Is motion blur directly related to strobe visibility or not?

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Re: Is motion blur directly related to strobe visibility or not?

Post by Chief Blur Buster » 29 Mar 2021, 16:19

MCLV wrote:
29 Mar 2021, 15:52
I think it really depends on the application. I'm not sure that it's so clear cut and that uncanny value is always that wide. 24 fps has definitely it's own look but I have to say that I've never considered it good looking in certain situations, e.g. panning shots. I made my own comparison of 24, 30, 60 and 120 fps video few weeks ago. 24 fps looks great when camera is static but falls apart during panning. Higher framerates look progressively better during panning. However, it was not completely apples-to-apples comparison since I recorded 24 and 30 fps in 4K and 60 and 120 fps only in 1080p. Unfortunately, I don't own any device capable of recording 4K at 120 fps.
While a good personal experience sample -- I just want to point out that you missed a very important point about widest-population satisfaction (which is definitely not opinion, but actual research).

For engineering the entire display experience for the population, this is not one of the situations where you can use only one person's personal experience. This is a human population based matter.

Consider the use case of staring at a huge IMAX screen. Consider the people who get motion blur nausea.

To get as much five-sigma comfort as possible (least numbers of motion sick from the widest numbers of human population), you have to push the framerate really low OR really high.

The % of motion sickness cases increases with wide-FOV intermediate-framerate sample-and-hold HFR because you're getting a wide reallife FOV, but you're still getting camera motion blur or display motion blur enforced upon your human eyes.

This was traced the fact that motion is now smooth (no stutter / edge flicker) to help you suspend disbelief, but now you're eyetracking still-blurry motion.

It doesn't mean the satisfaction rating of a one-person sample (like you) when it comes to sample-and-hold HFR. Motion-blur-nausea and motion-blur-induced motion sickness is getting more well known in the last few years, and is Elementary VR Comfort 101 now -- any good VR researcher know about this already.

Since people started wearing the first Oculus Kickstarter VR headsets and got puke/sickness from sample-and-hold, but magically disappeared when Oculus strobed the display.

For the Motion Blur Uncanny Valley Effect, Set Variables To The Following

Size = Wide Field-Of-Vision (FOV) Displays (VR, IMAX, simulator rides, sit close to screen, etc)
Tech = Sample and Hold (LCD, OLED without strobe/flicker/BFI/PWM-free/impulsing)
Resolution = Retina (4K and up)
Sample = Human Population
Goal = Satisfy Widest % Without Motion Blur Nausea

When these variables are configured, the motion-nausea uncanny valley effect appears. The best display comfort (lowest % of motion sickness) occured at these:
  • Low frame rates (i.e. 24fps)
  • Ultra high frame rates (i.e. 500fps or 1000fps+)
Intermediate framerates had the problem of looking smooth but still blurry. When viewed wide-FOV (like VR wraparound display or IMAX display), this sample-and-hold blurring becomes very nauseating, like unwanted artificial motion blur added to real life above-and-beyond human vision.

Unless you changed the "Tech" variable to strobing the display (e.g. 120fps at 120Hz), to fix persistence motion blur of 120fps HFR.

Reports of dizziness, headaches, nausea, were pretty common during head turns on the original Oculus Kickstarter DK1 VR headsets (sample-and-hold VR), until the Oculus Development Kit 2 (strobed pulsed OLED) and the first Oculus Rift CV1 units, where strobing added another order of magnitude (or two) reduction in population discomfort of VR. The same effect is also observed for other kinds of wide-FOV displays other than VR, too.

Some will always get motion sick, but smaller % of population does at the ultralow and ultrahigh ends, with these variables, reduced motion sickness from the immersion-disengage-effect of low frame rates, and reduced motion sickness from blurless flickerless motion (from ultra high frame rate low-persistence sample-and-hold).

This is why 24fps and 1000fps has fewer headaches than 120fps sample-and-hold HFR (where you still had a mandatory 1/120sec = 8.3ms of display persistence = 8.3 pixels of guaranteed minimum motion blur per 1000 pixels/second = 64 pixels of motion blur during one screenwidth per second panning on 8K sample-and-hold display for 120fps HFR.

When you need to design something you need to sell to the wide-FOV market (VR, IMAX, ride simulator, etc) and you don't want your population to become dizzy, then what I am saying here is exceedingly critical -- it's already mandatory VR Engineering 101.

