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Glasses to emulate backlight strobing? [Mechanical Strobing Project WORKS]

Posted: 13 Apr 2021, 10:45
by liquidshadowfox
Are there glasses that flicker to emulate backlight strobing that can be used with any monitor (I know old Gsync monitors had the 3D effect that used special glasses with flicker).

Re: Glasses to emulate backlight strobing exist?

Posted: 13 Apr 2021, 15:06
by Chief Blur Buster
Yes, but very tricky to do good quality, as not all pixels refresh at the same time, plus GtG bleed between refresh cycles.

Related thread:
Chief Blur Buster wrote:
04 Oct 2019, 18:37
Lifestop wrote:This is probably a dumb question, but could strobing (sort of) be accomplished through the use of active shutter glasses (3d television) synced up with a pc display? Instead of blocking vision in one eye at a time for 3d, why not block both eyes for brief intervals to accomplish something similar to ulmb?

I'm not tech savy, but just a little curious after reading about how active shutter glasses work.
I'm answering in a "What if?" scientific matter of interest, rather than practicality.
Usually, when this question is asked, the original poster has a scientific curiousity, so here goes:

Short Answer: Yes

See old thread

Long Answer: It's yes, but with some tricky gotchas

1. You still need a fast display where the GtG is mostly complete in VBI between refresh cycles, see high speed videos

2. You need fast GtG in the shutter. LCD shutter glasses take time to open and close.

3. Synchronization with display refreshes. That can be challenging.

It also even works with mechanical wheels with holes in them. Running on a standard LCD, putting a desk fan in front of monitor -- shows some erratic motion blur reduction behaviours too (unsynchronized strobing). And old 1920s 3D movie experiments used mechanically-strobed 3D glasses:

Film projector strobing shutters (can be homebuilt/jerryrigged with home projector to reduce blur)

Mechanically strobed 3D glasses, circa 1920s experiment


An Ardino + motor can spin a wheel in front of an LCD/LCoS projector and successfully do ULMB with a projector. Don't do it with DLP because of its temporally-generated color, but it would work with LCD/LCoS projector technology. Two 5% slice removed from opposite edges of a wheel (need to keep it weight-balanced), spun 30 times a second for 60Hz (60 strobes) or spun 60 times a second for 120Hz (120 strobes), attached to a motor that is spun by an Arduino in sync to a VSYNC... and you get 90% motion blur reduction on an LCD/LCoS projector! (Though, with a 90% light loss).

If no VSYNC feed, have accurate analog knob for speed in 0.001 Hz increments, so you can do manual genlock the strobe by slewing the rolling artifacts until they were between refresh cycles (visual strobe-in-VSYNC calibration exactly much like how I use Blur Busters Strobe Utility on an XL2720Z). Might be able keep manual drift-readjustments to once every few minutes if your adjustments are fine enough and you eyeball a good motion-test-pattern. You could also use a USB-bus VSYNC feed (from a system tray app monitoring .InVBlank and transmitting those to the Arduino) and use some "noisy-VSYNC" filtering logic (similiar to the one ad8e provided for his C++ equivalent of Tearline Jedi) to filter the USB ping jitter to get the original VSYNC tick-tock. Stick to Arduinos with <1ms USB lag though.

Arduino-driven spinning-mechanical-wheel strobing works excellently with lowering persistence of sample-and-hold LCD/LCoS projectors. I've talked about this years ago too.

If anyone does a spinning-disc persistence-lowering device for LCD/LCoS device, please post here. It's a fun cheap Arduino experiment.

Tips for external strobing devices (glasses, mechanical):
- Manual genlock mode (need to be able to speedup/slowdown in tiny increments with an analog knob)
- VSYNC trigger genlock mode (listen to an external VSYNC signal on a GPIO pin)
- Phase offset adjustment (flash position relative to VSYNC position)
- Length variable (slit size on spinning wheel, or shutter length for active shutters)
- For rolling shutters, roll the shutter downwards, in sync with rolling scan, for best results. Most LCD/LCoS microdisplays use a downward sweep,

Re: Glasses to emulate backlight strobing exist?

