Why we need 1000fps@1000Hz this century -- Valve Software (Michael Abrash) comments - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 42 Old 08-01-2013, 01:49 PM - Thread Starter
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EDIT: This is an old 2013 post, but with many newer replies. Also, Michael Abrash is now Chief Scientist at Oculus VR -- low persistence OLED -- so these are very reputable writings.

EDIT 2018: A more modern article that educationally explains persistence is Blur Busters Law: The Amazing Journey To 1000Hz Displays

Michael Abrash of Valve Software has a great article about the problems of trying to simultaneously solve motion blur, judder and strobing when using virtual reality headsets. (In Comments section, Michael also complimented the work Blur Busters is doing). He has several great explanations about these problems, and also touches upon the benefits of 1000Hz-refresh displays.

"Down the VR rabbit hole: Fixing judder"
http://blogs.valvesoftware.com/abras...-fixing-judder

Essentially, the Cliff Notes version of his article:
- Low framerates -- problematic for both motion blur and/or judder
- High framerates -- better, but still have motion blur even at [email protected]
- Strobing -- solves motion blur but adds problems (flicker problem/stroboscopic problem)
- [email protected] -- Simultaneously fix motion blur, fix flicker, fix stroboscopic/stepping effects

Problem: Motion blur of eye-tracking motion blur on discrete-refresh displays:
.
Using Michael Abrash's diagrams, and corroborated by his vision researcher friends, I've arranged the diagrams in way that helps people understand why true [email protected] will eventually become necessary sometime later this century.
.
Simplified illustration for eye-tracking at 60fps @ 60Hz sample-and-hold (e.g. LCD)
.


Simplified illustration for eye-tracking at 120fps @ 120Hz sample-and-hold (e.g. LCD).
Less motion blur.
.


Simplified illustration for eye-tracking at 60fps @ 60Hz flicker driven (e.g. CRT).
Less motion blur too. But problem if you stare stationary (see next section).
.


Simplified illustration for eye-tracking in real life.
No motion blur bottleneck. No stroboscopic problem.


Problem: Persistence, the stroboscopic stepping effect while staring stationary while object moves past

This creates stroboscopic stepping effects (at low framerates, this is the common sensation of judder). The stepping effect can still be visible even at 120Hz and 240Hz. Visualize a fast moving object which creates a non-continuous trail, e.g. object moving 240 inches per second leaves a 1-inch dotted trail if you're just staring straight ahead. This is fixed by adding motion blur, but that is undesirable in many situations. For VR, you want perfect clarity without motion blur.
.
Continuous illumination (e.g. most LCD)
.


Half persistence (the frame is illuminated half the time)
.


Zero persistence (e.g. laser displays and short-persistence CRT's resembles this)


Problem: Persistence, the stroboscopic stepping effect while staring stationary while object moves past

.
Blur Busters UFO Motion Tests

I let Michael Abrash know about the UFO motion tests, of which Michael likes very much. This is very relevant into the "pick-your-poison" problems of finite-framerate displays. Before proceeding, make sure you understand how these animations work. View these links on a recent fast computer using Google Chrome or another browser supporting perfect framerate=Hz animation.

An excellent animation of eye-tracking-based motion blur:
www.testufo.com/#test=eyetracking (use a supported browser)

An excellent animation of how strobing reduces motion blur:
www.testufo.com/#test=blackframes (use a supported browser)
This also brings some strobing disadvantages

The problem when using virtual reality headsets, you've got head turning that creates very fast horizontal motion. This creates fast panning which can be quite motion blurred. Fast head-turning can create lots of motion blur.

First, look at the stationary image of the Eiffel tower.
http://www.testufo.com/#test=photo&p...ffel.jpg&pps=0
This is very clear on almost all displays.
- You can count the number of cars under the Eiffel Tower
- You can count the lattices in the Eiffel Tower

Let's simulate even just a slow head turning speed that's approximately 30 degrees per second (VR headsets):
www.testufo.com/#test=photo&pps=1920&photo=photo-eiffel.jpg (use a supported browser)
Maximize your web browser window on your display (computer or HDTV). Stare fairly close, at a view distance approximately equal to screen width. Now you're viewing motion that's moving approximately 30 degrees per second. That's only a slow head turning speed.
Look at how motion blurry it is on your LCD.
- LCD will show a lot of motion blur
- CRT will show stroboscopic stepping effects
- Even at 120Hz.
- Even at 240Hz.
- Yes, even at perfectly-done 480Hz.

Animation Self-Test Challenges

Challenge for motion blur.
www.testufo.com/#test=photo&pps=1920&photo=photo-eiffel.jpg (use a supported browser)
Track your eyes on the details of the moving photo above
- Try to count the number of cars under the Eiffel Tower
- Try to count the lattices in the Eiffel Tower
You can do typically easily do this on a CRT, but not on most LCD's (except LightBoost)
On a CRT with short-persistence phosphor, the fast moving image remains crystal-sharp.
Also crystal sharp on a LightBoost 120Hz monitor running ToastyX Strobelight programmed to 1.4ms strobes (Control+Alt+1).

Challenge for stroboscopic effect:
www.testufo.com/#test=photo&pps=1920&photo=photo-eiffel.jpg (use a supported browser)
Stare stationary ahead.
- Put your finger along the top edge of the moving photo, at the vertical level where the Eiffel Tower antenna passes underneath.
- Now stare at the finger.
- Notice the strobing effect of the Eiffel Tower antenna, as it passes underneath. You see multiple antennas near the finger.
- Even with 240fps frame interpolation, the strobing effect still remains if you're viewing at this fixed point during 30-degree-per-second motion (the speed of a slow head turn). So 240fps is not enough to fix the stroboscopic effect. There is no consumer display/monitor/HDTV that exists in the world, that fixes this stroboscopic effect problem. It's an artifact that exists on all finite-framerate displays, and diminishes as you go higher in framerate/Hz.

And this is Why [email protected] is Useful Progress

From the perspective of fast-action computer gamers, the persistence of having 1ms frame samples is benefical (the CRT effect) in completely eliminating perceptible motion blur, but even at high-refresh-rate CRT gaming when staring at the videogame crosshairs while doing strafes or turns in video games, you can see stroboscopic effects of finite-framerates (even on 21" high bandwidth professional CRT's being driven at 240Hz). Adding motion blur fixes this, but then you've got the motion blur problem. How do you fix motion blur AND the stroboscopic effect? Simple. [email protected] (or beyond).

So, this century, we will have a use for [email protected] -- in some applications such as FPS gaming, simulators, racing, military training, VR headsets, and everything else that requires all human eye effects to be done naturally (e.g. display doesn't enforce stroboscopic and motion blur limitations upon you). Otherwise, we will never reach Holodeck-league imagery.

