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LCD with 0.5ms response time! -- Chief Blur Busters' Opinion

Posted: 24 Aug 2017, 20:50
by Chief Blur Buster
As Chief Blur Buster, I am fascinated to hear of 0.5ms response time. And I think this is important to break the 1ms barrier (for sometimes unexpected reasons)...

AOC to Release 27″ AG273QCX FreeSync 2 Monitor with 0.5ms Response Time in 2018

Image

0.5ms response time actually becomes important for strobe backlights. Whether it's GtG (pixel transitions) or MPRT (persistence / motion blur), 0.5ms is still quite impressive.

MPRT
MPRT = Moving Picture Response Time = frame visibility time = persistence = motion blur = "1ms equals 1pixel of motion blur at 1000 pixels/sec motion" (The Blur Busters Law)

GtG
GtG = Grey to Grey = pixel transitions = time taken to change from one color to the next.

It's possible for MPRT < GtG and MPRT > GtG. And I have a high speed video of LightBoost, which shows MPRT breaking the GtG barrier. This is possible because GtG is kept in the dark during the black (OFF) period of the strobe backlight.

Sample-and-hold display: MPRT is the refresh cycle length
Strobed display: MPRT is the strobe length

For a sample-and-hold display (non-strobed), GtG almost doesn't matter anymore once it is well below a refresh cycle length. GtG practically ceases to improve motion blur on non-strobed displays once GtG is far below a refresh cycle length. We now have 60Hz monitors (16.7ms refresh cycles) with 1ms GtG. There is no motion blur difference between 1ms GtG and 2ms GtG for a non-strobe display.

HOWEVER.... once you throw either {1} strobing (e.g. ULMB) or {2} ultrahigh refresh rates (e.g. 480Hz) into the mix, suddenly, GtG becomes WAY critically important again.

Currently, I have no idea if the AOC displays use 0.5ms GtG or uses 0.5ms MPRT. But either number is very impressive.
If it's 0.5ms GtG, that's the first time I've seen an LCD go that fast (even for the typical GtG10%->GtG90% measurement)
If it's 0.5ms MPRT, that automatically means a strobe backlight.

Hopefully it is extremely good brightness. The shorter the strobe flash length, the brighter the backlight needs to be in order to compensate for the short strobe flash length. If it can achieve more than 200 nits while maintaining 0.5ms MPRT, that may actually be a first outside of a laboratory.

It's indeed possible to keep 5ms GtG VA response while having 0.5ms MPRT responses. You simply flash a strobe backlight for 0.5 milliseconds, once a refresh cycle.

(1) Pixel transition speed is still very important with strobe backlights (ULMB, LightBoost, DyAc, ELMB, etc.) because of strobe crosstalk. See Strobe Crosstalk Explanations. The faster the GtG, the less strobe crosstalk, because more of the GtG limitations has been hidden in the dark periods between strobe flashes.

(2) Pixel transition speed is still very ultra-high-refresh-rates. You need pixel transitions to still be a fraction of a refresh cycle. For future 480 Hz LCD monitors, GtG of 0.5ms will be extremely beneficial for that. We are the first website in the world to publish 480 Hz tests and motion clarity about started to resemble "strobeless LightBoost" or a "completely flickerless CRT". This is tantalizing glimpse of a possible future; using brute force Hertz to have blurless sample-and-hold displays! Getting 2ms MPRT persistence without black periods (zero strobing) requires ~500fps@500Hz to have frame visibility times of 2ms with absolutely no flicker/strobe/impulsing/etc needed. Getting 1ms persistence equalling a 1ms strobe length, would require a strobeless 1000fps@1000Hz display to achieve the same motion clarity via sample-and-hold.

Regardless whether 0.5ms is an MPRT or GtG measurement, even if only 80% accurate (GtG10->90%), it is still an impressive number.

Bring on the "0.5ms displays" of year 2018.

Re: LCD with 0.5ms response time! -- Chief Blur Busters' Opi

Posted: 24 Aug 2017, 22:06
by RealNC
Unfortunately, this has been drowned and killed by AOC's marketing bullshit. Just look at their image.

Re: LCD with 0.5ms response time! -- Chief Blur Busters' Opi

Posted: 24 Aug 2017, 22:32
by Chief Blur Buster
Marketing aside, it's a new AU Optronics panel and should be fascinating to see the result of.

Hopefully it's not a wimpy 10 nits strobe backlight mode, just to boast 0.5ms MPRT -- but if they are making it a prominent advertising feature, it must be outputting sufficient enough candles to make 0.5ms actually useful (well north of 100 nits).

Still very interested!

Re: LCD with 0.5ms response time! -- Chief Blur Busters' Opi

Posted: 24 Aug 2017, 23:09
by lexlazootin
Yea, you don't have to trust in AOC, just AUO. Although i'm not sure if it's even worth believing since response time is a marketing gimmick anyways. No monitor hits a average of 1ms and you would need to use such absurd OD it wouldn't be worth it.

A true response time number to be shown would be nice but so many gamers will only buy 1ms response time marketing that it would only hurt them.