Posted: 13 Apr 2021, 21:50
by liquidshadowfox
Do you happen to know what's the max refresh the 3D vision glasses from nvidia support? I see the guys post from the bottom of that forum post that mentions a program that can change timings but I'm not sure if it can change the timings to accommodate 240hz or 120 hz and keep both lens in sync (cause I know they usually alternate). I'm very interested in making a pair of glasses for this as I have already found that using a fan actually reduced motion blur by a LOT on my samsung G7, Especially at 60 and 120 fps on ufo test.

I know backlight strobing is great on monitor but sadly the backlight strobing on the G7 isn't good and there's no way to really edit the strobing on it. My proposed solution is this:
1. Have glasses with either some fan in front of it (wacky) or active shutter lcd that can go opaque fast enough (I'm hoping for at least 120 or 144 hz but I don't know if the technology exists yet)
2. Hook it up to a small arduino board with low latency wireless usb to communicate with desktop PC to report in game FPS to sync with
3. Have riva statistic tuner running to keep good frame pacing and enable specific framerate per game
4. Firmware on arduino board to change the stutter or fan speed based on the FPS of the game. Gsync should reduce refresh of monitor to match fps in game.

Issues I have currently
1. Don't know where to find the lcd to use as active shutter
2. Don't know how I would create lenses with fans embedded.

I feel like monitors are getting brighter and brighter every generation but personally I feel like anything above 500 nits just sears my eye balls! So why not take advantage and use glasses to block out most of that bright light and get a semi decent strobing experience on monitors that either don't support it (I'm looking at those LG nano IPS panels with red phosphor, this would in theory be a good alternative given how good the response times are) or have really mediocre none editable backlight strobe (Samsung G7 as an example) and don't even support variable refresh strobing.

I would love to see someone's project or concept of this if it exists!

Re: Glasses to emulate backlight strobing exist?

Posted: 15 Apr 2021, 22:29
by Chief Blur Buster
I have a better idea for you, that is actually more successful: backlight hacking.

Glasses strobing is way worse than backlight strobing, due to additional weak links. Recall they actually ADDED a strobe backlight to reduce crosstalk for glasses strobing? For a partial explanation why, press “play” on all videos at

Blur Busters started due to an Arduino scanning backlight project —

It is easier to improve backlight strobing quality by hacking an LCD backlight instead (attach it to an Arduino like the XL2546 hacker did for 60 Hz strobing), combined with improved GPU-based overdrive to reduce strobe crosstalk.

Re: Glasses to emulate backlight strobing exist?

Posted: 16 Apr 2021, 14:06
by liquidshadowfox
Backlight hacking looks and sounds great but I wouldn't want to void my warranty hacking the backlight on my expensive samsung g7.

I used a simple desk fan and it was more than enough to reduce the blur without any noticeable crosstalk (as a matter of fact the image looked clearer than samsung's own implementation of backlight strobing! lol) . Although I agree with you that glasses strobing will be worse than backlight strobing (properly implemented backlight strobing of course) I feel like it's actually "good enough" vs poorly implemented backlight strobe. I don't know for sure if the desk fan principles will carry over to a flickering transparent screen slapped on some glasses but I will do my best to at least try. I still see value in the existence of such glasses simply because it could in theory bring some sort of strobing to any monitor (Think LG Nano IPS displays that can't strobe well due to red phosphor as an example).

I have never seen a clearer image of the ufo test @ 60 fps or 120 fps until I used a desk fan and that within itself I think is amazing. I also would like to say I am not an electrical engineer :) So I am also starting from scratch, just a computer scientist who has a deep fascination with low motion blur technologies.

In case you are curious and happen to have a samsung G7 laying around.... (I'm sure you know more about this than me but it's really funny to see a desk fan out perform a backlight strobing mode on samsung's flagship monitor)

The fan I bought from amazon was the OPOLAR 10000mAh 8-Inch Golf Cart Clip on Fan with built in battery and I used the slowest speed setting.

