brighter scenes) on 60hz low-persistence scanned HMDs (such as those fancy 5K models that mere mortals can't buy yet haha). It's like CRT that way. Brighter scene = more perceived flicker. It's still stunning though.

But I'd get min 90hz or ideally 120hz VR headsets and TVs if you want rolling scan, otherwise it could be headache inducing over the long haul.

A recent Nature article (making the rounds on twitter lately) shows that we perceive flicker even up to 500hz:

http://www.nature.com/articles/srep07861

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Re: Oled tv rolling scan

Post by Sparky » 09 Mar 2017, 08:33

RLBURNSIDE wrote:Just a word of caution, 60hz OLEDs with rolling scan will visibly flicker. I work in VR and I can see it (in brighter scenes) on 60hz low-persistence scanned HMDs (such as those fancy 5K models that mere mortals can't buy yet haha). It's like CRT that way. Brighter scene = more perceived flicker. It's still stunning though.

But I'd get min 90hz or ideally 120hz VR headsets and TVs if you want rolling scan, otherwise it could be headache inducing over the long haul.

A recent Nature article (making the rounds on twitter lately) shows that we perceive flicker even up to 500hz:

http://www.nature.com/articles/srep07861
I would say flicker artifacts are distinct from perceiving flicker, and there really is no single threshold at which we can no longer perceive those artifacts, what matters is how far the image moves across the retina between pulses, and on the contrast. If something is moving really fast, you need a really high frequency. Say you're looking at the center of the screen and you move your cursor across the screen at 20,000 pixels/second, Even with 1khz polling and a 1khz display you're going to see a bunch of discrete images of the cursor about 20 pixels apart. Now, if you move the cursor 1/10 the speed, those discrete images are going to blur into each other. A display with "perfect" motion reproduction would have ultra low persistence and 100% duty cycle, so objects your eye is tracking would have no motion blur, but objects your eye is not tracking would be smoothly blurred. The only way to do this is extremely high refresh rates and frame rates.

One of the most annoying places I see these artifacts are when driving where a car next to you has LED brake lights with a crappy driver circuit.

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Re: Oled tv rolling scan

Post by Chief Blur Buster » 11 Mar 2017, 21:25

Direct detection of flicker does diminish fairly early (e.g. usually below 120Hz).

However human indirect detection of flicker can approach 10KHz (ish) via stroboscopic side effects.

Image
(from this thread)

So, humans, can indeed see side effects from PWM even well into thousands of Hz, through various stroboscopic stepping edges. Here's an example of what happens when you combine PWM + motion.

Image

Moderate-speed head-turning on 4K VR can yield 8000 pixels/second. Plenty of opportunity for stroboscopic stepping effects to still be visible. Due to the difficulty of lowering persistence while avoiding strobing (1ms persistence without strobing = 1000fps). We'll be stuck with stroboscopic stepping effects for a very long time to come (during stationary gaze with motion going past). Artificial GPU motion blur can be added to avoid stroboscopic stepping effects -- but that's additional motion blur above-and-beyond natural motion blur in the human brain. Lots of fascinating reading in this thread.
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Alamar
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Re: Oled tv rolling scan

Post by Alamar » 21 Mar 2017, 21:06

New LG OLED TV will be real 100/120hz:
https://www.avforums.com/review/lg-65w7 ... view.13308
but price :P

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