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LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Chief Blur Buster » 16 Mar 2018, 14:25

k2viper wrote:Btw Chief, there's new pics of XL2546 crosstalk viewtopic.php?p=31696#p31696
And I must say its "Area" and probably "Intensity" look pretty much the same as LG's. Yes, XL2546 has much more visible overshoot, but looks like strobe timings are very similar between the two.
LG also using an Mstar scaler. So there's still a hope that some DDC/CI commands may control strobe like XL2546.

Was the photographs taken at default Vertical Total or during Large Vertical Total?

See my reply: viewtopic.php?f=4&t=3937&start=10#p31708

Chief Blur Buster wrote:
k2viper wrote:Got some XL2546 crosstalk pics from a russian forum user, they can be seen here: https://drive.google.com/file/d/1TzZTD5 ... v7mQR/view

I'd say its pretty similar to LG's crosstalk, but XL2546 definitely have much more obvious overshoot which overall makes picture look worse then LG's.

Large Vertical Totals will help hide the crosstalk zone offscreen on most of the 144Hz BenQ/ZOWIE monitors. The longer VBI gives more time for LCD GtG to complete between refresh cycles.

The end result is that you'll have more space to move the "crosstalk bar" (via "Strobe Phase" adjustments) off the screen before it wraps-around to the opposite edge of the screen -- imagine a Large Vertical total as virtual screenspace below bottom edge of screen or above top edge of screen, that provides "crosstalk bar hiding room".

Image

That's a scanout diagram of a Large Vertical Total via Custom Resolution Utilities.

This specific example is 100 refresh cycles per second, even though a display panel is scanned out in 1/144sec.

The bigger VBI -- the easier to hide LCD GtG in the VBI (aka VSYNC interval). The bigger the VT, the better. And it's easier to have larger VT at lower refresh rates. That's why lower-Hz strobing has less strobe crosstalk -- LCD GtG is hidden between refresh cycles = more strobe crosstalk disappears.

The VBI size is (Vertical Total - Vertical Active) -- so VT1350 on 1080p means you've got 1080 visible rows of pixels and 320 VBI rows of pixels as the pause between refresh cycles.

The VBI can even be bigger than the image. e.g. 60Hz with the scanout velocity of 240Hz -- approximately ~VT4400 works on certain 240Hz monitors. You open Custom Resolution Utility, go to highest Hertz, put radio button on "Pixel Clock" (lock the pixel clock) and then increase the Vertical Total to lower the refresh rate to your target refresh rate -- and voila. That's the Appendix A approach of http://www.blurbusters.com/crosstalk for creating brand new Large Vertical Total modes for an existing monitor. A quadruple VT (1/240sec) on 60Hz will create a 12 millisecond VBI pause between the 4.2ms scanouts, big enough to drive a truck through, even for 5ms IPS and VA GtG.

There is no limit how big a VBI can be -- except the monitor's technological limitations on tolerating such a large VBI.

(FreeSync/VRR is simply a variable Vertical Total -- variable pause between refresh cycles).

For LG's case, the large-VT 240Hz mode is simply a 240Hz with the scanout velocity of 280Hz. :)
Which is why I am impressed at LG -- its unique ability to do Large Vertical Total at 240Hz!! It's only approximately 0.8ms VBI, so won't hide 1ms GtG (realworld >1ms GtG).

The HDMI 2 lag-reducing Quick Frame Transport is essentially a form of Large Vertical Total -- but you can do QFT tricks on any signal like DVI, DP, etc.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby A Solid lad » 16 Mar 2018, 15:58

Just ordered the LG, spotted it going for sale today... 430 eur.
I've read so many things about you trying to improve crosstalk... and I don't want to again, unless it's necessary, so my quick question would be:
In the end, did the default settings work out best for 240hz strobing, or should I re-read this thread to find timings, with which I can improve it?
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Monitors I've owned/tried: Benq XL2411Z, Alienware AW2518Hf, Acer XF270HA, LG 27GK750F-B
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Chief Blur Buster » 16 Mar 2018, 16:27

This is the working VT1302 for the LG, creating the best known 240Hz strobed result (up to this point)

Image

I don't have any 120Hz VT yet at this time, but it would be fun to try the Pixel Clock (putting radio button on Pixel Clock) and keep increasing VT until the refresh rate reaches "120". That would create a VBI larger than the refresh cycle itself, given this appears to be a 280Hz scanout velocity.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Spyro » 16 Mar 2018, 16:31

k2viper wrote:I'm not sure that "better" is the exact case, but if you're looking for 240hz strobing, this LG is definitely better. But if you need gsync (and dont mind strobing), XB272 is fine. I suppose they both are on the same AUO panel (XB272 is "frameless" version of this panel, LG is "normal")
In my country XB272 also costs about 200USD more then LG.
That's up to you to decide. In terms of quality, LG is good in everything it features. But it doesnt have Gsync. On the other side, XB272 has Gsync but do not have 240hz strobing, and also more expensive because of Gsync price premium.