Re: Glasses to emulate backlight strobing exist?

Posted: 16 Apr 2021, 18:23
by Chief Blur Buster
If you want to try external method of strobing, I recommend:

1. Mechanical strobing method with a top-to-bottom rolling scan.
It becomes an external “scanning backlight” that is vastly superior to a scanning backlight, since it doesn’t have internal light diffusion (ON light segments leaking light into OFF segments).

2. Avoid shutter glasses because of dissapointing results
Shutter glasses have an LCD GtG pixel response (glasses are 1-pixel screens per eye). Use actual mechanical shutters (like a fan) because of instant 0ms GtG of moving physical shutter edges.

3. Try a synchronous motor connected to an Arduino for a rolling shutter
With a spinning disc with a slit in it that spins downwards in sync with the top-to-bottom LCD scanout.

To avoid crosstalk, you want to have the top-to-bottom rolling scan slit open only for the checkmarked areas (clearest LCD scanout portions), as follows:

Your recipie will be:

1. One good Arduino

2. Synchronous motor (or two) controllable by the Arduino

3. Mechanical disc (or two) with a slit in it.
3a) Single motor/disc: You need a slit long enough to fit both of your eyes (large spinning disc)
3b) Two motor/discs: You need two counter-rotating motors (alongside each other, but rotating slits downwards on the inside spin) to spin the smaller slits downwards, the left-eye motor spinning clockwise to spin the rolling shutter slit downwards for your left eye — and the right-eye motor spinning counterclockwise to spin the slit downwards for your right eye.

4. Method of adjusting tracking (motor frequency) and phase (motor timing relative to refresh cycles).
4a) Manual frequency: rotating potentiometer knobs to adjust frequency / phase of the spinning motor. There will be slow drift, with slowly appearing/disappearing crosstalk, so you will have to readjust once in a while (in literally ~0.001Hz-ish increments) by eyeballing motion tests such as — adjusting knobs until that test looks clearest.
4b) Automatic frequency: Software-based flywheel algorithm to automatically sync frequency via a VSYNC signal transmitted over jittery USB to the Arduino (from a system tray utility monitoring D3DKMTGetScanLine() Windows API call, to monitor the .InVBlank events).

The huge advantage of rolling-scan mechanical shutters (like a spinning-slit projector shutter or a spinning-slit high speed camera shutter) is that they
(A) have instant 0ms GtG at the leading and trailing edges, unlike LCD shutter glasses, and
(B) can be synchronized in a way to avoid revealing the LCD’s own GtG fadezone (the crosstalk problem area).

1. Learn about “rolling shutters”. They’ve been used for years in analog film high speed cameras and are still used for ultra-fast exposures with a SLR camera. They were also used for 35mm projectors (180-degree shutter)
2. Learn about how to sync a synchronous motor with an Arduino

Bonus: This works with LCD / LCoS / SXRD projectors too! You can use a spinning disc to strobe a LCD / LCoS / SXRD projector to reduce display motion blur. (Doesn’t work well with DLP projectors due to color depth loss from interrupted temporal dithering).

As Blur Busters — of all motion blur busting fame — love this kind of stuff. Here’s an offer: For someone reputablewho wants to elect to build such a beast, and have good looking cred, I would donate a high-performance USB2 Arduino compatible plus some goodies to help sponsor the costs of basic materials for this project if (A) open sourced, and (B) Blur Busters can write an article about it.

This cool stuff is right up Blur Busters’ alley.

Do you have software development experience? I can help with certain necessary Arduino API’s, and Windows API’s necessary to get this Rube Goldberg contraption to work successfully (with reasonably low-crosstalk motion blur reduction).

Re: Glasses to emulate backlight strobing exist?