Thanks,
Mark Rejhon
www.BlurBusters.com - Everything Better Than 60Hz(tm)

Last edited by Mark Rejhon; 01-28-2018 at 05:16 PM.
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post #2 of 42 Old 08-02-2013, 11:25 AM - Thread Starter
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Crossposting my public communication with by Michael Abrash of Valve software who complimented on my work; it appears that he seems to understand and agrees with the work that Blur Busters is doing.
Quote:
Originally Posted by Mark Rejhon 
I am the owner of Blur Busters, and the author of the Blur Busters Motion Tests.
I want to compliment you on your excellent write-up! I created some HTML5 animations that sync to VSYNC in some browsers, view these below links in Google Chrome:

An excellent animation of eye-tracking-based motion blur:
http://www.testufo.com/#test=eyetracking

An excellent animation of how strobing reduces motion blur:
http://www.testufo.com/#test=blackframes

Strobing is a great solution to eliminating motion blur. An example is viewing http://www.testufo.com/#test=photo when LigthBoost is enabled. (ToastyX Strobelight now makes it easy to turn ON/OFF LightBoost via a hotkey). One big problem of strobing is you have to refresh the LCD in the dark, before strobing the backlight on clearly refreshed frames. This adds an average half a frame of input lag, which can hurt VR. However, one could also use a high refresh rate (e.g. 120Hz or 240Hz) to fix this type of lag. 120Hz strobing is far more comfortable on the eyes than 60Hz strobing. Shorter strobe flashes reduce motion blur, so a 90%:10% dark:bright duty cycle reduces motion blur by 90%, but can darken the image by 90%.
Quote:
Originally Posted by Michael Abrash @ Valve Software 
July 30, 2013 at 3:34 pm
Hi Mark – great to hear from you! We really appreciate your work, and in fact Aaron already forwarded around your animations.

We have done black-frame insertion at 120Hz, and it works pretty well, but it’s still hard to get the LCD to settle quickly enough.

–Michael
Quote:
Originally Posted by Mark Rejhon 
July 30, 2013 at 4:25 pm
Thanks for the compliment. This probably means you’re familiar with my LightBoost research so far. Have you tried ToastyX’s new Strobelight Utility, which programs a LightBoost 2D motion blur eliminating strobe backlight without needing 3D Vision drivers, and without registry hacks? It also can reprogram the strobe length, via keyboard shortcuts as well:

Control+Alt+Plus = turn on LightBoost strobe flashing
Control+Alt+Minus = turn off LightBoost strobe flashing
Control+Alt+0 = Lightboost 100%, using 2.4ms flash
Control+Alt+5 = Lightboost 50%, using 1.9ms flash
Control+Alt+1 = Lightboost 10%, using 1.4ms flash

It creates a sort of an equivalent of a programmable-persistence display (to a certain extent). Both Adam Simmons (of TFTCentral.co.uk) and I (of Blur Busters) have used an oscilloscope and found that LightBoost strobe lengths are programmable in approximately 0.1ms increments. Our measurements varies a bit, but both of our oscilloscope measurements match within +/-0.1ms and we’ve established that motion blur of a LightBoost strobe backlight is linearly proportional to its strobe length. It does not eliminate stroboscopic/wagonwheel effects, so [email protected] is still a useful Holy Grail.

The strobe length differences actually show up visually in motion tests too. We were impressed that we could tell the 1 millisecond difference, in a fast-moving motion test:
http://www.testufo.com/#test=photo&pps=1440
(while running ToastyX Strobelight with LightBoost enabled)
Running this animation while hitting Control+Alt+0 versus Control+Alt+1. The windows in the castle at the top obviously became clearer during 1.4ms strobes, than with 2.4ms strobes.

So this is further proof you are correct, that we need a [email protected] display someday this century (one can hope!) — because 1.4ms is equivalent to 1/700sec, and having 1/1000sec display samples is quite close; at 10%, LightBoost is doing roughly equivalent to a 5:1 black frame insertion via backlight means (1.4ms:6.9ms bright:dark during an 8.3ms refresh cycle).

LightBoost displays actually partially framebuffer the refresh and does an accelerated scanout (~1/200sec or ~1/240sec) to artificially create a longer vertical blanking interval for a longer pixel-settling time before strobing the backlight. Then it also uses a Y-axis-compensated response-time-acceleration algorithm, to compensate for the difference in the freshness of the pixels at the top edge versus bottom edge (since the LCD scanouts in the total darkness). Marc Repnow (of did some reverse engineering of the LightBoost behavior, and some TestUFO patterns (e.g. blur trail using blue/yellow) revealed evidence of “RTC zones” along the vertical axis. We even discovered that LightBoost strobe backlight is strobed very late into the VSYNC, and the backlight is still ON when the next refresh begins (turning off about 0.5ms into the next refresh), this is because LCD pixels of the next refresh haven’t yet noticeably begun transitioning. Strobe backlight experiments need a phasing control (to control the timing of strobes relative to VSYNC), as it apparently is beneficial to make the flash as late as possible, and last slightly into the next refresh when transitions are still invisible. (this creates more time for the previous refresh’ pixels to settle).

One needs a fast scanout, followed by a very long VSYNC, for a strobe backlight. And the design of a Y axis variable into the RTC math calculations, will benefit reduction of vertical-axis-asymmetric ghosting artifacts (e.g. increased ghosting along the top/bottom edge).
Quote:
Originally Posted by Michael Abrash @ Valve Software 
July 30, 2013 at 9:11 pm
Interesting stuff! One thought: You can strobe as fast as you want, but current LCDs can’t transition at anywhere near 1000 Hz, and that’s going to be a limiting factor with LCDs for a long time, even if a video channel capable of anywhere near that bandwidth becomes available.

–Michael
Quote:
Originally Posted by Mark Rejhon 
July 31, 2013 at 9:35 am
For current LCD’s, yes, this will limit your strobe Hz to be longer than the pixel’s ability to transition.

Currently, reducing the contrast of the LCD (e.g. reducing VG278H to about 50%-60%) also increases overdrive headroom so that ghosting and 3D crosstalk falls completely below human-perceptible levels (even along bright vertical edges). You can strobe quicker, but you start to get more and more inter-refresh crosstalk the more you “eat” into the next LCD refresh.

The active-matrix OLED’s won’t be fast enough for [email protected], but passive-matrix OLED are definitely fast enough. Problem is passive-matrix isn’t practical for good brightness on a large-size high-def OLED. This may change (e.g. science lab stuff, such as parallel multiscanning an AMOLED to allow the bandwidth needed for 1000Hz)

We can all hope for Plan B. Blue-phase LCD’s: 10 to 100 microseconds! Enough for [email protected] eventually. This was published in the journal of Society for Information Display (google “blue-phase LCD”. Those can transition in microseconds and they’ve already demonstrated color-sequential LCD’s using this this tech. Color sequential; imagine that — just like DLP.