XB272 was released earlier, but I skipped it because I was looking for 27" 240hz with full 240hz strobing.

What's better for fast-paced FPS gaming (like Quake) G-SYNC or Strobing?
The XB272's ULMB is not strobing?
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Chief Blur Buster » 16 Mar 2018, 19:07

Depends.
-- Most of the time, for fixed-crosshairs-based games with framerates above refreshrates, competitive players tend to prefer VSYNC OFF.
-- However, if framerates are below refresh rates, sometimes GSYNC improves things if the game is very stuttery (e.g. GSYNC can improve PUBG gameplay)
-- Yet others appreciate strobing if you're tracking eyes all over the screen. Gaming tactics in FPS involves lots of eye tracking (e.g. moving objects hidden in cluttered scrolling backgrounds -- like high-speed low-altitude helicoptor flybys while shooting tiny enemies below, ala Battlefield 3, etc).
-- ULMB is strobing-based. See Motion Blur Reduction that explains what strobing is.
-- See HOWTO: Using ULMB Beautifully or Competitively
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 17 Mar 2018, 06:52

Spyro, Chief says right - sometimes strobing is better in fast-paced games, sometimes not.

E.g. CSGO-like games have many fixed-gaze scenarios when player controls some area and there's not much movement and target tracking.
On the other side, games like Overwatch or QC (not duels) have many intended target tracking. I beleive strobing really helps to track targets, because its making target edges sharper and then more natural.
240hz strobing though, have much less perceptible downsides then 120/144hz due to higher stroberate: inputlag price for strobing typically is about 1/2 of the refresh cycle time (only about 2ms at 240hz), and flickering is much less visible due to higher stroberate.

A Solid lad, I ended up using VT1304 at 240hz, this mode makes exact 239,76hz on my system, its stable and I dont get a behavior dogroll mentioned earlier (juddering/stuttering after MBR toggling). Tweaking is easy, run CRU, go to extension block, find 1920x1080 with 239.759 and change only Vertical total to 1304. Save, reboot.
Also I recommend using 1:1 scaling mode, it's stated that no adjustments are made to the input signal in 1:1, so I think its the real "instant" or "direct" mode with lowest input lag.

Thats my timings

Image
Last edited by k2viper on 17 Mar 2018, 07:05, edited 1 time in total.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 17 Mar 2018, 07:02

Chief Blur Buster wrote:Was the photographs taken at default Vertical Total or during Large Vertical Total?

See my reply: viewtopic.php?f=4&t=3937&start=10#p31708


XL2546 photos were at default VT's.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Spyro » 17 Mar 2018, 13:08

Why is the LG 27GK750F-B 2ms Response Time if it has the same panel has the Acer Predator XB272 that is 1ms Response Time?
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 17 Mar 2018, 13:28

That's only marketing numbers, dont take it seriously. They are equal in response times.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby dogroll » 17 Mar 2018, 17:13

lexebidar wrote:
k2viper wrote:Its blacks (backlight bleed) is pretty OK, nothing to complain about. Colors, overdrive, other general features are fine out of the box.

lexebidar wrote:I see some talk about this monitor recently... It is pretty pricey as for nongsync monitor and for being 1080p at 27".


Pricey, are you sure? Recommened price on LG's site is 449 USD currently. I got it in the late January in Russia for ~480 USD. Not that much for 27" 240hz imo. There is none 27" 240hz cheaper, excluding two Acer models: XF270HA and KG271B
But XF270HA has confirmed and not yet fixed frameskipping (critical problem), and KG271B looks pretty similar (but no user reviews on that yet). And both Acers dont have strobing (blur reduction).
So yes, quality-wise, feature-wise, LG is kinda one of best 27" 240hz if you dont mind gsync (I dont, even having Nvidia gpu).

So You are a good person to ask:
1)Please post a pic of black image full screen. I want to see edge bezel bleeding
2)How is gamma and contrast? Are there gamma settings on LG?
3)Is 1080p at 27" bothersome?
4)Is the quality of picture worse than 144hz monitors (of eiter 24 and 27")?
All those questions are aside of dyac strobing since we know this is one of the best currently. But I am not willing to get 240hz with worse quality over potentially better quality 144hz monitor. 144hz to 240hz is not much difference. I've tested myself on (now returned) aoc ag251fg.
thx :D


For me the image quality is better than my old 144Hz monitor (ViewSonic XG2401 with AUO M240HW01 V80). The 27GK750F with AUO M270HTN01.x panel has less grainy matte coating. The gamma (in mode 4) is also superior, requiring less adjustment hardware calibration.
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