Posted: 16 Apr 2021, 22:16
by liquidshadowfox
Yes I have software development experience. Currently a dev ops engineer :P

Preferred programming languages (from most liked to least):
1. Golang
2. Java
3. C#
4. C++
10. Javascript (I hate javascript)

but I'm willing to learn and pick up any language we would need for this type of project. My plan was always to make this sort of thing open source, after checking out the low motion blur of a silly fan I can't imagine not making this available to everyone :) I don't mind blur busters writing an article about it either, that'd just be a nice bonus and I am a researcher at heart which is why this site really resonates with me. I probably understood at least 40% of what you said in your reply so I'll have a lot of homework to do. I welcome any help you have to offer and wouldn't be afraid of chipping in some $$ just to make this a reality. I'm also open to learning anything you have to offer as I love learning about all this low motion blur tech and teaching my gaming friends about it. I actually had a friend who chose to turn off Gsync forever after I taught him and showed him the difference low motion blur could have when playing video games.

Re: Glasses to emulate backlight strobing exist?

Posted: 06 Jun 2021, 18:16
by liquidshadowfox
Hi, wanted to let you know I've been busy the past few couple of months with life and such but I've been working on doing some research on those shutter glasses you mentioned. Would love to see a drawn picture or diagram of how the glasses should look with rolling shutter going from top to bottom, I can't visualize it. I also send you a pm whenever you get a chance to take a look at it

Glasses to emulate backlight strobing? [Mechanical Strobing Project]

Posted: 09 Jun 2021, 15:37
by Chief Blur Buster
liquidshadowfox wrote:
06 Jun 2021, 18:16
Hi, wanted to let you know I've been busy the past few couple of months with life and such but I've been working on doing some research on those shutter glasses you mentioned. Would love to see a drawn picture or diagram of how the glasses should look with rolling shutter going from top to bottom, I can't visualize it. I also send you a pm whenever you get a chance to take a look at it
First, before you visualize things from the shutter glasses side, it's useful to get familiar with how LCD screens refresh first.

There's a study sequence:

The Basics of LCD Pixel Refresh
1. Remember that not all pixels refresh at the same time. That's the main problem. You want to hide pixels (from eyes) that are still mid-refresh.
2. LCD refreshes pixels from top to bottom.
3. LCD pixel transitions are simply pixels "fading" from one color to the next.
(GtG = Grey to Grey transition, on per subpixel basis. LCD pixels are monochrome and are simply color-filtered)

View the high speed videos at

phpBB [video]

This is an ultra high speed video of TestUFO Scanout which is simply a test that swaps between 4 different frames. You can film this with any recent Samsung Galaxy (S9, S10, S20), nearly all of which have a 960fps ultra high speed filming feature. Or any of the phones with the Sony camera sensor (e.g. Sony Experia XZ Premium), which can be purchased for as low as $200 as one of the cheapest high-def 1000fps-league video cameras available for DIY display research.

When seeing these videos, you begin to realize that if you strobe the LCD while it's still halfway refreshed, you will have artifacts. You need to strobe only the visible-parts of the LCD. For global strobing, you simply flash when the scanout sweep is between refresh cycles (as much as possible). For scanning-strobing, you strobe only the clear parts of the LCD (hiding the mid-refresh parts of the LCD from your eyes)


Your goal of a mechanical rolling shutter is to hide the GtG fadezone away from human eyes. So your spinning shutter only sees the fully refreshed parts of the screen surface, such as right above the GtG fadezone (the blurry top-to-bottom wipe effect) you see in high speed videos. This avoids seeing the worst strobe crosstalk.

Mechanical Scanning can be superior to Backlight Scanning
If you read the old Blur Busters Scanning Backlight FAQs from 2012-2014, you'd know the disadvantages of a scanning backlight from internal backlight leakage (from ON segments leaking into OFF segments), creating crosstalk from scanning backlights. Mechanical rolling shutters theoretically produce superior strobing than scanning backlights because you're avoiding internal backlight diffusion. So mechanical rolling shutters are potentially an ideal way of creating low-persistence OLED/LCD/LCoS or other sample-and-hold display that's not using temporal dithering (aka not a DLP).

