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PG279Q ULMB One Ghost Image

Ask about motion blur reduction in gaming monitors. Includes ULMB (Ultra Low Motion Blur), NVIDIA LightBoost, ASUS ELMB, BenQ/Zowie DyAc, Turbo240, ToastyX Strobelight, etc.

PG279Q ULMB One Ghost Image

Postby eumoria » 17 May 2018, 20:23

I'm using a PG279Q and I haven't found a way to capture and image but it's easy to explain: I'm seeing a single a single ghost a little bit behind on the UFO test. The main UFO is very clear and looks as good as my old LightBoost monitor but that single ghost is quite distracting and visible in gaming and other applications.

I've enabled ULMB at 85, 100, and 120 and it all does the same thing. I'm not sure if this is normal for this monitor.

I upgraded from a VG248QE where I used ToastyX's stobe tool to use LightBoost and I had 0 ghosts.

I really hope I'm just overlooking something but I can't seem to figure this one out. G-Sync disabled, no overdrive (although when ULMB is enabled that feature is disabled in the menu so I'm assuming it doesn't matter) everything settings-wise looks ok.

Thanks for any help or anyone else that has this monitor. :?
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Re: PG279Q ULMB One Ghost Image

Postby Chief Blur Buster » 17 May 2018, 20:59

eumoria wrote:I upgraded from a VG248QE where I used ToastyX's stobe tool to use LightBoost and I had 0 ghosts.

There was always a very faint LightBoost ghost but it manifested itself mainly at the top/bottom edges:

Image

(ignore the Large Vertical Total stuff, those tweaks don't work with ULMB-branded version of strobe backlights)

However, ULMB uses better colors, so it's calibrated for slightly more strobe crosstalk. But you also have an IPS panel too, so that brings a little bit more strobe crosstalk.

eumoria wrote:I'm using a PG279Q and I haven't found a way to capture and image but it's easy to explain: I'm seeing a single a single ghost a little bit behind on the UFO test. The main UFO is very clear and looks as good as my old LightBoost monitor but that single ghost is quite distracting and visible in gaming and other applications.

This is called strobe crosstalk, often covered in the Strobe Crosstalk FAQ.

eumoria wrote:I've enabled ULMB at 85, 100, and 120 and it all does the same thing. I'm not sure if this is normal for this monitor.

The PG279Q is an IPS panel, so the pixel response is slower, so there is more strobe crosstalk on an IPS panel -- roughly 3-5% ghost intensity compared to ~0.1%-1% ghost intensity for TN (which is why you never saw the LightBoost strobe crosstalk unless you were really looking closely).

For IPS panels, it's harder to "Cram LCD GtG into the VBI" -- the science of completing pixel transitions between refresh cycles before strobing the backlight.

If you hate strobe crosstalk, try increasing your black levels (brighten blacks) and decreasing your white levels (darken whites). That narrows your dynamic range, reduces contrast ratio, and helps make 90% of the ghosting disappear. You may be able to get ~90-95% of your original contrast ratio, while making the strobe crosstalk much fainter.
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Re: PG279Q ULMB One Ghost Image

Postby eumoria » 17 May 2018, 21:04

Wow man, thank you for the super fast reply. I went through the site's information a bit more and found out what you were explaining.

I think I may also have existing custom config problems but looking at the fullscreen strobe crosstalk test and it falls pretty much in line with the problems with IPS response.

I'll try tomorrow to narrow the dynamic range to eliminate some of it and I'll report back when I have some time to actually tweak it. It's really not all that bad but the previous panel was extremely good but this is apples/oranges I can see.

Thanks again you guys are an amazing resource/community.
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Re: PG279Q ULMB One Ghost Image

Postby Chief Blur Buster » 17 May 2018, 21:36

LightBoost had bad colors because it narrowed dynamic range intentionally to reduce the strobe crosstalk. ULMB has much better colors at defaults.

So it sometimes take an intentional dynamic-range-narrowing (raise black levels, dim white levels) to make some of the strobe crosstalk disappear. This "dynamic-range-technique-trick-to-reduce-strobe-crosstalk" works on many models of ULMB monitors but not as well on some of them.

ULMB and LightBoost uses a special hardcoded strobe-optimized overdrive algorithm that benefit hugely from overshoot room below blacks / above whites -- if you use full dynamic range, there's no overdrive overshoot room for strobe-optimized overdrive tuning.

That's why slightly narrowing dynamic range (brightening blacks & dimming whites) makes strobe crosstalk disappear on several models of ULMB monitors. Your color will still better than LightBoost, even if not as punchy as ULMB defaults.
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