Interesting Blur Busters history note: Blur Busters Blog started all because of John Carmack's tweet reply to me.
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post #3 of 42 Old 08-03-2013, 06:46 AM
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Isn't that just for 1080p?
Quote:
although higher frame rates would be required to hit the sweet spot at higher resolutions
What about the optimal fps for 4K and 8K?
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post #4 of 42 Old 08-03-2013, 11:12 AM
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I don't know if you've seen it yet, but there was some discussion of this and Valve's research in John Carmack's keynote at QuakeCon. (and your original project with the LED strips got a mention as well)
There was talk of using time warping and frame interpolation inside the game engine to help achieve these kinds of framerates.

If you haven't seen it, here's a demo from a few years back, using interpolation to go from 30fps to 60fps in the game engine: http://and.intercon.ru/releases/talks/rtfrucvg/
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post #5 of 42 Old 08-03-2013, 08:18 PM - Thread Starter
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Quote:
Originally Posted by Joe Bloggs View Post

Isn't that just for 1080p?
What about the optimal fps for 4K and 8K?
There are a lot of variables, so there's no single answer.

The more resolution you have, the more pixels of motion blur you get at the same angular motion. The angular motion blur is the same, but since the angular motion covers more pixels (more density), you're not hitting the necessary sweet spot of less than 1 pixel of motion blur for fast panning to look exactly as sharp as stationary images to the human eye. The visual acuity of the human eye also plays a role, so beyond a certain point, it doesn't matter, but as long as individual pixels are big enough to be resolved, Mike's correct that you need higher Hz for higher resolution, to keep "pixels-of-motion-blur" the same for the same angular motion speed, and if you're trying to hit the sweet spot of less than 1 pixel of motion blur (imperceptible), there you go... (e.g. strafing and turns in games, as well as when turning your head using VR goggles as Michael Abrash was talking about) This is talked about by John Carmack at about 12mins into his YouTube.

For moderately fast motion of 960 pixels per second, CRT's (and LightBoost 10%) manages to hit the motion clarity sweet spot where http://www.testufo.com/#test=photo *AND* http://www.testufo.com/#test=photo&pps=0 have exactly the same sharpness either moving or stationary (no judder, no stutters, no streaking, no blur, no ghosting, no overdrive).

Even at [email protected], you can mathematically still have human-perceptible motion blur during high-def computer graphics moving at 2000 pixels/second if your eyes are able to track that fast *AND* the pixels themselves are resolvable. Since 1ms equals 1 pixel of motion blur for every 1000 pixels per second, since your eyes have tracked 1/1000th that distance, causing that pixel to smear. If one pixel is big enough to be resolvable, then blur will be noticed in that pixel if the eye tracking accuracy is good enough and the motion is fast enough. At 2000 pixels/sec, there is 2 pixels of blur at [email protected] sample-and-hold, so even that might still not be the final frontier; it's still a finite-refresh display with diminishing returns, but not disappeared returns required for HoloDeck quality.

Some people may be familiar with the Blur Busters pursuit camera tests at PHOTOS: 60Hz vs 120Hz vs LightBoost, which actually surprisingly corresponds well with what the human eye sees when directly viewing the ghosting pattern at www.testufo.com/#test=ghosting

But head turning at only 30 degrees per second on a 1080p VR googles, the motion blur becomes immediately noticeable in fast pans (much like the motion blur at www.testufo.com/#test=photo which on modern LCD's the motion blur is caused by eye tracking, not by the display response speed.) because it envelopes your vision and your head turns forces panning (a motion blur torture test case).

Not everyone does eye-tracking during fast motion on screen. But the problems of discrete-framerate (even at 240, 480, 960) displays conflicting with the non-framerate nature of human eyes -- this problem becomes noticeable during head-turning in VR -- or when people use computer monitors at close-distances and want fast FPS gaming (strafing/turning) to be as perfectly sharp as stationary images.

There are scientific extreme cases where, humans would notice non-Holodeck-perfect limitations at beyond [email protected], due to the stroboscopic effect / wagon-wheel effect, but generally speaking, [email protected] woiuld probably eliminate the vast majority of problems for Holodeck-like simulations. You could intentionally add 1 millisecond of motion blur (which is tiny) to fix any remaining stroboscopic/wagonwheel effect problem of discrete-refresh displays, and the motion blur increment would be small enough to not be objectionable except during the fastest head turning.

Mathematically, 1ms equals 1 pixel of eye tracking motion blur with display motion of 1000 pixels/second (1 pixel per millisecond)
(Assuming pure strobes -- on then off, no decay trails, no aftereffects, no sample-and-hold beyond this time)

-- How big are the pixels? 2K vs 4K vs 8K
-- How sharp is the source material? Unfiltered computer graphics is easier to see blur in, than during video.
-- How fast is the panning? Faster panning creates more eye-tracking motion blur on displays.
-- How fast can you track your eyes accurately? That defines your upper limit when pans are too fast for eyes to track. (That's the moment of sweet spot)
-- How accurate is your eye tracking? (saccade factor) Different people are much more accurate at eye tracking, the shiftiness/jerkiness of the eyeball motion.
-- How much angular vision is covered? It's easier to notice motion blur in faster pans in wider displays that span your vision, because you have more time to track eyes accurately.
-- Etc. Other variables exist.

All the study of Vision Research stuff (e.g. people who use www.vpixx.com products and similar)
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post #6 of 42 Old 01-14-2014, 11:53 AM - Thread Starter
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More 1000fps talk, in interview with Oculus:

http://venturebeat.com/2014/01/14/oculus-vrs-brendan-iribe-on-the-virtual-reality-prototype-interview/
Quote:
You could avoid low persistence if you could run the screen at a few thousand hertz and only have, say, one millisecond of time between frames. But that’s not practical to tell game developers, “Hey, if you want to make VR games, you have to run at 1,000 FPS.” We want to say, “You can make great virtual reality, and you only need to run at 40, 50, 60 on your game engine.” The rendering engine will need to run a little bit faster, in sync with the refresh rate of the screen. But it’s very practical. People shouldn’t have too hard a time with where they are today.

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post #7 of 42 Old 12-26-2017, 12:46 PM - Thread Starter
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Update (New Year's 2018)

I have written a much, much more comprehensive follow-up to this article. As the co-author of a peer-reviewed conference paper on a display testing technique (along with NOKIA, NIST.gov and Keltek researchers), I've begun writing new content that covers this topic.

This is the journey towards blurfree sample-and-hold. Flickerless low persistence. Blurfree without strobing or black frame insertion. Strobeless ULMB technologies. A completely flickerless method of display motion blur reduction -- this requires ultra-high refresh rates. This will be extremely important for virtual reality, but also important for large gaming displays too as well.

Blur Busters Law: The Amazing Journey To Future 1000Hz+ Displays
(December 24, 2017)

The good news is that such crazy-high true native Hertz (not faked "600 Hz" or other) is coming within our lifetimes now. I was the world's first person to do an end-user test a true-480Hz monitor and now I'm writing about 1000Hz -- I now conservatively expect mainstream 480Hz eSports gaming monitors by ~2020 and also 1000Hz gaming monitors by ~2025.
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post #8 of 42 Old 12-27-2017, 08:03 AM
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Thanks for sharing this. Much appreciated.