Now, the problem is you want both eyes to be scanning downwards simultaneously.

The problem with one centered wheel
If you use one wheel centered in front of your eyes, one eye will scan upwards, and the other eye will scan downwards. The down-scan will be fine, but the up-scan will artifact on the other eye (seeing the GtG fade zone). You don't want the GtG fade zone to be visible to eyes. So you want either two synchronous wheels (centered on the outside edge of your face), or one larger wheel (offset at edge of your face) to allow both eyes to simultaneously see a downwards-scanning slit.

I am creating rough diagrams for you now.

Re: Glasses to emulate backlight strobing? [Mechanical Strobing Project WORKS]

Posted: 09 Jun 2021, 16:15
by Chief Blur Buster
Just created diagrams.

Option 1: Two Shutters

1. Similar behavior for both eyes
2. Vibrations cancel each other out with fast contra-rotating motors (3600 RPM at 60Hz unless you use multiple slits per wheel, see below!)
1. Requires two synchronous motors (or one center motor with gears to the two side wheels)
2. Movement of head will produce mis-sync artifacts.



Option 2: One Shutters

1. Simpler to build.
1. Offset weight
2. Offset vibrations may make for uncomfortable viewing.
3. Movement of head will produce mis-sync artifacts.



Option 3: Table Edge Mounted Shutter (RECOMMENDED)
1. Easiest to build, fewer components, can use a vise to hold apparatus
2. Vibrations won't interfere with your head
3. Position can easily be calibrated (movement of monitor + shutter to ideal positions), removing the human-head-position uncertainity
4. Compatible with projectors too (putting it in front of projector lens, then everybody can view the same low persistence on the screen)
5. Easier to calibrate head-to-wheel distance simply by moving head closer/further away from wheel.
6. More comfortable
1. Not wearable

This is the RECOMMENDED technique for mechanical strobing of a display

I super-strongly recommend option 3 as a starter build -- more than 10x easier to succeed. Plus more flexible/modifiable for different displays & even use for projectors too!

- Make sure you design your wheel big enough to accomodate both eyes.
- A 12-inch-wide wheel should suffice.
- BONUS TIP: You can add multiple slits to the wheel (2 slits) and simply spin the wheel at half speed, if you're concerned about off-center-gravity vibrations. So one slit at the left/right edge of the circular rolling shutter.


Warning: This Does Not Solve All Problems

Instead of 1 slit you will need multiple slits so that you can slow-scan downwards at a velocity similar to the refresh scanout. You'll probably want maybe 3 or 4 or 6 narrow slits per wheel (applies to any of the 3 options above) so you can view through the slit closer, you will need to experiment with slit position so that your rolling-shutter velocity roughly matches the top-to-bottom scan velocity, and you'll probably need separate wheels for different Hz for this very reason.

Alternatively, you could work from the reverse direction (choose a horizontal-scanrate-multisync panel and then optimize scanout velocity (of a multisync panel) with Large Vertical Totals to speed up / slow down the scanout of a panel to match an unmodifiable strobe wheel).

Rolling shutters is what many old 35mm movie projectors do to hide the blur of the filmreel moving from one frame to the next.
(Google Images Search). You're simply commandeering this technique to hide the GtG fadezone while lowering the persistence of a sequential-scanout sample-and-hold display.

When using this method to do low-persistence of an LCD or OLED, you will need a much narrower slit than what film projectors use. Slit width as percentage of the distance to next slit, will be your persistence percentage. As a boilerplate recommendation, I recommend 10% persistence, so your wheel's rotational surface area will be 10% slit by surface area. Due to the way human vision cones out, it may a 10% slit may actually end up closer to 20%-30% persistence.

If you cut all the way to pretty close to center, make sure to cut slits out in pie-style, not straight slits, because outer parts will scan faster than the inner part. Now, if you need extra structural, don't cut slit all the way to center but closer to a Phenakistoscope wheel (but with longer slits).

