Question about Strobe and G-Sync

[SS4]

I think things like tearing and stutter might make the experience feel inadequate though. I'll let the expert explain in details though coz i can't really explain it as well as them :p

[Chief Blur Buster]

But there would be less motion blur between the old and new frames, so it would still be far better than a typical 60hz motion blurry monitor, even if the framerate stays the same, right?

Yes, that's right.
However, your eyes are always moving when tracking moving objects on a screen.
Your eyes will be in different positions for the two repeat refreshes, because the refreshes occur at different times.
However, different behaviors occur depending on whether the displays is impulse driven (CRT, plasma, LightBoost, strobe backlight) or flickerfree (regular LCD, sample-and-hold).

Standard LCD Situation
During flickerfree 60fps@120Hz, will look exactly the same as 60fps@60Hz.
Under a high speed camera, two flickerfree repeat refresh half length, is indistinguishable from one longer single refresh.

CRT/Strobed/LightBoost situation
During strobed 60fps@120Hz, will have a double-image effect, much like 30fps@60Hz on a CRT.
You will have less motion blur at stroberate=refreshrate, so clearer motion at 60fps@60Hz strobed than 60fps@120Hz strobed.

To see a clear example of this, view http://www.testufo.com on a 120Hz monitor (in both LightBoost and non-LightBoost mode).

[SS4]

So if improvement is there why stress that 100+ FPS is needed to benefit from lightboost? Or unless its just to benefit fully from it although its beneficial at all framerate which isnt made clear on the website . . .

[Computron]

So are you saying that it would be better (Less motion blur) to have 60fps@120hz with ULMB/LB than it would be to have just 60fps@60hz, but that there would arise another artifact from the double strobe per frame and eye tracking that could outway the benefits?

Is this eye tracking artifact quantifiable worse or significantly annoying enough to warrant turning the ULMB/LB feature off, or is this more of a subjective matter? I dont have a 120hz monitor to experience that example you posted and I don't have a CRT to to see the frame doubling effect either.

When you say you would have less motion blur with the higher framerate, is it simply because there would be less of a difference in the distance covered by moving objects between frames? If that's the case, that is understandable.

I think what we're trying to get at is that it would still be better than 60fps@60hz as with the Standard LCD Situation. (given the eye tracking thing is not a big issue)

[Ahigh]

In general double-imaging is bad. It doesn't matter if you're running your game at 60hz and your display at 120hz or if it's 30hz in software and 60 hz on the display. The effect is visually the same and you see two images on the back of your retina alternating positions every other frame as you eye track and the effect destroys the effect of solid smooth buttery graphics no matter what the framerate is.

It's just an independent artifact. If you have double imaging on a 120hz display when the game can only run at 60hz, you would be better off running the display at 60hz and getting rid of the double imaging for sure.

[shadman]

Imagine someone running through a room with a strobelight being the only source of light. Say they run across, and every strobe pulse they are a little farther each time. Now, imagine the strobe is going twice as fast, and they are still running. With displays sending out a double image, it would be the same as seeing the same guy run across, except for two flashes they are in the same spot, and then suddenly jump to the next spot, stay there for two flashes, etc.

[SS4]

So it would act almost like a sample and hold display even though its flashing unless you get the proper FPS. It would still eliminate thing like ghosting and tearing i believe though.

[Chief Blur Buster]

So it would act almost like a sample and hold display

Yes, repeat strobes is essentially extra "hold" time, while the eyes have already moved onwards. It always happens when framerates is significantly lower than the stroberate. The multiple-image effect even shows up if you're using PWM dimming (e.g. 60fps on a 180Hz-PWM-dimmed display).


(From http://www.blurbusters.com/faq/lcd-motion-artifacts/ )

So repeat strobes essentially creates the sensation of more motion blur -- and sometimes the results are ugly, like this. For example, try turning LightBoost OFF on an older ASUS VG248QE or older BENQ XL2411T (rev 1.0), view http://www.testufo.com/ghosting while turning Brightness down to 0%. You will see a side effect similiar to the above, if you're using an older VG248QE or older XL2411T. That's a side effect of PWM dimming.

even though its flashing unless you get the proper FPS. It would still eliminate thing like ghosting and tearing i believe though.

Strobing does reduce visibility of certain ghost artifacts, but the double-image effect can look like a ghost image itself..

Strobing amplifies visibility of tearing. Improved motion clarity makes tearing/stutters easier to see. The best fix for this is to run stroberate equalling framerate (e.g. 120fps@120Hz) or close to it. Either by a frame cap, VSYNC ON, Adaptive VSYNC. Uncapped VSYNC OFF also looks good too (e.g. 300fps@120Hz).

[SS4]

Good to know, so i guess if/when i get a gsync board for my monitor ill use g sync for games i cant run reliably above 100 FPS (or even lower) and ULMB for those with high framerate for best result then.

[Haste]

I didn't know about the double-imaging effect. That's sounds like something important to consider when setting up the display.

I have a question about this:

Why is EIZO Turbo 240 blinking the backlight at 240Hz showing the same image twice?
Isn't that exactly what you guys just advised against?