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OLED 4K 30" 60 Hz - Dell UP3017Q

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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Chief Blur Buster » 17 Apr 2017, 08:28

knypol wrote:Why do OLEDS even needs blur reduction feature if their response time is 0.1ms?

See Why Do OLEDS Have Motion Blur?.

There's two different kind milliseconds measurements -- response time (milliseconds) and MPRT/persistence time (milliseconds). The latter measurement is currently the dominating factor. This 0.1ms response OLED still has an MPRT of 16.7ms (1/60sec).

Response time (pixel transition time) isn't the only thing that creates motion blur, it's the motion blur caused by sample-and-hold (also called "Persistence" or "MPRT"). Even 0.1ms response OLEDs have 16.7ms of persistence (for a 60Hz non-strobed OLED).

Response is the pixel transition time, and persistence is the pixel static time (a full refresh cycle for a sample-and-hold display). As you track moving object on a screen, the static image of a refresh cycle (a 60Hz refresh is displayed for 1/60sec) is blurred across your moving eyes. Your eye position at the beginning of the 1/60sec is different than your eye position at the end of the 1/60sec, but the refresh cycle is being displayed for a full 1/60sec.

That's why Oculus and Vive uses 90Hz strobing (rolling scan) on their OLEDs for their VR headsets.

For an animation example of motion blur NOT caused by display response time -- see TestUFO Eye Tracking Motion Blur.


(Click and maximize to go full screen)

1. Observe how the stationary UFO doesn't blur the vertical lines.
2. And observe how the moving UFO forces your eye movements to horizontally blur the vertical lines to fill the gaps.

This illusion (created by motion blur) still occurs on OLED displays unless they're strobed as well. It's motion blur caused by eye tracking -- and a motion blur that can't be fixed by instant response (even 0.0ms won't fix this type of blur).

The only way to reduce this kind of motion blur is to shorten the refresh cycles -- either by raising refresh rate -- or by adding bigger-and-bigger black periods between the visible static frames (refresh cycles). Both will shorten the time of displaying a static image, giving it less opportunity to be motion-blurred across your vision.

So, in other words, to get 1/1000sec persistence (1ms), you need to make each frame visible for 1ms -- which means 1ms flashes of each frame. You can do that far more easily with a strobe backlight, than doing 1000fps@1000Hz (to avoid strobing). So in other words, we are stuck with strobe-based technologies for a very long time. Another technique is frame-interpolation (fake frames), but that can add lag or image artifacts. Oculus Rift also has an interpolation mode to convert 45fps to 90fps via reprojection tricks. Also, many HDTVs have modes that convert 60fps to 120fps or 240fps via interpolation. These all shorten frame visibility time, and reduce motion blur.

Many articles have been written about this, including Michael Abrash (Oculus) -- Down the VR rabbit hole: Fixing judder for further reading about this too. MPRT is the nomenclature found in scholarly papers [Google Scholar], but some have use the word "persistence".
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby RealNC » 17 Apr 2017, 13:53

knypol wrote:Why do OLEDS even needs blur reduction feature if their response time is 0.1ms?

Because response time has almost nothing (or very little) to do with motion blur :-)

Image retention is the major cause for motion blur. 0.1 ms response time isn't going to help with motion blur if the image is retained for 16.7ms on the screen at 60Hz. Now if the image was only shown for 0.1ms, and then there were 16.6ms of black nothingness until the next frame, then this would completely eliminate motion blur.

But I don't think that monitor does that. I'm confused like everyone else here what Dell means with "flicker"... It's an OLED, so there's no backlight. So, what exactly is flickering here? I highly doubt this monitor is strobing the pixels. Or is it? If yes, then Dell's words probably mean they do 120Hz strobing. But again, it doesn't sound like this is a strobing OLED.
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Falkentyne » 17 Apr 2017, 15:30

Slow response times cause things like streaking, color deformations on moving objects (past the primary frame of the object) or RTA/overdrive artifacts. Slow response times can also cause extremely high crosstalk on a monitor with a traditional top to bottom based strobe method (blur reduction).

If an OLED had a strobe based blur reduction (with the OLED's turning off and on once each frame), there would be absolutely ZERO CROSSTALK on the screen and ZERO overdrive artifacts (since overdrive is only used on LCD panels to compensate for their slow response times on white to black to white color cycles).
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Chief Blur Buster » 17 Apr 2017, 15:45

Falkentyne wrote:Slow response times cause things like streaking, color deformations on moving objects (past the primary frame of the object) or RTA/overdrive artifacts. Slow response times can also cause extremely high crosstalk on a monitor with a traditional top to bottom based strobe method (blur reduction).

HISTORICAL INFORMATION: Back in the Bad Old Days of LCDs -- slow 33ms LCD days -- response time definitely WAS a major cause of motion blur. Slow response times used to add lots to motion blur when response time was this slow. The slow pixel response time prolonged tracking-based motion blur far beyond the length of a refresh cycle.

But nowadays, with response time a tiny fraction (1ms) of a refresh cycle (16.7ms at 60Hz), the persistence/MPRT (sample-and-hold) is the dominating cause of motion blur now.

Nowadays, with fast response -- a modern 1ms or 2ms LCD panel is spending more of it time displaying pixels statically than transitioning pixels. But static images smears across your vision during eye tracking -- as seen at http://www.testufo.com/eyetracking animation.