Also, when viewing through the slit, view the slit from a few inches away, rather than extremely close to the slit. You'll have lots of fun testing head-to-wheel distance.

Optimization: Use Multiple Slits Per Wheel

You want one slit scrolling past per refresh cycle, which means a 1-slit wheel needs to spin 3600 RPM for 60Hz displys, or 7200 RPM for 120 Hz displays. So you'd need a very strong wheel, and it might get dangerous.

The fewer slits you have (or just 1 slit), you will need to spin the wheel slower.

For a 60Hz display:
- A 1-slit wheel spins 60 cycles per second (3600 RPM)
- A 2-slit wheel spins 30 cycles per second (1800 RPM)
- A 3-slit wheel spins 20 cycles per second (1200 RPM)
- A 4-slit wheel spins 15 cycles per second (900 RPM)
- A 10-slit wheel spins 6 cycles per second (360 RPM)

The more slits, the easier it will be because of:
- Slower motor spin speed
- Easier to get the picture brighter with less crosstalk and fewer artifacts
- More of the screen will be hidden more reliably with close human-head-to-wheel viewing distance, because of narrower slits.
- A smaller wheel is possible with more slits because you're more easily able to put your head closer to the spinning wheel.
- Viewing the slit too closely will cause you to view too much of the screen surface. And you're forced to use a bigger wheel when you're using a more distant viewing distance.

TIP: Optimize To Slow Wheel Speed So You Can Use Simple CARDBOARD
If you use enough slits, you can spin slow enough to just use simple cardboard or construction paper for strobe wheel!

(Just like a DIY Phenakistoscope / Zoetrope / Etc project.)

Cardboard shutter wheels are common in other non-display projects, as they are based on the 19th century invention of moving pictures. You're just commandeering this technique for mechanical strobing of an LCD display. Thinner slits were well known to darken picture but make motion clearer (less motion blur) -- slit size optimization is an art of the 19th century which you will still need to do in the 21st century for mechanical strobe for display motion blur reduction.

phpBB [video]

Except with a strobe wheel:
- You use the same cardboard wheel but with NO PICTURES
- Instead, you view a display through the cardboard wheel.
- If you are starting out can begin with small slits only suitable for one eye (for simpicity) before going to larger wheels or double wheels (for both eyes).
- The great thing about cardboard is you can keep trying and trying with different slit sizes and wheel sizes.

Optionally, if you have difficulty visualizing how to fix problems, then if you want to speed up debugging, I highly recommend a 960fps high speed camera. I don't need it because I am good at visualizing displays (my head can emulate display algorithms -- that's how I invented some TestUFO patterns) but not everyone can do this.
- Almost any Samsung Galaxy S9, S10, S20 can act as your 1000fps high speed camera.
- A cheap Sony Experia XZ2 Premium from eBay for about $200 if you just want a cheap 1000fps HD camera for DIY display engineering.
- You can use this on the display (to ascertain its scanout behavior)
- You can use this with the spinning wheel (to double check spinning velocity and sync with display).

Bottom line for easier flexible debugging:
- Table mount method
- Larger-than-necessary 18+ inch wheel (much more flexible)
- Many more slits (that only begins about ~3 inches outwards from the wheel center, to keep wheel center strong), perhaps 10 or 20 slits so your spinning speed is within range of cheap motors.
- With a slow enough spin speed, you can just use cardboard or construction paper & an exacto knife!
So you can build many different wheels with different slit sizes and different number of slits.

Recommended Easy Journey

1. Table edge mount with a vise or modified VESA mount pole.
2. At least 10 slits, to keep spin speed slow and allow use of cheap cardboard
3. Experiment with a few wheels with cheap cardboard + scissors/Exacto knife, so you can repeatedly experiment with different wheels.
4. Begin with direct motor power (analog potentiometer for motor speed control) and calibrate the spin speed manually.
5. Only after then, start adding an Arduino to control motor speed (may need to swap motors to one you can control exact speed of)