Need 1000fps@1000Hz for 1ms persistence without strobing

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RealNC
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by RealNC » 15 Jan 2014, 18:23

Guys, I don't mean 30Hz. I mean 30FPS. Playing at 30FPS with a 120Hz mode and with VSync enabled was always sharp. Why can't the same thing happen with, say, Light Boost? What's the difference?

Or I am understanding this wrongly? *Is* there actually any blur when playing a 30FPS game on a 120Hz monitor with Light Boost enabled? I know there is NO blur on a 120Hz CRT, so why would there be on a 120Hz Light Boost LCD?
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by Chief Blur Buster » 15 Jan 2014, 18:26

RealNC wrote:Guys, I don't mean 30Hz. I mean 30FPS. Playing at 30FPS with a 120Hz mode and with VSync enabled was always sharp. Why can't the same thing happen with, say, Light Boost? What's the difference?
It would be pretty smooth, but you would get a quadruple-ghost effect. This is not pleasant looking to my eyes, but might be acceptable to some people. It's a matter of personal preference if they prefer a strobed dispay running at frame rates far below strobe rate; most of the benefits of strobing (LightBoost, ULMB, etc) tend to get lost when you are unable to run at framerates at least resembling stroberates.

For example, see http://www.testufo.com/framerates#count=3 on a LightBoost display
Observe that 30fps@120Hz (quad image efect) during LightBoost isn't as clear as 120fps@120Hz during LightBoost.
The same problem occurs on a 120Hz CRT, too.
It's not motion blur, but an annoying stroboscopic effect.

With strobe backlights, you need framerate == stroberate == refreshrate for the best motion clarity effect, without this artifact. This is where the sweet spot of CRT-like buttery-smooth effect occurs.
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HeLLoWorld
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by HeLLoWorld » 15 Jan 2014, 18:30

At 30fps@120Hz you should have gotten 4 trailing images as your eyes tracked things.
Not really blur, but a sharp alphablended sum of spaced ghosting pictures :)
You could call it blur if you move slowly and they are spaced just from 1 pixel.

edit : our guest beated me to it.

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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by Chief Blur Buster » 15 Jan 2014, 18:36

HeLLoWorld wrote:At 30fps@120Hz you should have gotten 4 trailing images as your eyes tracked things.
Not really blur, but a sharp alphablended sum of spaced ghosting pictures :)
You could call it blur if you move slowly and they are spaced just from 1 pixel.
Yes, that's true. You got that right!

It all varies, obviously. The bigger the disparity between strobing and frame rate, the more duplicate copies of images, and the more they start to overlap and resemble blur. And of course, if you use longer persistence (e.g. LightBoost=100% where there is 2-3 pixels of motion blurring), the images can be spaced 2-3 pixels apart and they would almost begin to blend together already, because of the longer motion blurring. Speed of motion, strobe length relative to dark period, number of repeat strobes, etc. The repeat image effect is just simply chopped-up motion blur (dotted motion blur). This becomes especially noticeable during higher-persistence strobing (e.g. BENQ XL2720Z reprogrammed to 4ms strobe using new firmware) -- so if you have a 50%:50% backlight flash duty cycles with 4ms persistence at 1000 pixels/sec, 30fps@120Hz -- single pixel thick elements would have a sequence of 4 pixels of blur, 4 pixels of black gap, 4 pixels of blur, 4 pixels of black gap, 4 pixels of blur, 4 pixels of black gap, 4 pixels of blur.

But yes, blurring verus duplicate-image-effect are kind of separate artifacts, but as you can see, they can start to blend into each other/overlap each other, especially as strobing is adjusted to longer-persistence and/or during slower motion, and/or strobing at a far higher frequency than frame rate, etc. To me, they are all artifacts that can only be beautifully eliminated when you have stroberates matching framerates.
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by RealNC » 15 Jan 2014, 18:36

Chief Blur Buster wrote:The same problem occurs on a 120Hz CRT, too.
This is pretty much the core of my question. So the answer is, the same effects that happen with low FPS on high refresh CRTs also happen on strobed high refresh LCDs?
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by Chief Blur Buster » 15 Jan 2014, 18:38

RealNC wrote:
Chief Blur Buster wrote:The same problem occurs on a 120Hz CRT, too.
This is pretty much the core of my question. So the answer is, the same effects that happen with low FPS on high refresh CRTs also happen on strobed high refresh LCDs?
Yep; repeat image effect is identical on both CRTs and strobed LCDs.
30fps@60Hz = double image effect
30fps@90Hz = triple image effect
30fps@120Hz = quadruple image effect

Doesn't matter how the display flicker (CRT, strobe LCD, plasma, black frame insertion, strobed OLED), you still want framerate matching flickerrate, to solve all blurring and repeat-image problems.

Your eyes are continuously moving as you track eyes. The strobing occurs at different points along your eye tracking trajectory (as old frames gets repeat flickers); creating the repeat image illusion. A close cousin is the phantom array effect and the stroboscopic effect, found in Science & References section of Blur Busters.
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by HeLLoWorld » 15 Jan 2014, 18:41

By the way Sir, as interesting as it may get, if things grow, you'll be overloaded by forum activity for one man when volume exceeds 24 hours in a day...

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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by Chief Blur Buster » 15 Jan 2014, 18:45

HeLLoWorld wrote:By the way Sir, as interesting as it may get, if things grow, you'll be overloaded by forum activity for one man when volume exceeds 24 hours in a day...
Enjoy while it lasts. Currently, this is the Golden Age of the Blur Busters Forum, small, fast moving, and high quality. I am, for now, giving lots of personal early attention to these forums (which launched only one month ago as of the time of this writing), to make it THE place on the Internet to go to, for all of this type of information. A bunch of game developers and display engineers are already visiting these forums, as we're the only forum on the Internet to actually specialize in these topics.

As the forum grows, there will be more smart members answering questions (for me) and more moderators (if any of you have big forum moderating experience, PM me with your moderator knowledge), to take over some of this forum workload. Also some of what I write here in this very forum, can be recycled into future permanent Blur Busters articles; saving me time in the future. The forum audience here is more intelligent than the average audience of many other mainstream forum already, or at least members that are easily teachable to the important concepts, and I would love to keep it (mostly) that way, at least by average, anyway. :D

The great thing is that a number of professionals / engineers / LightBoost lovers / certain really intelligent game developers / VR goggle developers / Oculus / John Carmack / Michael Abrash of Valve Software, are all of near unamious general agreement about the sensibility in the otherwise bleeding edge Blur Busters "Better than 60Hz" line of thinking relating to persistence -- (Even if approaches often differ on the end goals!)
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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by HeLLoWorld » 15 Jan 2014, 19:15

Thanks for your attention.
While I have it, may I ask where that funny alien of yours come from? Always makes me smile. It might go down in history :)

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Re: Need 1000fps@1000Hz for 1ms persistence without strobing

Post by Chief Blur Buster » 15 Jan 2014, 20:48

HeLLoWorld wrote:Thanks for your attention.
While I have it, may I ask where that funny alien of yours come from? Always makes me smile. It might go down in history :)
While I still have the rare time to actually answer these kinds of questions, here it is:
Blur Busters History: The Making Of the Blur Busters UFO.

EDIT 2018:
I've created an updated Blur Busters article about display persistence:
Blur Busters Law: The Amazing Journey To Future 1000Hz Displays
Go check it out, it's easier to understand than this thread!
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