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Mechanical shutters for motion blur reduction & 3D [works!]

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Mechanical shutters for motion blur reduction & 3D [works!]

Postby James Freeman » 25 Jan 2014, 05:54

I'll continue here instead of creating another thread.

I have made a low-tech shutter whith a PC case fan with the blades cut off, custom cardboard shutter, pot to control the speed, I hold it in front of my eyes. :oops: ... till my electronics arrive.
I calibrated the speed with the Test UFO site.
Works like charm but though to catch the exact frequency.

What I have noticed is that when playing a lower frame rate content (a 24fps movie) and flashing it twice (48) or three times (72) like in the cinema, I see no eye tracking blur, but image doubling or tripling (lets call it "Image Multiplication").

Then I calibrated my low-tech fan to 24 flasher per second and everything is perfect, a single sharp image.
BUT, it flickers like nobodies business... that means that Cinema with double or triple flash is also suffering from "artifacts" (image multiplication), which means that even in theaters the experience is not ideal.

After these tests I conclude that:
The only way to see ANY content without motion blur, eye-tracking blur or image multiplication, is at its native frame rate and strobed.
Even if it means 24fps @ 24Hz...Its bad believe me.

If anyone wonders, yes, a 24fps movie (blu-ray) on a 120Hz strobbing monitor, will look just like a low frequency backlight PWM artifacts or image multiplication (same thing),
aka it will not be blurred but it will look like 5 images one on top of the other with a small gap between them.
Besides, nobody actually knows/sees/cares what sample-and-hold blur looks like till they see the same content without it...
And, oh boy... I'm hooked to say the least, even if it destroys my eyes/brain at 24Hz.

In a hundred years nobody complained about the horrible 24Hz-single-flashing-shutter at the cinema, there for I will also not. :lol:
The movies are "Flickers" for a reason you know...

Here are Film Projector Shutters for example (Single, Double & Triple flash):
Image Image

What do you think, will we ever see a low frame rate content without eye tracking blur AND without visible flickering?
I personally don't think so (its physically/humanly impossible), Its 24fps at 24Hz strobed, or BLUR. :twisted:

BUT, there is a positive side to this.
A 24fps @ 24Hz Strobed (or BFI) looks like its high frame rate because of the Eye/Brain Tracking effect.
I think the brain somehow completes the missing information and makes the image looks A LOT smoother.
Once I actually got used to the horrible 24Hz flicker (takes about 10 minutes, yes, your brain gets used to this), I got the most smooth cinema experience I have ever watched.

A picture to demonstrate:
24fps strobed.png
24fps strobed.png (2.88 KiB) Viewed 6558 times



P.S
Mark, Can you please add an option in testufo.com to select a Custom UFO framerate in the "Framerate" tests.
For example: I want to see how 24, 30 looks on a my 72Hz screen, but I only see 72, 36, 18 ,9 etc (divisions of 2)...
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Mechanical shutters for motion blur reduction & stereo 3D

Postby Chief Blur Buster » 25 Jan 2014, 16:23

Mechanically-assisted motion blur reduction! Yep, it definitely works -- staring through a spinning desk fan to look at the computer monitor, actually has less motion blur than without. If you got it to sync up with the refresh, you've got mechanically assisted strobing.

This reminds me of the 1922 mechanical 3D shutter glasses experiment:

Image

You should attempt to do 3D Vision with your mechanical shutters, and if 3D Vision works with it, then I'd love to write a small Blur Busters article about the history of shutter glasses, to put on the main website. Reproducing the mechanical shutter glasses viewer almost 100 years later.

James Freeman wrote:Once I actually got used to the horrible 24Hz flicker (takes about 10 minutes, yes, your brain gets used to this), I got the most smooth cinema experience I have ever watched.

Back in the late 19th century and early 20th century, they had to tolerate single-strobe per frame.
But eventually, that went the way of double-strobe to reduce flicker, at the expense of adding motion artifacts (double-edge artifacts during panning).

P.S. Because of the change to mechanical shutters, I truly think this belongs in a new thread, if you don't mind me moving these posts. The funny thing is that this is technology that has been worked on for over 100 years but few people understand how motion clarity went out of the window over the years, and they are now addressing it with various techniques including VR, low-persistence, HFR, strobe backlights, interpolation, etc.
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Mechanical shutters for motion blur reduction & stereo 3D

Postby Chief Blur Buster » 25 Jan 2014, 16:25

James Freeman wrote:P.S. Mark, Can you please add an option in testufo.com to select a Custom UFO framerate in the "Framerate" tests. For example: I want to see how 24, 30 looks on a my 72Hz screen, but I only see 72, 36, 18 ,9 etc (divisions of 2)...

Sure, though there will be stutters when frame rates are not divisible by Hz.
I will attempt to have the new test up and running within a week: possibly named as "Framerates Versus"
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Mechanical shutters for motion blur reduction & stereo 3D

Postby HeLLoWorld » 25 Jan 2014, 21:51

abour the ufo tests, while I think of it, the other day I thought it might be better in some cases to have an option to make all translation tests bounce on left/right edges rather than start again at the left edge, from the point of view of eye-tracking ease.
Either a hard bounce (velocity = 0 - velocity) or some sinusoidal law (probably too slow when it bounces) or modified sinusoidal ( like a bounce, but softened when it bounces (I understand it means speed is not constant anymore but it can be constant 90 percent of time, smoothly bounce and be constant again).
Not sure if I'm clear but it can be tedious re-syncing the eyes to the ufo at the left each second while tracking it.
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Mechanical shutters for motion blur reduction & stereo 3D

Postby HeLLoWorld » 25 Jan 2014, 21:57

Or if you got time to waste the movements could be circles :) but then the exact pixel count per frame is not as clearly defined since there's a variable 2D vector associated with each frame.