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post #9 of 42 Old 12-27-2017, 08:29 AM
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I see (and understand why) a lot of space is dedicated, in your latest article, to VR uses. As a "regular" TV watcher I'm wondering: where would the point where OLED manages to give a visual experience similar to plasma and CRTs with their curved strobing? Even more specific: what is the solution we must be looking for if what we want is 24fps movie content being played back with the same visual experience we had on plasma? From all I'm reading we are not there. My Kuro internally displays 24fps content at 72Hz and I'm satisfied with that in the majority of cases. What's the deal with OLED to get that result? Is the current internal 120Hz enough, considering that they have square-waved strobing?
Or... re-reading what you wrote: TVs are currently not strobing in any way? I'm now wondering whether what I just wrote applies to the typical scenario here at AVS.

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You're still relying on the subjective motion impressions of the most critical viewers here? How about all of those who have acclimated to current OLED motion after years of plasma? Shouldn't their accounts hold some value? Is there still no way for you to experiment with one for yourself? Life's short as the years drone on, and the quote in your signature is ironic. There were no motion changes in the LG lineup between 2016 and 2017 (nor 2015 and perhaps even earlier), so chances are 2018 promises more of the same.

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post #11 of 42 Old 12-27-2017, 10:09 AM
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Quote:
Originally Posted by gorman42 View Post
Even more specific: what is the solution we must be looking for if what we want is 24fps movie content being played back with the same visual experience we had on plasma?
Plasma.


Quote:
Originally Posted by gorman42 View Post
What's the deal with OLED to get that result? Is the current internal 120Hz enough, considering that they have square-waved strobing?
It looks pretty bad and obviously strobes.

OLED is the future of displays (perhaps to compete with ILED), and the problem will be solved with future content, specifically with HFR.

It's too late to hope for mandatory HFR for SHV (Were it up to me, I would've deprecated sub-60p modes for 8K content. What's the point of more pixels if you can't see them?), but there's always something next.

As for old movies, I would hope for AI-assisted HFR remastering. It won't be as good as native 60p-120p, much of that motion resolution is already lost in the shutter, but it will be way better than what that $50 cell phone CPU in the TV can spit out in real time.
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post #12 of 42 Old 12-27-2017, 10:16 AM
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Give me quality crapless panel at 4K 120-144hz i mean fps and i take it!!!!
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post #13 of 42 Old 12-28-2017, 06:55 AM
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Quote:
Originally Posted by video_analysis View Post
You're still relying on the subjective motion impressions of the most critical viewers here? How about all of those who have acclimated to current OLED motion after years of plasma? Shouldn't their accounts hold some value? Is there still no way for you to experiment with one for yourself? Life's short as the years drone on, and the quote in your signature is ironic. There were no motion changes in the LG lineup between 2016 and 2017 (nor 2015 and perhaps even earlier), so chances are 2018 promises more of the same.
I'm not getting your point. I'm simply trying to get information, which is, I believe, one of the main reasons for this forum's existence. I'm not "postponing" buying an OLED TV while hoping for perfect motion. I've postponed so far for the simple reason that OLED TVs were too expensive for my finances (considering I still own a decent and functioning Kuro TV).

Quote:
Originally Posted by AnalogHD View Post
Plasma.
Hrmmm... it's an answer I guess. Not what I was hoping for but still... an answer.

Quote:
OLED is the future of displays (perhaps to compete with ILED), and the problem will be solved with future content, specifically with HFR.

It's too late to hope for mandatory HFR for SHV (Were it up to me, I would've deprecated sub-60p modes for 8K content. What's the point of more pixels if you can't see them?), but there's always something next.

As for old movies, I would hope for AI-assisted HFR remastering. It won't be as good as native 60p-120p, much of that motion resolution is already lost in the shutter, but it will be way better than what that $50 cell phone CPU in the TV can spit out in real time.
As much as I like the hope for "future content", it seems to me we are *very* far from native HFR content being widespread. Personally I watched The Hobbit in HFR and I did not like it at all. As such, I'd like info on what might be the "perfect" solution for proper reproduction of movie content (24fps). I'd be all for HFR or Super HFR (120fps+) for sports, though.

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Doesn't OLED's 0.2ms responce time and 120hz already eliminate most of the blurr problems on PC?
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Doesn't OLED's 0.2ms responce time and 120hz already eliminate most of the blurr problems on PC?
You really need to read the article linked here to understand why that's not the case.

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Doesn't OLED's 0.2ms responce time and 120hz already eliminate most of the blurr problems on PC?
Alas, 120fps only halves motion blur on sample-and-hold displays.
To reduce blur further, you need to do more, either via either (A) or (B).
(A) Strobe backlight (black frame insertion)
(B) Ultra high refresh rates.
(C) A combination of the two
(i.e. use 120Hz instead of 60Hz to reduce flicker, then use strobing to reduce persistence further)


ULMB is an NVIDIA-developed strobe backlight mode in gaming monitors, that achieves sub-2ms persistence, via a strobe backlight that flashes once per refresh cycle to shorten frame visibility time to reduce eye-tracking-based motion blur (animation demo)

Strobe backlights achieve 2ms persistence via a 2ms flash. To achieve the same motion clarity without flicker (no black frames) you need to fill all 2ms timeslots in a second, aka [email protected]

With impulsing (strobing/flicker/BFI)
120Hz full persistence (8.3ms) = 8.3 pixels of motion blur at 1000 pixels/sec
120Hz at 4ms flash = 4 pixels of motion blur at 1000 pixels/sec
120Hz at 2ms flash = 2 pixels of motion blur at 1000 pixels/sec
120Hz at 1ms flash = 1 pixels of motion blur at 1000 pixels/sec

Flickerfree sample-and-hold
8.3ms persistence = (1000/8.3) = 120fps (at 120Hz+) = 8.3 pixels of motion blur at 1000 pixels/sec
4ms persistence = (1000/4) = 250fps (at 250Hz+) = 4 pixels of motion blur at 1000 pixels/sec
2ms persistence = (1000/2) = 500fps (at 500Hz+) = 2 pixels of motion blur at 1000 pixels/sec
1ms persistence = (1000/1) = 1000fps (at 1000Hz+) = 1 pixels of motion blur at 1000 pixels/sec

This is why CRT was always so sharp, the display flickered briefly with lots of dark between refresh cycles. No motion blur differences between refresh rates on a CRT. But for LCDs, doubling refresh rates often halves motion blur (as long as most of the LCD GtG curve is a tiny part of a refresh cycle)

Motion blur is individual frame visibility time. More scientific information is explained at www.blurbusters.com/1000hz-journey

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As much as I like the hope for "future content", it seems to me we are *very* far from native HFR content being widespread. Personally I watched The Hobbit in HFR and I did not like it at all. As such, I'd like info on what might be the "perfect" solution for proper reproduction of movie content (24fps). I'd be all for HFR or Super HFR (120fps+) for sports, though.
And games. And virtual reality.