Today, thanks to switching from sample-and-hold to strobed/pulsed operation, modern VR has now become much comfortable than cinema 3D glasses, and almost anybody can put on a VR headset for an Oculus "Comfortable-rated" app (i.e. virtual lounger on virtual beach, rather than sitting on a rollercoaster), and have far less discomfort than watching a 3D cinema movie with traditional polarized glasses. The motion blur (even of 90fps or 120fps HFR) was the bigger motion-sickness poison relative to the flicker of strobing.

This stuff is so recently studied that new research papers are still being written for the first time on this, but needlessto say, it is currently now widely known in the VR-headset researcher community.

So for large-population comfort for wide-FOV use cases:
  • Extremely low frame rate sample-and-hold (like 24fps cinema/IMAX/ridesim screens)
  • Ultrahigh frame rate sample-and-hold (low persistence without strobing)
  • Strobed framerate=Hz beyond flicker fusion threshold (low persistence via strobing)
Large-FOV tends to be reality-simulation use cases, and the uncanny valley effect is caused by (A) screen becoming a simulation of reality from sheer large-FOV, and (B) motion blur from the combination of sample-and-hold and camera blur, and (C) frame rates high enough to look smooth instead of stutter to help you decouple a display from real life, and (D) sample-and-hold frame rates that are too low "low persistence sample-and-hold". When you combine (A)+(B)+(C)+(D) simultaneously (a problem for VR as well as sitting near giant-FOV 2D screens).

There will always be people who always gets motion sick, but a smaller % of humans gets motion sick when you push framerates lower or higher on sample-and-hold displays, due to "motion is smooth but still blurry" odd effect.

Remember, also, not every human eyes or brain sees the same. Prescription glasses. Color blindness of varying degrees. More sensitivity to stutter than blur. More sensitivity to blur than flicker. More sensitivity to flicker than blur. Brain-processing quirks such as dyslexia (or the motion-sensitivity brain processing flaws such as the varying degrees of Akinetopsia). Different color primaries (e.g. one human seeing brightest red at +10nm different primary than the next human; remember color gamut standards are based off an average human's primary color abilities, but even non-colorblind humans sees colors ever slightly different from next human, like no two snowflakes are perfectly identical). Vertigo (eye-hand-coordination problems). Brightness oversensitivity. Headaches from excess contrast or bright colors. Etc. Etc. There's so many quirks by humans from displays being imperfect simulations of real life.

Sometimes, we have try our goddamndest best to five-sigma display comfort. (Five-sigma tends to be impossible, it's more like three-sigma, but always perpetually refineable)

Wide-FOV blends a display into real-life, and when a display does not match real life (i.e. display persistence blur above-and-beyond human vision/brain limits), a larger percentage of humans gets dizzy/nausea. The low frame rate makes it easier to decouple dispay-vs-real-life. But once frame rates starts going high enough (60fps) where the stutter-to-blur continuum becomes blur instead of stutter -- the human brain starts processing a wide-FOV display as if it's real life. But sample-and-hold HFR (even at 120fps) still has stupendous amounts of motion blur (also amplified by Vicious Cycle Effect), which becomes a major problem for high resolution wide-FOV displays. Thus, "motion is perfectly smooth" + "motion has motion blur" = very oddly different from real life. Not good for VR/IMAX/ridesim/cinema first-row-of-seats/etc use cases -- cue the mandatory barf bags for roughly 10x-100x more population than would otherwise be with optimized motion.

Although it's very complex with lots of interacting causes, these are confirmed:
  1. There are some who gets discomfort from flicker
    You need sample-and-hold, but that adds blur
    .
  2. There are some who gets discomfort from motion blur
    You need low persistence (either via flicker/impulsing, or via ultra high framerate sample-and-hold)
    Sample-and-hold 120fps HFR still has guaranteed display motion blur
    .
  3. There are some who gets discomfort from both (sensitive to flicker, AND sensitive to motion blur)
    You need low persistence sample-and-hold via ultra high framerates (e.g. 1000fps at 1000Hz)
It can be mild discomfort or extreme discomfort. It varies from human to human. Now consider the most sensitive 0.1% of humans. Some sensitivities are so extreme, they can't even stare at most displays for long (even with maximum ergonomics settings like orange tint low-blue-light, as well as perfect brightness, proper comfortable eyeglasses prescription, as well as polarization-scattering filters, etc). By testing-by-exclusion until a cause was revealed -- there were certain cases, it was traced to display motion blur rather than flicker too. Or converse. It has happened over the old days too -- from old anecdotes of certain people being unable to stare at CRT but are okay with LCDs (as well as the converse anecdote of being unable to stare at LCDs but comfortable staring at CRTs, and was conversely solved by using a strobed LCD instead). There are people who also cant-stare-at-any-display. Display motion are imperfect simulations of real world motion, and some humans just can't ever get comfortable staring at anything at a display. Trying to five-sigma display motion comfort is a very tough thing to do.

