BenQ XL2411Z Bad Ghosting in one part of the screen + Stuter

[OptiBot]

Today I noticed that my BenQ XL2411Z has terrible ghosting issues in the lower middle part of my screen when using blur reduction. I also noticed that my monitor has some stuttering issues when moving different windows around, in game (Any game), and when I was running the UFO test (only with blur reduction on). These two problems don't happen when I turn blur reduction off.

Here is a picture of the full screen:
http://i.imgur.com/TiNVDFR.jpg

Here is a comparison between the not so bad ghosting and the terrible ghosting:
http://i.imgur.com/Sw4crKB.jpg

Whenever I move the browser around it always stays with that one spot on the monitor.

Is there a fix for this or is my panel just defective?

[lexlazootin]

So the panel switches images from top to bottom and ULMB trys to turn the back light on and off when the switching is complete, but because the switching isn't fast enough, you get a little bit of the last img at the bottom of the screen.

You can try to configure the ULMB with http://www.blurbusters.com/benq/strobe-utility/ and try to "overclock" using the settings found here: http://forums.blurbusters.com/viewtopic.php?f=13&t=560 but nothing will make it perfect.

The stutter is just regular studder but ULMB just makes it more apparent, more fps can kinda fix it.

[Q83Ia7ta]

You can try to configure the ULMB with http://www.blurbusters.com/benq/strobe-utility/

It's for BBR (BenQ Blur Reduction) not for ULMB :X

[Falkentyne]

So the panel switches images from top to bottom and ULMB trys to turn the back light on and off when the switching is complete, but because the switching isn't fast enough, you get a little bit of the last img at the bottom of the screen.

You can try to configure the ULMB with http://www.blurbusters.com/benq/strobe-utility/ and try to "overclock" using the settings found here: http://forums.blurbusters.com/viewtopic.php?f=13&t=560 but nothing will make it perfect.

The stutter is just regular studder but ULMB just makes it more apparent, more fps can kinda fix it.

Actually that's not it.
You get the 'next' frame (actually depending on your Strobe Phase, it could be the CURRENT frame at the bottom and the NEXT Frame over 80% of the main part of the screen) at the bottom, not due to the backlight switching being too slow, but being too -fast-.

Its the pixel transition of LCD panels that are too slow.
A pixel can transition from a full color cycle (a full cycle is black to white to black) depending on the actual color it starts at end the color it ends at from anywhere from 2 milliseconds to 20 milliseconds. That's how long it takes a pixel to completely update under BEST to WORST conditions.

However a backlight strobe (backlight shutting off, and being on for a short period of time and off) occurs once per FRAME. The frame time is equal to the refresh rate time, which for 120hz for example, is 8.3 milliseconds and for 100hz is 10 milliseconds. For 144hz, 6.9milliseconds and 60hz, 16.7 miliseconds.

Set your monitor to 60hz refresh rate, turn on Blur reduction, set the Strobe phase to 100 (lowest input lag) or 000 (1 frame HIGHER input lag but lowest crosstalk ("bad ghosting") at the bottom of the screen. Then enable blur reduction with this test running FULL SCREEN (F11) + full screen selected in browser.

http://www.testufo.com/#test=photo&phot ... &height=-1

Notice that the "bad ghosting" (crosstalk) only covers a VERY small section of the screen? Remember what I told you about "5-20ms right?'
60hz refresh rate is 16.7 milliseconds and panels REFRESH FROM TOP TO BOTTOM. So naturally there's MORE time between each frame at 60hz, for MOST of the refreshes to finish. What's left is what is at the bottom. A little crosstalk.

Now, (to avoid issues with VT Tweaks and backlight shutting off with strobe phase 100), set it to 144hz refresh rate directly.
Use strobe phase 100 (lowest input lag) or strobe phase 000 (1 frame HIGHER input lag but less crosstalk).

Notice the difference?

Now there's a *LOT* of that bad ghosting. MORE than double that what you saw at 60hz. (fun fact: WITHOUT a Vertical Total tweak, the crosstalk amount at 120hz is EXACTLY DOUBLE that of 60hz. That's pretty logical and self explanatory).

Why is there so much crosstalk?
Because. REFRESH RATE DOES NOT MAKE THE PIXEL TRANSITIONS FASTER! It just makes the frame time and input lag lower.
You have a 6.9 millisecond frame time at 144hz.
But you STILL have from 2-20ms pixel TRANSITION TIME Required.
So the crosstalk will cover MORE than half the screen.

Now you might ask "why don't I get crosstalk if blur reduction is OFF"?
Because if blur reduction is OFF, you don't see pixels caught in transition because the entire frame is visible all the time. Blur reduction only shows the frame for a SHORT TIME, to remove motion blur, so because the next "strobe" occurs so fast, the pixels won't be transitioned yet, and you get parts of two frames on top of each other (the current frame and the next frame).

With blur reduction off, since the entire frame is always visible, you only see the frame itself. However instead of crosstalk, you see ghosting of the entire frame and you get 'inverse' coronas if the overdrive is too high and copies of the main frame if overdrive is disabled. There's more hocus pocus going on here than it seems, however. For example with blur reduction disabled, you will get "streaking" and maybe spectral white ghosting of black objects, while you won't get that with blur reduction enabled