In virtual reality, motion blur creates lots of headaches and nausea. Everytime you turn your head, the screen pans, and everything is a blurry mess. You can't read street name labels on a panning map animation even on a 120Hz LCD without strobing. It's still too much persistence.

That's exactly what you see, in older (high persistence) virtual reality, if you stare at a street map taped to a virtual wall in virtual reality, while slowly nodding your head around. All that continuous screen-panning in a VR headset's screen, creating motion blur, makes low-persistence absolutely critically essential for good virtual reality (and future holodecks). You do not want additional display-induced motion blur forced upon your eyes, above-and-beyond natural human-vision motion blurring, when you're walking around in a Holodeck-like environment.

It's also useful for TV sports, immersive games, and people who love HFR content.

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As much as I like the hope for "future content", it seems to me we are *very* far from native HFR content being widespread. Personally I watched The Hobbit in HFR and I did not like it at all. As such, I'd like info on what might be the "perfect" solution for proper reproduction of movie content (24fps). I'd be all for HFR or Super HFR (120fps+) for sports, though.
I took a preview of some implementations of artificial-intelligence video processing at CES 2018 and I must admit, it looked darn good on a lot of material. No framerate slowdowns, at least on the demo material I saw. There were times where parallax-reveal effects were flawless (successful guessing of background-reveals) and it looked like genuine 120fps HFR video. This is not your grandfather's fake-looking Motionflow Soap Opera Effects anymore (just HFR-style resmoothness).

Obviously, good old fashioned 24fps with the CRT-like/plasma-like strobing, can be an acquired preference, much like the double-strobe (48Hz flicker) of old film projectors. Not everyone likes old 24fps film converted to the "HFR look", although this is less prevalent amongst millenials (anecdotally).

Such "old school 24fps double-strobed look (or triple strobed)" is not very easy to reproduce, unless you had an OLED with a rolling-scan mode that could run at ~72 Hz for a triple-strobe that looked similar to plasma. Also the phosphor fade (CRT, plasma) modifies the motion blur of film-watching, so motion appearance is slightly different from squarewave-like pulsing available with strobe backlights (on fast-GtG LCDs) and rolling-scan OLEDs. Another factor to consider for trying to mimic the blur trail of old-school 35mm projectors. Certainly can respect such a user preference.

That said, an optional low-persistence mode should always be added to future OLEDs to allow us to watch material without any display motion blur forced up on our eyes above-and-beyond content blur (camera blur, etc) or human blur (natural vision blurring).

It should always be a choice made available to users like us, instead of permanent (unadjustable) display motion blur.

Why this matters is a lot more important for VR, but also important to people who hate both flicker and blur. Basically, wishing that you can get blurfree of CRT, with the flickerfree of LCD. It's possible -- just takes Hertz insanity to merge the two completely for five-sigma population (including all vision sensitivities).

Strobing (flicker) is just a band-aid and it was a bonus feature of CRT/plasma, but good riddance to flicker -- it's better to use blurless sample-and-hold which is closer to real life. Real life does not strobe.
Currently, blurless sample-and-hold is only found in the laboratory (experimental true-1440Hz and true-1700Hz displays, etc) but will filter out eventually within one human generation or so.

After 8K went darn virtually "retina" the next big Display "Moore's Law" will be refresh rates through to the 2020s-2050s since there's still lots left in the "diminishing points of return" curve. I expect refresh rates of premium gaming monitors to double once every 5 years for the forseeable future (to the true-1000Hz era by around year 2025). The only way to do CRT-clarity via sample-and-hold (NO light modulation/flicker/strobe/flash/scanning flash/phosphor decay) is via quadruple-digit refresh rates, due to law of physics.

And the quadruple-digit true refresh rates, coming within a human generation (but already in laboratories toda) also fixes a lot of stroboscopic issues without being forced to add blur to images. No camera blur, no display blur, no GPU blur effects, these are verboten for virtual reality due to headaches/nausea. And not everyone can stand flicker even at high Hz.

As said before, for VR you don't want added motion blur above-and-beyond natural human vision limits. That said, it also has great spinoff applications for the simultaneously "blur-sensitive" and "flicker-sensitive" individuals. People who can't stand CRT due to flicker, can't stand LCD due to blur. Or just someone who'd love a display that can simultaneously eliminate display motion blur and stroboscopic effects.



(I was the first person in the world to test true-480Hz via a high-end-mainstream perspective -- true 480Hz, not fake 480Hz)
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Thanks for all the info. You might be aware that LG is introducing BFI to their 2018 OLED lineup. The panels work natively at 120Hz. How do you think that could improve the 24fps material situation, as far as motion reproduction is concerned, when compared to plasma? Will it show improvements (accepting the reduction in general light output)?

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Thanks for all the info. You might be aware that LG is introducing BFI to their 2018 OLED lineup. The panels work natively at 120Hz. How do you think that could improve the 24fps material situation, as far as motion reproduction is concerned, when compared to plasma? Will it show improvements (accepting the reduction in general light output)?
For plasma-outperforming blur free sports
120Hz+BFI is the sweet spot for current pssible state of tech progress.

The first OLED to successfully combine 120Hz+BFI simultaneously, with at least a 75% black duty cycle (3:1 ratio BFI), while not being too dim, will be the first one to greatly outperform plasma in sports material.

Alas, yes, that means combining interpolation and BFI to solve the blur problem without eye-searing flicker. But intelligent AI interpolation finally make it look like true HFR. One you throw a multi-teraflops GPU/ASIC at the interpolation fakeness problem, the real magic finally happens with that overkill. For the first time, I can tolerate interpolation as a compromise since it now finally looks like true native frame rate nearly all the time. The best plasmas tended to use interpolation too, for motion-compensated subfield refreshes (e.g. Panasonic) so we're not losing anything, anyway.

For 24fps original film look
Now for 24fps material, five-strobe [email protected] doesn't mimic double-strobe 48fps very accurately. Hopefully LG added an optional 72Hz NON-interpolated triple strobe mode, as a compromise for film-lovers preferring the old-35mm-motionfeel almost as good as 48Hz-double-strobe, but without the 48Hz flicker.

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For plasma-outperforming blur free sports
For 24fps original film look
Now for 24fps material, five-strobe [email protected] doesn't mimic double-strobe 48fps very accurately. Hopefully LG added an optional 72Hz NON-interpolated triple strobe mode, as a compromise for film-lovers preferring the old-35mm-motionfeel almost as good as 48Hz-double-strobe, but without the 48Hz flicker.
I currently still own a Kuro. As far as I remember, its Advanced Cinema setting ran the panel at 72Hz (no BFI obviously). You think LG should do the same with OLED? Running the panel at 72Hz to show each frame three times?

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I currently still own a Kuro. As far as I remember, its Advanced Cinema setting ran the panel at 72Hz (no BFI obviously). You think LG should do the same with OLED? Running the panel at 72Hz to show each frame three times?
Well, 144Hz with every other frame being black.

That would emulate the look of a film projector, for what it's worth.
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Well, 144Hz with every other frame being black.