Also, there are even cases where adding motion blur fixed some people's display discomfort too -- such as by sheer low frame rate combined with long camera exposure per frame (24fps...). It was recently noticed that the comfort curve has a valley at intermediate sample-and-hold HFR frame rates where you maximize % of display discomfort for wide-FOV displays.

Many researchers I know have actual population-sampling experience in this motion blur headaches topic matter of Blur Busters naming fame -- not so coincidentally, almost a decade ago, I chose the name "Blur Busters", based on science/research/study. ;)

Do you have any nirvana bliss modern-VR low persistence experience (i.e. Rift, Vive, Index, Quest 2 or modern comfortable-VR headsets) and have also compared it to say Zelda VR with Labo VR (large amounts of motion blur nausea from sample-and-hold Nintendo Switch) or iPhone Cardboard VR (large amounts of motion blur nausea too)? In these, do things like head turning (which forces a VR screen to pan).

You don't want to get dizzy during head turns because real world went screwy/odd (extra blur beyond human vision/brain) during head movements. The same problem also occurs for non-VR wide-FOV situations, though becomes progressively less of a problem the smaller FOV you go (less immersive situations). At 30-degrees FOV (arm's length from gaming monitor) or less (couch-far-from-average-TV), sample-and-hold HFR is far less of a problem (smaller population differences in motion sickness ratings).

Obviously there's vertigo causes (e.g. sitting on a virtual roller coaster but not feeling G-forces), but many VR apps are just perfect 6dof sync (e.g. walking around a virtual table that doesn't exist, and leaning down to inspect the bottom surface of the table), and those perfect 6dof sync'd VR apps create no nausea (on 120Hz strobed VR headsets), even for most people who get dizzy watching 3D films at the cinema. The strobe rate is high enough to be beyond most flicker sensitivity, the stroboscopic effects aren't too objectionable, the motion blur is gone, and the vertigo-solve of perfect 6dof sync (1:1 real:vr sync), etc. But a few % still get nausea from the VR flicker (even at 120Hz) but more % get nausea if we turn off the motion-blur-killing VR flicker, we get more nauseating sample-and-hold blurring (120fps HFR blur), whether for head turns (e.g. turning head left/right), or for staring at moving scenery (e.g. looking out of a window while sitting on a virtual train in VR).

Google Fu on academic search engines will still sometimes fail as this is a very new area of research but terms can include "virtual reality motion blur" as well as "virtual reality sickness" and you'll notice the due diligence that is consistent with my writings.
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MCLV
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Re: Is motion blur directly related to strobe visibility or not?

Post by MCLV » 30 Mar 2021, 02:55

Chief Blur Buster wrote:
29 Mar 2021, 16:19
To get as much five-sigma comfort as possible (least numbers of motion sick from the widest numbers of human population), you have to push the framerate really low OR really high.

The % of motion sickness cases increases with wide-FOV intermediate-framerate sample-and-hold HFR because you're getting a wide reallife FOV, but you're still getting camera motion blur or display motion blur enforced upon your human eyes.
I got you point and I don't think we are contradicting each other. When you discuss it in the context of VR you are most likely correct and I'm not challenging this part. Especially since I have literally zero personal experience with VR. My argument is that I don't agree with generalization of refresh rate requirements based on VR and other FOV filling technologies to use cases which are not that demanding.
Chief Blur Buster wrote:
28 Mar 2021, 15:05
Many film connoiseurs (including me) rather watch low frame rates (24fps), or go to 1000fps UltraHFR for sample-and-hold displays.
I believe there are use cases where this does not apply (at least not in the same strength as for VR) since:
1) Content is presented on a screen which does not fill whole FOV. Most of the content is consumed this way: PC displays, TVs, cell phones, regular cinemas (at least in my country when you exclude few first rows) do not fill your entire FOV
2) Nature of movement present in the content does not need extreme refresh rates to avoid nausea or user discomfort. There are use cases where even 60 or 120 fps could be "retina" level for that particular content and an improvement over 24 fps. Movement speeds are already controlled during professional production of movies and videos made in 24 fps so having some rules for HFR video production wouldn't be something completely new. This point clearly does not hold for VR since you can't really tell a user to move his head five times slower as usual and expect that he will still feel immersed.