That said, it's definitely true that strobed displays kind of make ultra-fast response important because of the strobe crosstalk issue.
You are effectively trying to squeeze as much as LCD GtG response time as possible into the tiny period between refresh cycles (the more complete the GtG transitions occur in total darkness, the less strobe crosstalk double-image artifact). You definitely can have MPRT measurements smaller than LCD GtG measurements (in milliseconds) -- Breaking the LCD response limitation barrier -- this is what LightBoost and ULMB manage to successfully do nowadays (high speed video of the first good gaming monitor strobe backlight, LightBoost). LCD response is occuring practically hidden in the dark periods between refresh cycles (LCD scanouts being done in dark) -- and persistence is the bright period (flashed on virtually fully-refreshed frames). The near-zero-strobe-crosstalk panels are almost always TN-panels, usually with NVIDIA LightBoost/NVIDIA ULMB/Samsung. More information in Motion Blur Reduction FAQ.

OLEDs are strobed very differently from LCDs, they instead use a rolling scan -- they are scanned with an "ON" scan, with a "OFF" scan following closely behind. High speed video of an OLED rolling scan (older Sony TriMaster OLED display).

Five years ago before Blur Busters was created -- few people were aware that this was even possible (slower LCD GtG panels in strobe mode having far less motion blur than faster-responding technologies like OLED when they're not strobed).

I had already long known this that tracking-based motion blur was the dominating factor at today's response speeds.

Even today, people are surprised their Samsung Galaxy OLED 0.1ms phone has far more motion blur (during fast scrolling) than a ULMB/LightBoost LCD 1-2ms display. Blur Busters was created less than 5 years ago to help educate people of the various causes of display motion blur including other than pixel response.
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Chief Blur Buster » 17 Apr 2017, 17:36

Vega wrote:Ya Falk I am quite confused. The frame rate is 60 Hz. PWM basically has nothing to do with frame-rate. It states it "eliminates" flicker by doubling the screen frame rate. So uh, it flickers at 120 Hz? I doubt Dell was stupid enough to set the PWM flicker that low. The PWM setting on Samsung laptop OLED panels is 240 Hz. I think maybe the Dell will do it at 480 Hz when set to "flicker free'?

What I would consider "eliminates flicker" would be no PWM at all. But what I think they mean is the frequency is high enough you can't actually "see" the flicker. I guess tomorrow I will know by adjusting the shutter speed on my camera.

You can find out when you view http://www.testufo.com/ghosting
-- Two UFOs -- means double strobe
-- One UFOs with 50% less blur than unenhanced 60Hz -- means either interpolation or single-strobe at 50%:50% ON:OFF duty cycle.

It can mean multiple things
(1) It interpolates.
(2) It single strobes (120 strobes/sec at 120fps@120Hz) or (60 strobes/sec at 60fps@60Hz)
(3) It double strobes (120 strobes/sec at 60fps@60Hz)
(4) It does a combination of (1) and either (2) or (3). A display can interpolate 60fps->120fps and then single-strobe each frame 50%:50% ON:OFF to simulate 240Hz clarity. Probably not.

I'm guessing either (1) or (2) or (3)

From a strobe-backlight perspective, or pulsed/scanned OLED perspective, 120Hz strobing effectively eliminates 60Hz flicker. It still flickers, just much less so. So some manufacturers sometimes market things this way. Flicker-free blur reduction is either interpolation or high-frequency strobe mode -- proper strobing is effectively simply 1-flash-per-refresh PWM. Therefore proper blur-reducing 240Hz "PWM" would require 240fps@240Hz to successfully work in blur elimination (without double or multi-image PWM artifacts). And proper blur-reducing 480Hz "PWM" would require 480fps@480Hz to successfully work in blur elimination (without double or multi-image PWM artifacts). And so on.

So to find out what the hell the display is doing, you will need to run a TestUFO motion test -- the artifacts instantly tells us exactly what the display is doing (if any) to reduce motion blur -- or whatever it's (sometimes legitimate, sometimes not) doing to simulate "120Hz" out of 60Hz.
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Vega » 17 Apr 2017, 20:15

Holy hell this thing is beautiful.... 5.4ms MPRT at 60 Hz! Gotta love near instant OLED pixels strobing at 120 Hz.
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Vega » 17 Apr 2017, 21:05

Oh crap the motion clarity at 60 Hz single strobe is crazy. 4.4 ms MPRT, for 60 Hz! The flicker is too much for me though, I'll stick to double strobe 120 Hz.
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Falkentyne » 17 Apr 2017, 22:25

Vega? What?
This thing has built in blur reduction???
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Glide » 17 Apr 2017, 22:37

60Hz OLED with 4.4ms persistence? That sounds fantastic.
Surprised to hear that it's worse than 60Hz CRT flicker though.
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Re: OLED 4K 30" 60 Hz - Dell UP3017Q

Postby Chief Blur Buster » 18 Apr 2017, 12:23

Fantastic! 4.4ms MPRT single-strobe rolling-scan 60Hz would make this a kickass display for 60fps gaming.

MAME arcade cabinet builders, here's your dream CRT replacement with "CRT phosphor simulator" HLSL shader (at 4K!) + CRT-perfect blacks + CRT style rolling scan + CRT like motion sharpness! (1/4th motion blur of 60Hz LCD). If you can afford it...

But, can this do true 120Hz at all, even at a lower resolution, e.g. 720p or 1080p?

It's a shame to have a wonderful 4.4ms MPRT without more Hertz -- 120Hz would be fantastic.

(Remember everyone, 4.4ms MPRT is far better than "1ms GtG" (for non-strobed LCDs)
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