That would emulate the look of a film projector, for what it's worth.
Yeah... well, they can't do that, given that the panel has a max 120Hz refresh rate.

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I currently still own a Kuro. As far as I remember, its Advanced Cinema setting ran the panel at 72Hz (no BFI obviously).
Both CRT and plasma had phosphor decay, which behaves scientifically similar to BFI. BFI-equivalence ratios are pretty huge for CRT (due to rapid phosphor fade) and a little less for plasma.

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Yeah... well, they can't do that, given that the panel has a max 120Hz refresh rate.
You can do a modified double-strobe algorithm by using a BFI cycle of ON-OFF-ON-OFF-OFF with [email protected] But that produces a worse flicker.

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You think LG should do the same with OLED? Running the panel at 72Hz to show each frame three times?
144Hz, to make room for BFI type algorithms. Unless you ran it as a form of a resizeable rolling scan algorithm rather than granular-refresh-cycle-based BFI.


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Both CRT and plasma had phosphor decay, which behaves scientifically similar to BFI. BFI-equivalence ratios are pretty huge for CRT (due to rapid phosphor fade) and a little less for plasma.


You can do a modified double-strobe algorithm by using a BFI cycle of ON-OFF-ON-OFF-OFF with [email protected] But that produces a worse flicker.


144Hz, to make room for BFI type algorithms. Unless you ran it as a form of a resizeable rolling scan algorithm rather than granular-refresh-cycle-based BFI.

So if I understand, with true 'simple' BFI (full-frame blanking), you are limited to increments if the down-sampled native panel refresh rate (ie: a 120fps panel is limited to 50% @ 60fps; 33% or 67% @ 40 fps; 75%, 50%, or 25% @ 30fps; and 80%, 60%, 40%, or 20% @ 24fps), while using an LCD-scanning-backlight-like raster-style refresh with blanking (advanced BFI), you can have finer level of control all the way down to whatever maximum blanking allows you to deliver the minimum brightness you require (brightness decreased by decreased persistance rather than decreased peak lumens). Is this correct?

And one other question I have is do you understand the nature/cause for the 'Soap Opera Effect'? How would 1000fps interpolation and 1ms persistance avoid some viewers perceiving 'super SOE'? (what is the mechanism / cause for SOE?)
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So if I understand, with true 'simple' BFI (full-frame blanking), you are limited to increments if the down-sampled native panel refresh rate (ie: a 120fps panel is limited to 50% @ 60fps; 33% or 67% @ 40 fps; 75%, 50%, or 25% @ 30fps; and 80%, 60%, 40%, or 20% @ 24fps)
Correct. Refresh-cycle based "BFI" is limited to refresh cycle granularity.

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while using an LCD-scanning-backlight-like raster-style refresh with blanking (advanced BFI), you can have finer level of control all the way down to whatever maximum blanking allows you to deliver the minimum brightness you require (brightness decreased by decreased persistance rather than decreased peak lumens). Is this correct?
Correct. Rolling-scan "BFI" (scanning backlights, OLED rolling scans) can be a resizeable window independent of refresh cycle length.

And full-strobe backlights (Found in gaming monitors: LightBoost, ULMB, ELMB, DyAc), since they tend to be superior in some ways to scanning backlights in generating "persistence = MPRT = strobe length" due to lack of internal backlight diffusion. But those full-strobe LCD backlights require GtG fast enough to squeeze into the VBI (interval between refresh cycles) so full-strobe only works well when LCD GtG is very fast and correctly-overdriven. Otherwise, you get lots of strobe crosstalk.

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And one other question I have is do you understand the nature/cause for the 'Soap Opera Effect'? How would 1000fps interpolation and 1ms persistance avoid some viewers perceiving 'super SOE'? (what is the mechanism / cause for SOE?)
I will link to this post that I made in the OLED Tech Thread.

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I make a distinction between SOE versus SOE artifacts. Two different subjects.
SOE = the super smooth motion.
SOE artifacts = flaws/fakeness in the super smooth motion.

Many confuse the two. I don't mind SOE for sports, but I hate SOE artifacts (e.g. edge distortions). Proper, good, modern, powerful interpolation can solve a lot of SOE artifacts. Also, not everyone can tell apart SOE and SOE artifacts. For example, SOE combined with motion blur (since cameras has motion blur) can look rather fake, instead of real life. But on the other hand, that's not SOE's fault, but the camera's fault.

Motion blur can be artistically nice sometimes -- but if you're trying to pass a Holodeck Turing Test (reality test), you don't want additional motion blur forced upon your eyes above-and-beyond natural human vision. So to make things real looking, the camera shutter should be 1/1000sec or shorter for video (any frame rate) delivered to an interpolator designed for a [email protected] display.

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Correct. Refresh-cycle based "BFI" is limited to refresh cycle granularity.


Correct. Rolling-scan "BFI" (scanning backlights, OLED rolling scans) can be a resizeable window independent of refresh cycle length.

And full-strobe backlights (Found in gaming monitors: LightBoost, ULMB, ELMB, DyAc), since they tend to be superior in some ways to scanning backlights in generating "persistence = MPRT = strobe length" due to lack of internal backlight diffusion. But those full-strobe LCD backlights require GtG fast enough to squeeze into the VBI (interval between refresh cycles) so full-strobe only works well when LCD GtG is very fast and correctly-overdriven. Otherwise, you get lots of strobe crosstalk.


I will link to this post that I made in the OLED Tech Thread.
Thanks for the reply.

I'm most interested in how Rolling-scan BFI can be used to best improve WOLEDs motion performance.

If I'm understanding you correctly, other than implementing good interpolation to 120fps, the only other thing they can do is reduce persistance to the minimum.

Currently, effective brightness effectively dims when full-frame BFI is engaged. Since energy consumption is equivalent, LG would be better off increasing brightness to max whenever BFI is engaged and lowering brightness by reducing persistance interval.

LG's 2017 WOLEDs can apparently put out 700 cd/m2 so if I prefer to watch in the dark at 120cd/m2 peak, I should be able to engage ~ 80% blanking (so petsistance is reduced from 8.3ms to 1ms at 120fps).

From what you wrote in the Technology Thread, 120fps with 1ms persistence should be 'yummy' (very good motion performance).

80% blanking from 24fps sources is easy (4 black frames inserted for each source frame) but I think you said the flicker would be very noticable, so some interpolation is needed (at which point rolling-scan BFI would also be needed).

If a full cinema frame was decomposed into 5 horizontal segments (with the rest of the frame black) and these are fed in sequence at 120fps (at max brightness)' the result should be a 'cheap-and-dirty' rolling-scan BFI that reduces persistance from 42ms to 8.3ms.

This is probably about the best that can be done without interpolation (and with todays peak WOLED brightness levels), would you agree?

60fps OTA sports can use 50% Full-Frame BFI to reduce persistance from 16.7ms to 8.3ms (which is probably what LG has implemented) but with interpolation and a true rolling-scan backlight, they could reduce persistance to 4ms or even 2ms (not enouh peak brightness to reduce persistance to 1ms, at least not with lights on ).