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Re: Is motion blur directly related to strobe visibility or not?

Post by Chief Blur Buster » 30 Mar 2021, 03:18

MCLV wrote:
30 Mar 2021, 02:55
I got you point and I don't think we are contradicting each other. When you discuss it in the context of VR you are most likely correct and I'm not challenging this part. Especially since I have literally zero personal experience with VR. My argument is that I don't agree with generalization of refresh rate requirements based on VR and other FOV filling technologies to use cases which are not that demanding.
There's certainly a point where once screens are small enough. Both you and me are correct in that sense.

But, screens are getting bigger on average.

25 years ago we had 15" CRT-tube monitors.

Then they became 17" then 19" CRT tubes.

Then came the 21"-24" LCDs.

Now, today, many have 27" and 32" 4K gaming monitors on our desks, some using 49" ultrawides

And many worldwide are now putting putting 42", 48" and even 55" HDTVs on computer desks -- like the how popular LG CX OLEDs have become as giant gaming monitors (even if 3-4 feet view distance) -- as one example, tens of thousands of us are now using LG CX OLED 4K HDTVs as desktop monitors now, since they're the smallest "cheap" OLEDs available on the market, with 4K 120Hz G-SYNC beauty, some for as low as ~$1300 in discounted sales. TVs sell at far bigger quantities than gaming monitors, and combining one display for all media (computer+TV+streaming use) is popular in many student dorms of the 2020s, or by image-quality connosieurs, since cheap OLED is not available at smaller sizes. Many forum members will swear by a 48" desktop OLED -- like forum member sharknice -- and thousand of others elsewhere.

But viewing distances have not increased relative to the dramatic size and FOV increases. So, we're running into more and more situations where the bigger size of display created more nausea, and that's where the uncanny valley effect fixes come into play.

Simple ergonomic comfort of reduced motion blur (relative to 60fps) also needs to be considered, scrolling at 120fps is quite comfortable, but 60fps and 120fps browser scrolling can be more nauseating to some people than 15fps-30fps scrolling when we're sitting 3-4 feet away from a 40" desktop monitor. Even some people who are ultra-sensitive to motion sickness, get this already on 24"-27" 1080p monitors whereas they didn't from 15" CRTs.

You've seen thousands of motion sickness complaints (At least in North America) on the Internet from desktop monitors. Few (except Blur Busters) even merely attempt to diagnose why.

There's certainly a threshold there, but it's definitely not VR-specific.
MCLV wrote:
30 Mar 2021, 02:55
Chief Blur Buster wrote:
28 Mar 2021, 15:05
Many film connoiseurs (including me) rather watch low frame rates (24fps), or go to 1000fps UltraHFR for sample-and-hold displays.
I believe there are use cases where this does not apply (at least not in the same strength as for VR) since:
1) Content is presented on a screen which does not fill whole FOV. Most of the content is consumed this way: PC displays, TVs, cell phones, regular cinemas (at least in my country when you exclude few first rows) do not fill your entire FOV
2) Nature of movement present in the content does not need extreme refresh rates to avoid nausea or user discomfort. There are use cases where even 60 or 120 fps could be "retina" level for that particular content and an improvement over 24 fps. Movement speeds are already controlled during professional production of movies and videos made in 24 fps so having some rules for HFR video production wouldn't be something completely new. This point clearly does not hold for VR since you can't really tell a user to move his head five times slower as usual and expect that he will still feel immersed.
Depends on the VR content, as some VR content is autoplay. Much like using VR as a virtual 3D display playing out a 3D movie. Some of them even pan you, like panning a screen (simulating you sitting on a magic carpet that moves, translates, turns, etc -- watching a "real world Holdeck movie" play out).

