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

[k2viper]

Very strange, u're sure that you changed 1920x1080 240hz resolution?
It's under extension blocks (CRU). Because If I change 239,759 to 239,760 it results in actual 239,760 refreshrate. Or u're using custom 240hz timings (large VT etc)? It also may be GPU related since i have Nvidia and you have AMD.
My exact default 240hz is on the pic.

Anyway, as I found you need to do exact 239,760hz to get off judders.

[dogroll]

Very strange, u're sure that you changed 1920x1080 240hz resolution?
It's under extension blocks (CRU). Because If I change 239,759 to 239,760 it results in actual 239,760 refreshrate. Or u're using custom 240hz timings (large VT etc)? It also may be GPU related since i have Nvidia and you have AMD.
My exact default 240hz is on the pic.

Anyway, as I found you need to do exact 239,760hz to get off judders.

It's impossible for me to get 239.760Hz exact via CRU. Only 239.759 or 249.764. If I change the horizontal rate or pixel to try to compensate, it also jumps between 239.759 and 239.764.

[Chief Blur Buster]

It's a very complex mathematic interaction between all the numbers. So people have to post screenshots of their entire ToastyX settings, because the refresh rate granularity changes everytime even when just one value changes.

For example, if I change certain random Horizontal or Vertical numbers, I can see the granularity of Refresh Rate change.

So you must copy all ToastyX numbers exactly to get somebody else's exact refresh rate. Even Horizontal Total matters a huge deal. If one number is off, then it's possible you may not be able to match somebody else's exact refresh rate, so every single number in the screenshot must be copied 1:1 exactly, to get the exact granularities achieved.

It's a quirky math-rounding behaviour.

[k2viper]

Just started softMCCS. Such a powerful tool! I'm impressed.

LG 27GK750F-B uses Mstar scaler named "0x00FF00". My display's firmware ver is 3.6.

Do I need to run a conformance test? May it help me to find meanings of all those "Manufacturer specific" VCP's? If my LG will support strobe controls, they are somewhere under these VCP's, am I right?



Quick findings (not to lose):
LG 27GK750F-B DDC/CI manufacturer specific commands:

0xF9 = Black stabilizer
0xE4 = ??
0xE5 = ??
0xE6 = ??
0xE7 = ??
0xE8 = gamma preset
0xE9 = ??
0xEA = ??
0xEB = ??
0xEF = ??
0xF4 = ??
0xF5 = scaling mode
0xF6 = ??
0xF7 = overdrive mode
0xF8 = freesync toggle
0xFD = ??
0xFE = ??
0xFF = ??

Strange that none of these ?? values showed yourself as toggle strobing. But strobing is definitely DDC/CI controllable because LGs own app OnScreenControl.exe can toggle strobing.
I also tried to toggle strobing via OSD and then refresh the VCP table (F5) and none of the "manufacturer specific" values changes.

My general goal is to discover, does LG have strobe timings controls like Benqs, or not. I kinda not expected that none of these specific VCP's work even as toggling strobe...

[lexebidar]

I see some talk about this monitor recently... It is pretty pricey as for nongsync monitor and for being 1080p at 27".
Any particular reason for it? I've seen 1 or 2 people saying it's the BEST non gsync monitor... which I am inclined to be doubtful by nature
As in other topic I've created... I just happen to have 500$ back from returning second 240hz aoc ag251fg for its bad blb and picture quality.. and since I am burned on gsync and aoc, lg is kinda tempting. Although I am also burned on 240hz

[Chief Blur Buster]

Strange that none of these ?? values showed yourself as toggle strobing. But strobing is definitely DDC/CI controllable because LGs own app OnScreenControl.exe can toggle strobing

<Advanced Strobe Hacking>

It may not be a binary toggle (0/1) but a magic value (0x00 through 0xFF) or a PWM duty setting (0x00 through 0xFF) or some other math formula of on-ratio versus off-ratio, or the raster (interrupt) scanline to begin turning on the backlight, versus the scanline to begin turning off the backlight (e.g. raster-driven strobe triggers).

There are many legitimate firmware workflows to operate a strobe backlight. Basically, a strobe backlight is simply a 1-flash-per-refresh-cycle PWM that is optimized for motion blur reduction.
-- Strobe length/phase workflow
-- Raster timing workflow (Scanline number for ON, scanline number for OFF)
-- Microsecond timer timing workflow (microseconds from begin of VSYNC for ON, microseconds from end of VSYNC for OFF)
-- PWM timer controllers
-- Etc.
Some workflows means one would need to change two or three or four bytes simultaneously to their correct values, before strobing enables itself.

For the raster timing workflow, basically a pair of two registers may be a simultaneous hybrid of strobe on/off, strobe duty, and strobe phase (e.g. raster-driven strobing -- a register for ON, and a register for OFF). It could be 4 DDC bytes -- if you're using a pair of 16-bit raster registers for raster-timed strobe backlights.

Due to the GtG delay (high speed video) strobe phase is slightly offset to compensate for LCD GtG. So many strobe backlights begin turning on very late into VBI, and begin turning off sometime after the next refresh cycle has already begun. That centers the strobing in the middle of lagged GtG (between refresh cycles), rather than middle of electronc-signal VBI. So raster-driven strobe backlight workflow may be used as a means of calibrating the timing of ON, and the timing of OFF.

What you want to do is.
1. Turn OFF strobing in menus.
2. Dump SoftMCCS (All VCP registers)
3. Turn ON strobing in the menus
4. Dump SoftMCCS (All VCP registers)
5. Diff the two files.
6. Use the changed register to reverse-engineer the strobe enable/disable.

But it could be something else completely in the firmware, such as something similar to NVIDIA's DRM-based enabling of LightBoost -- requiring a continuous encrypted handshake before it's enabled. But I doubt this is the case, because LG's strobing works with any graphics card, so I think it's something else formulaic other than a simple ON/OFF.

</Advanced Strobe Hacking>

[Chief Blur Buster]

I see some talk about this monitor recently... It is pretty pricey as for nongsync monitor and for being 1080p at 27".
Any particular reason for it? I've seen 1 or 2 people saying it's the BEST non gsync monitor...

From the photos I've seen, I can confirm it /seems/ to have one of the best 240 Hz strobing of any 240 Hz strobe display -- I'm good at interpreting strobe crosstalk.

That said, I'd have to see the monitor in person for its other attributes... It might still have a muddy black field, for example.

[k2viper]

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

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 Russla 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).

[k2viper]

What you want to do is.
1. Turn OFF strobing in menus.
2. Dump SoftMCCS (All VCP registers)
3. Turn ON strobing in the menus
4. Dump SoftMCCS (All VCP registers)
5. Diff the two files.
6. Use the changed register to reverse-engineer the strobe enable/disable.

But it could be something else completely in the firmware, such as something similar to NVIDIA's DRM-based enabling of LightBoost -- requiring a continuous encrypted handshake before it's enabled. But I doubt this is the case, because LG's strobing works with any graphics card, so I think it's something else formulaic other than a simple ON/OFF.

</Advanced Strobe Hacking>

Thanks! Very detailed and interesting! I also thought that I need to look in detail, what values changes when I toggle strobing in OSD.
If I even had enough time...

[lexebidar]

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

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 Russla 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