I have no idea whethet WOLED offers a way to 'turn-off' and 'turn-on' individual lines or segments of lines without losing data (and thus requiring a refresh), but if so it seems like that capability is actually more important than (further) increased framerate.

The key is having LG realize that they should be using all of that 'extra' HDR peak bightness to improve the motion performance of SDR...

What do we need to do to get you invited to LG to give their engineers a presentation
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post #27 of 42 Old 01-18-2018, 05:02 PM - Thread Starter
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Thanks for the reply.

I'm most interested in how Rolling-scan BFI can be used to best improve WOLEDs motion performance.

If I'm understanding you correctly, other than implementing good interpolation to 120fps, the only other thing they can do is reduce persistance to the minimum.

Currently, effective brightness effectively dims when full-frame BFI is engaged. Since energy consumption is equivalent, LG would be better off increasing brightness to max whenever BFI is engaged and lowering brightness by reducing persistance interval.
Yes. On certain low-persistence displays, sometimes the "Brightness" adjustment adjusts the ULMB pulse width, meaning lower brightnesses have lower persistence too. Other times, this is a separate adjustment (e.g. "ULMB Pulse Width" found on NVIDIA G-SYNC monitors with ULMB).

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LG's 2017 WOLEDs can apparently put out 700 cd/m2 so if I prefer to watch in the dark at 120cd/m2 peak, I should be able to engage ~ 80% blanking (so petsistance is reduced from 8.3ms to 1ms at 120fps).
In theory, yes. Realistically, it requires an OLED with two simultaneous scanout channels (one to scan-out the pixels, and another to turn-off the pixels). If the OLED only has one scanout channel, you can only do full-refresh-cycle granularity BFI.

Also, if OLED GtG curves aren't perfect enough (they're fast, but not instant). Shorter rolling scan windows can begin to distort colors at shorter persistences. 1ms persistence with 0.01ms GtG differences between the colors can inject noticeable color-shift errors (1% color difference = 1ms/0.01ms) so the more the persistence falls closer to GtG differentials between the colors, the more difficult to keep the colors balanced and artifact-free. You need really fast OLED GtG, that are symmetric between all colors for good low-persistence via tight rolling-scan windows.

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From what you wrote in the Technology Thread, 120fps with 1ms persistence should be 'yummy' (very good motion performance).
Yes, 120Hz is relatively flicker free for most people. Pure 1ms persistence 120Hz (via ~80-85% BFI using strobing or rolling scan) can generate clearer and sharper motion than a 600Hz plasma (yes, even the Kuro). Assuming the OLED GtG was sufficiently fast enough to be problem-free with 1ms rolling scans.

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80% blanking from 24fps sources is easy (4 black frames inserted for each source frame) but I think you said the flicker would be very noticable, so some interpolation is needed (at which point rolling-scan BFI would also be needed).
Yes, 24Hz flicker is too painful for most. Some people can get used to it, but I wouldn't recommend it -- it can be epileptic.

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Originally Posted by fafrd View Post
If a full cinema frame was decomposed into 5 horizontal segments (with the rest of the frame black) and these are fed in sequence at 120fps (at max brightness)' the result should be a 'cheap-and-dirty' rolling-scan BFI that reduces persistance from 42ms to 8.3ms.
It may flicker less, but you'll get tearing artifacts if you try to do that.

Like VSYNC OFF, but with 4 stationary tearlines during horizontal panning.

Pure BFI is better (for [email protected] you can play with ratios, like 4:1, 3:2, 2:3, or 1:4).

Quote:
Originally Posted by fafrd View Post
60fps OTA sports can use 50% Full-Frame BFI to reduce persistance from 16.7ms to 8.3ms (which is probably what LG has implemented)
I am genuinely hoping it's 120Hz full frame BFI -- essentially 4.2ms persistence. Fingers crossed. But I haven't seen this in operation yet. I should ask LG.

Quote:
Originally Posted by fafrd View Post
but with interpolation and a true rolling-scan backlight, they could reduce persistance to 4ms or even 2ms (not enouh peak brightness to reduce persistance to 1ms, at least not with lights on ).
Yes, indeed. Also, don't forget that internal diffusions in a scanning backlight will always increase persistence. Scanning backlights often don't achieve MPRT persistence identical to scanning-backlight-segment flash lengths because of light bleed/diffusion. Only strobe backlights do, and fast-GtG rolling-scan OLEDs tend to have persistence (MPRT) matching pixel pulse length.

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Originally Posted by fafrd View Post
I have no idea whethet WOLED offers a way to 'turn-off' and 'turn-on' individual lines or segments of lines without losing data (and thus requiring a refresh)
OLEDs don't quite work that way. On current OLEDs, turning on the pixel is the same thing as refreshing the pixel: You're telling the pixel to turn on to a specific color. OLED pixels currently do not have memory.

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Originally Posted by fafrd View Post
The key is having LG realize that they should be using all of that 'extra' HDR peak bightness to improve the motion performance of SDR...
Yes, high HDR peak brightness is great headroom for low-persistence SDR.
The 10,000nit Sony demo display could reduce persistence by 90% while still having 1,000nits left!

Quote:
Originally Posted by fafrd View Post
What do we need to do to get you invited to LG to give their engineers a presentation
They're already (slowly) beginning to figure it out.

Blur Buster articles are often read by monitor engineers, and the Area51 forum also get many hits from the offices of the manufacturer domain names in my weblogs. Whether my display motion blur photography pursuit camera invention or the free strobe backlight engineering howto, and many others, the free Blur Busters articles already has help fix gaming monitor manufacturers improve their monitors (strobe fixes, frame skipping fixes, etc) -- numerous firmware upgrades have been blamed on me!

Blur Busters writings helped introduce strobe backlights into more monitors. Also, sometimes I test displays for them. I tell them what's wrong with the display (fixable bugs), and they send a new firmware to fix it -- or even a replacement gaming monitor with the new firmware precisely because of my bug report. Such as frameskipping fixes, strobe timing/phase fixes (fewer double-images), etc.

While I have contacts at gaming monitor manufacturers (some of which now outperform plasma in motion clarity for 120fps HFR material), I do not currently have much catchet with television manufacturers, but I'm eventually going to work to change that.
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post #28 of 42 Old 01-19-2018, 07:47 AM
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I'm sorry could you explain the difference between "refresh-cycle based BFI" and "rolling-scan based BFI"? You talk about OLED "rolling scans" and I lose you...

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post #29 of 42 Old 01-19-2018, 12:04 PM
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Quote:
Originally Posted by Mark Rejhon View Post
Yes. On certain low-persistence displays, sometimes the "Brightness" adjustment adjusts the ULMB pulse width, meaning lower brightnesses have lower persistence too. Other times, this is a separate adjustment (e.g. "ULMB Pulse Width" found on NVIDIA G-SYNC monitors with ULMB).