Also, there definitely is still motion sickness from panning imagery on a 2D monitor, whether as mudane as browser scrolling (controlled by user) or movie camera panning (not controlled by user). There are many people who can't smooth scroll a browser window on a big screen, and prefers to flick pagefuls (PgUp/PgDn, or fast flickscrolls of scrollbar) to solve their scrolling motion sickness issue.

Scrolling motion sickness was observed to be somewhat reduced during low-persistence operation (pulsed) or during UltraHFR operation (e.g. 360fps 360Hz). But not everyone scrolls the same way, as they've fallen into different mudane scrolling habits.

But you are fundamentally correct: Once a display is small enough, 120fps HFR has no uncanny valley effect. But thresholds vary. For one human, it's a 24" display from 0.5 meter. For another human, it's a 55" display from 1 meter. For yet another human, it's the 7th-row-and-closer in a cinema. For yet another person, it's a 17"-or-bigger laptop at 60Hz.

When a display is sufficiently small, there's no dip (valley) in comfort when the population is averaged (even if a few get the discomfort valley for small displays). But once FOV is sufficiently big enough (even for 2D displays, not VR), the comfort dip appears at the intermediate HFR frame rates. More research is needed to determine the threshold size for the average human population (i.e. enough individual humans getting the comfort dip statistically affect the population average).

More research is definitely needed to determine the threshold where the dip (uncanny valley) statistically appears in a human population, where 24fps and 1000fps is comfortable and 120fps sample-and-hold is uncomfortable. It definitely isn't VR-specific. It even affected browser scrolling!

Even the 24fps threshold is a moving target itself -- since in some cases, 20fps or 30fps ended up becoming a bit more comfortable for some than 24fps for wide-FOV 24fps. As long as it is regular stutter to exit the immersion effect, to avoid the "smooth-motion-yet-still-blurry-motion" weird immersion motion sickness effects. (erratic stutter, e.g. fluctuating framerates, is usually worse than everything, es) The stopmotion-ness of motion, at sufficiently low frame rates, can be less uncomfortable than extra unwanted motion blur in smooth motion that covers wide-FOV.

Back in the year 1970s, they did some 60fps "HFR" experiments at the cinema -- called ShowScan -- by Douglas Trumbull. Early film HFR experiment. It was incredibly expensive, but amazing -- it only had semi-low persistence too (180-degree shutter for projector strobing between film frames = about 1/120sec projector based motion blur). While a lot of early viewers raved about it (loved it), there was a surprisingly large number of motion sick theater goers seeing the early prototypes -- with actual barf occuring. There can be multiple causes, but this shows the low-framerate-side downhill end of the uncanny valley effect right there on the spot -- nobody barfed during a 24fps film, but some people barfed during a 60fps Douglas Trumball HFR film. 8ms of persistence on film projection is still 8 inches of motion blurring during 1000 inches/sec motion on a big screen -- even when source based motion blur is zero (no blur in original camera).

There are many causes of discomfort (perception and actual fatigue). From the actual fatigue from motion blur, it is like being forced to have flawed eyes -- the human muscles tries to refocus on what looks like blurry fog, and the human eye muscles fail -- and generates eye discomfort from failing to successfully focus on the motion blur. (Remember: Some human brains/eyes autopilots in doing this beyond our control, creating a tiring effect we can't control ourselves). For any size display, there will always be those eye-trackers-during-panning. Some of us can successfully suppress our eyes' attempts to refocus unsuccessfully during display motion blur, but not all of us can.

Once a display becomes big enough, this becomes overwhelming to some people -- "I always get motion sick on those big displays, I don't like sitting close to the TV" and those "I get motion sick during gaming" kind of people Google "Video Game Motion Sickness" have tons of anecdotes. And say, your grandma, or your TV-fearing friend, or whomever, the one who loves to sit in the rear row of theater, or park a small TV something like 5-10 meters away. We *actually* study why these people get motion sick. Few bother to do.

The surprising fact is that this science all overlaps each other and we essentially "E=mc^2" and "Unifying Theory of Physics" for all this stuff in ways nobody else normally does... It spawns off to a lot of offshoots (vertigo related, FOV related, size related, causes from interactivity, causes from noninteractivity, framerate related, motion blur related, etc) all of which interact with each other to make it impossible to satisfy a population perfectly -- and ten the patterns emerge that are consistent across VR and non-VR, interactive and non-interactive.