I especially think about the eye-tracking motion blur, you got only a fraction of second to resynchronize on left edge and the thing has already moved much, and then you got to keep some mental focus on the background too. For this one I think even a hard bounce might be way better already.
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Re: DIY Backlight Strobing [must read for experimenters!]

Postby James Freeman » 26 Jan 2014, 01:41

Chief Blur Buster wrote:P.S. Because of the change to mechanical shutters, I truly think this belongs in a new thread, if you don't mind me moving these posts. The funny thing is that this is technology that has been worked on for over 100 years but few people understand how motion clarity went out of the window over the years, and they are now addressing it with various techniques including VR, low-persistence, HFR, strobe backlights, interpolation, etc.


No problem, you can move this post to a new thread.

Yeah, out of the window big time.
Be careful people, once you see blur-free movie/gaming with your own eyes, you can't go back. :lol:

Thank you very much for the "Frequency Versus" option in TestUFO.com.
It'll be very nice to have an option of selecting between an Alien (or several),
and a Vertical White Line at full screen with variable fps and speed, for tear tuning.

About shutters,
My current objective is to modify an Active Shutter 3D Glasses to open and close according to a Square wave Generator (with PWM).
The Signal Generator that I have bought has resolution of 0.01Hz & 1-99% PWM at any frequency (that matters),
so it would be no problem fine tuning it to the display Refresh Rate, controlling strobing rate, finding tear free region (delay).
To tune the square wave delay (phase) to a tear free region, I'll just need too add a few Hertz (or milliHertz) till I'll see the tear in the white line moving vertically, once I'm satisfied with the position of the region, I'll revert back to the original frequency "on the fly".

From what I've seen with my mechanical shutter, my monitor has about 5cm (2 inches) of tear free region (@72Hz) because of the small amount of the blanking pixels and the slow response time of the AMVA panel, even slower than IPS.
That's a bummer, but not to worry, it is a vital experiment for my knowledge.
Last edited by James Freeman on 26 Jan 2014, 01:56, edited 1 time in total.
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Re: DIY Backlight Strobing [must read for experimenters!]

Postby Chief Blur Buster » 26 Jan 2014, 01:52

James Freeman wrote:From what I've seen with my mechanical shutter, my monitor has about 5cm (2 inches) of tear free region (@72Hz) because of the small amount of the blanking pixels and the slow response time of the AMVA panel, even slower than IPS.
That's a bummer, but not to worry, it is a vital experiment for my knowledge.

Indeed, I have witnessed a similar issue (less pronounced) when its blanking interval was small. I noticed I reduced strobe crosstalk (double-image effect) because of incomplete LCD pixel transitions leaking into the subsequent refresh cycles. I was able to eliminate a lot more of the strobe crosstalk using the newer firmware by using a huge blanking interval (1350 Vertical Total for 1080p) which creates a 2 millisecond pause between refresh cycles, big enough to let TN pixels mostly settle.

LightBoost and ULMB uses FIFO buffering of the input for a partial frame, and then does an accelerated scan out, artificially creating the longer blanking interval. So it has reasonably low strobe crosstalk, on average.

You could also obtain a cheap high speed camera ($150 for an entry level consumer 1000fps such as Casio EX-ZR200 at low resolution 1000fps at 224x64, and 480fps at 224x160) for display analysis; it is an additional tool in the Blur Busters league of experimentation.
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Re: Mechanical shutters for motion blur reduction & 3D [work

Postby James Freeman » 02 Feb 2014, 12:54

Mark,

May I suggest to include the strobe rate == frame rate == refresh rate law in the Artifact 101 section of the main site.?

People need to know that when the frame rate (assuming its an even division of the refresh rate) is not equal to the strobe rate, the picture will look like PWM artifacts or "image repeating" as you call it on the PWM section.

For example:
24fps movie on a 120Hz+Strobing monitor will look like 5 repeated images.
30fps games on a 120Hz+Strobing monitor will look like 4 repeated images.
Which is equally as bad for image sharpness & discernibility as eye-tracking blur (motion blur), but different.

I think it is important knowledge for people who plan to buy a strobing monitor.

P.S
Do you remember the custom frame rate on the testufo.com site we talked about?
I still can't find a test that will give me 24fps/30fps alien/line on my 72Hz monitor to test.
It'll be nice to see this in the "Moving Photo" section to show people how 24/30 fps looks like on their monitor in terms of blur/repeating (strobing or not).

A simple: "Image FPS" = Refresh/X (X=1,2,3,4,5,) should do it.
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Re: Mechanical shutters for motion blur reduction & 3D [work

Postby Chief Blur Buster » 03 Feb 2014, 21:30

James Freeman wrote:May I suggest to include the strobe rate == frame rate == refresh rate law in the Artifact 101 section of the main site.?

A new, separate article will be written in the near future that covers the "zero motion blur nirvana", "butter smooth motion", "CRT effect" -- and this 'Law' of motion clarity will be part of it.
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