In theory, yes. Realistically, iit requires an OLED with two simultaneous scanout channels (one to scan-out the pixels, and another to turn-off the pixels). If the OLED only has one scanout channel, you can only do full-refresh-cycle granularity BFI.

Also, if OLED GtG curves aren't perfect enough (they're fast, but not instant). Shorter rolling scan windows can begin to distort colors at shorter persistences. 1ms persistence with 0.01ms GtG differences between the colors can inject noticeable color-shift errors (1% color difference = 1ms/0.01ms) so the more the persistence falls closer to GtG differentials between the colors, the more difficult to keep the colors balanced and artifact-free. You need really fast OLED GtG, that are symmetric between all colors for good low-persistence via tight rolling-scan windows.
Do you know the GtG for LGs WOLEDs? What is the practical lower-persistsnce limit you believe LGs current-generation of WOLED technology can achieve without introducing GtG-related color shift?


Quote:
Yes, 120Hz is relatively flicker free for most people. Pure 1ms persistence 120Hz (via ~80-85% BFI using strobing or rolling scan) can generate clearer and sharper motion than a 600Hz plasma (yes, even the Kuro). Assuming the OLED GtG was sufficiently fast enough to be problem-free with 1ms rolling scans.


Yes, 24Hz flicker is too painful for most. Some people can get used to it, but I wouldn't recommend it -- it can be epileptic.
I'll take my movie watching without epileptic seizures, thank you !!!

So it sounds like for 24fps cinema, simulating a shutter with full-scrren blanking at 4:1, 3:2, 2:3, or 1:4 is the best that can be done. I hope LG has offered that control. If not, once their 2019 HDMI2.1 WOLEDs emerge, this could always be done by the bluray player or a converter box.

To do this right, it shoukd be done in the TV and should increase brightness in inverse to the blanking % (up to maximum brighness and then the picture starts to dim).

Quote:

It may flicker less, but you'll get tearing artifacts if you try to do that.

Like VSYNC OFF, but with 4 stationary tearlines during horizontal panning.

Pure BFI is better (for [email protected] you can play with ratios, like 4:1, 3:2, 2:3, or 1:4).
Got it.

Quote:
I am genuinely hoping it's 120Hz full frame BFI -- essentially 4.2ms persistence. Fingers crossed. But I haven't seen this in operation yet. I should ask LG.
Would be great if you would. Since they currently have no way to feed 120fps video into the TV, I won't be surprised to see that they've impkemented this first-gen BFI in the 'easy' way of using 120fps internal refresh to write in a black frame between each 60fps source frame. I doubt they've made any changes to the oanel other than to increase refresh rate. If you do speak with them, ask if they plan on supporting BFI with HDMI2.1 once 120fps source can be fed to the TV - this woud require either a further increase to 240Hz internal refresh or addition of a second 'scanout channel' as you state above.

Quote:
Yes, indeed. Also, don't forget that internal diffusions in a scanning backlight will always increase persistence. Scanning backlights often don't achieve MPRT persistence identical to scanning-backlight-segment flash lengths because of light bleed/diffusion. Only strobe backlights do, and fast-GtG rolling-scan OLEDs tend to have persistence (MPRT) matching pixel pulse length.
I don't quite understand this and would appreciate an explanation. Between what is 'best' and what is 'easiest / least costly' (in engineering hours) what is the most practical way for WOLED to implement better BFI / lower persistance in 2019?

Quote:
OLEDs don't quite work that way. On current OLEDs, turning on the pixel is the same thing as refreshing the pixel: You're telling the pixel to turn on to a specific color. OLED pixels currently do not have memory.
You are an absolute genius and a guru when it comes to persistance and moton blur, but as an engineer I am oretty certain you are wrong about that - OLED pixels do have memory (example pixel attached). Since LCD operate in voltage, they only needed one transistor to overwrite the capacitive memory. OLEDs operate in current mode which would destroy the memorized value (analog voltage stored on pixel capacitor) if it was not buffered from the drive current using another transistor. I think this is what you are referring to (amd possibly confusing).

In the attached schematic, raising the 'Power Driver Line' activates current through transistor Q2 to illuminate OLED diode EL1 based on the pixel value that has earlier been stored on CS1 (using Signal Line C and Scan Line A).

So the 'second scannout channel' you have said is needed may already be there - all that is needed to blank a particular row of pixels is to drop the Power Drive Line for that row to ground. Control electronics epukd probably be needed to drive the Power Drive Lines in the required sequence, but the OLED panel itself appears to inherently allow true raster-scanning to be straightforward - a true rolling band of however many lines are desired can be 'lit up' (using Power Drive Lines) to display the current frame while the next frame is refreshed behind them (on blackened lines with Power Drive Line at ground while a ScanLine are activated to write Signal Line voltages onto capacitors C).


Quote:
Yes, high HDR peak brightness is great headroom for low-persistence SDR.
The 10,000nit Sony demo display could reduce persistence by 90% while still having 1,000nits left!

They're already (slowly) beginning to figure it out.

Blur Buster articles are often read by monitor engineers, and the Area51 forum also get many hits from the offices of the manufacturer domain names in my weblogs. Whether my display motion blur photography pursuit camera invention or the free strobe backlight engineering howto, and many others, the free Blur Busters articles already has help fix gaming monitor manufacturers improve their monitors (strobe fixes, frame skipping fixes, etc) -- numerous firmware upgrades have been blamed on me!

Blur Busters writings helped introduce strobe backlights into more monitors. Also, sometimes I test displays for them. I tell them what's wrong with the display (fixable bugs), and they send a new firmware to fix it -- or even a replacement gaming monitor with the new firmware precisely because of my bug report. Such as frameskipping fixes, strobe timing/phase fixes (fewer double-images), etc.

While I have contacts at gaming monitor manufacturers (some of which now outperform plasma in motion clarity for 120fps HFR material), I do not currently have much catchet with television manufacturers, but I'm eventually going to work to change that.
Please let us know what response you get when you speak with LG. It seems as though WOLED is well-suited to deliver CRT-class motion performance if LG thinks about using the macimum HDR-class brightness of the panel and drive it to reduce persistancecas much as pissible (for desired brightness).
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post #30 of 42 Old 01-19-2018, 12:27 PM
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Quote:
Originally Posted by fafrd View Post
Do you know the GtG for LGs WOLEDs? What is the practical lower-persistsnce limit you believe LGs current-generation of WOLED technology can achieve without introducing GtG-related color shift?
Pretty sure the concept of grey to grey time doesn't make any sense on OLED. An LCD has to move the crystals to change the amount of light allowed through. This takes time. An OLED just has to stop generating light or start generating a different amount of light. This is instant. The only thing that should be restricting the speed of an OLED is that you don't have direct connection to every pixel from your controller (since 32 million 10 bit connections from one chip is clearly not feasible) but instead has to go through some interface that lets it address and update each pixel in turn (very quickly). The updates when done would be instant, but the interface needs to get to the pixel first.

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