A very clear pattern is emerging for wide-FOV because of the display-size growth problem -- a larger % of motion sickness cases were beginning to be traced to motion blur (one of the many causes), in a way significant enough to create a population-averaged uncanny valley effect. Motion sickness from interplation. Motion sickness from VR. Motion sickness from scrolling. Motion sickness from gaming. There's so many causes, but motion blur becomes a significant factor for wide-FOV high-resolution. That said, I agree the critical FOV/framerate points need to be more well researched/defined.

But, it certainly definitely isn't VR specific, because it was also traced to mudane stuff like browser scrolling and mudane stuff like human eye muscles trying to spontaneously involuntarily autofocus their eyes on a blurry image that can't ever become sharper (because of guaranteed display motion blur from sample-and-hold persistence). Maybe your eyes don't do that, but some do -- they can't help automatically try to autofocus on a blurry image. Other times it's the dizzy effect -- there are multiple causes of discomfort from display motion blur sufficiently blatant for a specific human individual -- eyestrain/motion sickness/nausea/etc.

This was a work hazard for people who panned maps all day long (satellite inspectors), of which motion blur became a problem big enough for military branches (National Geospatial-Intelligence Agency -- nga.mil) to ask manufacturers to solve it (e.g. Eizo FORIS strobe marketing to these map agencies way back in year 2013), their "240Hz" mode was 120Hz + strobe based BFI. Or even more mudane than that, Internet addicts that scroll a browser all day long, but then upgraded to a bigger monitor and discovered motion blur nausea. See, I know some of what happened behind the scenes, as I was beta-testing one of these EIZO Foris monitors way back when.

For some humans it feels natural and for some humans it feels unnatural/discomfort -- and sometimes they feel it on LCD displays as small as 17" (small % of population, statistically insignificant) -- but the uncanny valley becomes much clearer at wide-FOV high-rez (bigger % of population, statistically significant enough to show comfort valley during population averaging for intermediate sample-and-hold HFR frame rates).

By finally supersetting all the display-nausea sciences over the years (panning satellite map job work hazard, Internet scrolling addicts, Sony Motionflow Interpolation Soap-Opera-Effect nasuea, Douglas Trumball early HFR experiments, VR headsets, the progressive bigger-sizes of desktop monitors), plotting all of this into a superseat showed a very unmistakeable HFR-comfort-dip effect.

We've successfully pieced together all these components to reveal the sample-and-hold HFR comfort-dip effect, in ways nobody else has actually realized. The curve shape of the valley is not exactly known, but 24fps and 1000fps was much higher comfort than intermediate sample-and-hold HFR, even for 2D planar displays, for many people. Not everybody's comfort zone is identical, obviously. Some will have a linear comfort, some people will have a continual decline comfort (24fps and decline after), some people will be comfortable with all frame rates, etc, some have the clear dip in comfort. But averaging the population, there's a comfort dip for wide-FOV high-rez sample-and-hold HFR, even for non-VR too.

The old assumption was that motion sickness always increased for ever-increasing framerates, but that was disproven when we remapped this as a persistence problem (sample-and-hold vs low persistence). So basically high persistence motion (e.g. 50ms persistence) and low persistence motion (e.g. <1ms persistence) had less nausea than intermediate persistences (e.g. 8ms persistence), which was common to the most headachiest motions (e.g. Sony MotionFlow 120fps interpolation, cinema HFR 48fps-120fps, non-strobed VR, giant desktop screens).

And since tech finally made blurless sample-and-hold available where it wasn't possible to experimentally test this out -- the opposite-side of the uncanny valley was finally discovered, disproving that motion sickness was an "assumed" linear function of frame rate. The uphill comfort line (less blur discomfort at higher framerate), and the downhill comfort line (motion sickness at higher framerate) can superimpose (average) to create the curve where low/high persistences is more comfortable than the problematic middle persistences (e.g. sample-and-hold 48fps, 60fps and 120fps HFR blown up to IMAX sizes).

Also, intermediate-framerate HFR also gets "polarization effects" (e.g. more people raving about it, but more people feircely hating it) -- so holy wars can be started over HFR, with the smoothness lovers, versus smoothness haters. But when HFR blur was zeroed out (low-peristence 1ms or less, regardless of strobed or via ultra high frame rate), something unusual happened -- fewer cases of motion discomfort! The replication of perfect CRT 60fps effect, but with zero flicker -- having cake and eating it too. Larger displays were successfully tolerated. This was clear for VR, but was also discovered for planar 2D displays too -- even for mudane cases such as browser scrolling. We endeavoured to find out why -- and there were a quite a large number of diverse causes.

Oh and full circle back: Remember, displays are getting BIGGER on average! :D All those crazy desktop Jumbotrons, eh...

Anyway, Blur Busters is a factory of Pandora Box Openers -- we just open these display rabbit holes with glee.

In other words: Both you and me is correct. It's just that the exact FOV threshold is fuzzy. More research on that threshold is needed.

P.S. This is only 5%-10%. I can keep going on. :D

P.P.S. As many researchers scan through Area 51 for ideas, I'd like to invite more researchers to collaborate on this HFR comfort valley topic. Terminology needs to be decided, whether "HFR Uncanny Valley Effect" or "HFR Comfort Valley Effect", but this needs to be brought to better light, now more and more data has become available over the last ten years (to merge with 50+ years of subsets of comfort observations, combined with both VR and non-VR research) showing a comfort dip for intermediate sample-and-hold display frame rates, for both VR and non-VR. The necessary scientific variables (wide-FOV, high-rez) are now finally successfully confirmed, allowing more precise study/tests about how big-FOV is needed before it's population statistically-significant.
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Re: Is motion blur directly related to strobe visibility or not?

Post by Chief Blur Buster » 31 Mar 2021, 14:20

valeriy l14 wrote:
31 Mar 2021, 07:19
Listen to mark, why don't you extend the aliasing visibility test by adding the following tests there
1.Siemens star with the ability to adjust the diameter of the circle, the number of lines, the ability to make it spin clockwise or vice versa (with the ability to adjust the speed in pixels)
2.test with a checkerboard road (as in the screenshot) where the camera moves forward or in a different direction)
3. a line with a thickness of 1 pixel (or it is better to make it possible to adjust the thickness of the line with an accuracy from say 10 cm to 1 micron if possible) which moves clockwise.
4.test with words or objects that are constantly decreasing (dynamically changing the size of fonts) as in this video (17: 45-17: 59)
]

https://reobzor.ru/wp-content/uploads/2 ... 1739208.jp
https://www.youtube.com/watch?v=VrbpKHL ... l=HDTVTest
Good suggestion (long term).

I'm moving this www.testufo.com/aliasing-visibility suggestion to the TestUFO forum (correct venue for TestUFO suggestions)
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valeriy l14
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Re: Is motion blur directly related to strobe visibility or not?

Post by valeriy l14 » 09 Apr 2021, 03:49

Chief Blur Buster wrote:
31 Mar 2021, 14:20
valeriy l14 wrote:
31 Mar 2021, 07:19
Listen to mark, why don't you extend the aliasing visibility test by adding the following tests there
1.Siemens star with the ability to adjust the diameter of the circle, the number of lines, the ability to make it spin clockwise or vice versa (with the ability to adjust the speed in pixels)
2.test with a checkerboard road (as in the screenshot) where the camera moves forward or in a different direction)
3. a line with a thickness of 1 pixel (or it is better to make it possible to adjust the thickness of the line with an accuracy from say 10 cm to 1 micron if possible) which moves clockwise.
4.test with words or objects that are constantly decreasing (dynamically changing the size of fonts) as in this video (17: 45-17: 59)
]

https://reobzor.ru/wp-content/uploads/2 ... 1739208.jp
https://www.youtube.com/watch?v=VrbpKHL ... l=HDTVTest
Good suggestion (long term).

I'm moving this www.testufo.com/aliasing-visibility suggestion to the TestUFO forum (correct venue for TestUFO suggestions)
Finally, it dawned on me that if I understood correctly, a 7680x4320 display at 960 Hz will give the same level of blur as 1920 x 1080 at 240.


So for 4k ulmb should strobe with a duration of 0.5 ms and 8k with 0.25 ms. Correct me if I am wrong

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Re: Is motion blur directly related to strobe visibility or not?

Post by Chief Blur Buster » 09 Apr 2021, 11:39

valeriy l14 wrote:
09 Apr 2021, 03:49
Finally, it dawned on me that if I understood correctly, a 7680x4320 display at 960 Hz will give the same level of blur as 1920 x 1080 at 240.
From a pixels-of-blur, yes.
From a physical-inches-of-blur, no.

Confused? Here’s an explanation

Hz will determine physical distance of blur on a sample-and-hold display, while resolution will determine how many pixels per inch there is (DPI). Higher DPI (Dots Per Inch) means more pixels are blurred over the same inch.

...Although I am in a metric country, the most popular measurements for displays tend to be inches and dots-per-inches, so I will pander to the common terminology here for Popular Science Style simplicity.... Also most TVs are measured diagonally, but I will measure horizontally, to allow easier math... Here goes a simple math explanation:

If a 7680x4320 display is 60 inches wide (horizontally) = 7680 / 60 = 128 = The display is 128 pixels per inch (128 dots per inch) = 128 DPI

DPI of a Screen 60 Inches Wides
  • 1920x1080p 60” wide = 1920/60 = 32dpi
  • 3840x2160p 60” wide = 3840/60 = 64dpi
  • 7680x4320p 60” wide = 7680/60 = 128dpi
The same physical motion speed of one screen width per second (60 inches per second panning motion on a 60 inch wide display) will always have the same physical inches of motion blur, for framerate=Hz motion:

Refresh Rate Influence On 60 Inches Wide DIsplays, framerate=Hz
  • At 60 Hz, motion will move 1 inch between frames & refresh cycles.
  • At 120 Hz, motion will move 0.5 inch between frames & refresh cycles.
  • At 240 Hz, motion will move 0.25 inch between frames & refresh cycles.
  • At 480 Hz, motion will move 0.125 inch between frames & refresh cycles
  • At 960 Hz, motion will move 0.0625 inch between frames & refresh cycles.
All the above above is true regardless of resolution.

Motion blur of sample-and-hold is ALWAYS the distance a frame moved between refresh cycles. (this fundamental Sample-And-Hold Physics 101 is easy to learn for yourself by watching animations such as www.testufo.com/eyetracking#speed=-1 .... Pay attention to that animation for a few minutes until you understand sample-and-hold motion blur is always physical movement distance step).

Now, you do get more motion blur over the same number of pixels for one-screen-width-per-second.

1080p Display
  • 1920x1080p 60” wide 60 Hz = 32dpi at 1.0 inch per frame = 32 pixels of motion blur
  • 1920x1080p 60” wide 120 Hz = 32dpi at 0.5 inch per frame = 16 pixels of motion blur
  • 1920x1080p 60” wide 240 Hz = 32dpi at 0.25 inch per frame = 8 pixels of motion blur
4K Display
  • 3840x2160p 60” wide 60 Hz = 64dpi at 1.0 inch per frame = 64 pixels of motion blur
  • 3840x2160p 60” wide 120 Hz = 64dpi at 0.5 inch per frame = 32 pixels of motion blur
  • 3840x2160p 60” wide 240 Hz = 64dpi at 0.25 inch per frame = 16 pixels of motion blur
8K Display
  • 7680x4320p 60” wide 60 Hz = 128dpi at 1.0 inch per frame = 128 pixels of motion blur
  • 7680x4320p 60” wide 120 Hz = 128dpi at 0.5 inch per frame = 64 pixels of motion blur
  • 7680x4320p 60” wide 240 Hz = 128dpi at 0.25 inch per frame = 32 pixels of motion blur
So you see, although the physical thickness of motion blur is unchanged, more pixels are motionblurred over that physical distance.

This is a great example of the Vicious Cycle Effect explained in the 1000 Hz Journey Article (scroll down most of the way) — where higher resolution amplifies visibility of motion blur — simply because of the increased difference between stationary resolution (becomes sharper) and motion resolution (unchanged over physical distance). So the delta between static resolution and motion resolution increases, the higher resolutions you go.

(Remember GtG pixel response and MPRT are two different pixel response benchmarks, please see Pixel Response FAQ: GtG versus MPRT)
valeriy l14 wrote:
09 Apr 2021, 03:49
So for 4k ulmb should strobe with a duration of 0.5 ms and 8k with 0.25 ms. Correct me if I am wrong
To achieve the same pixels-of-blur as 1080p 1ms MPRT, yes. The physical distance of blur would be identical, but there will be more pixels (DPI) over that distance to blur. As explained above.
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valeriy l14
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Re: Is motion blur directly related to strobe visibility or not?

Post by valeriy l14 » 11 Apr 2021, 13:08

Chief Blur Buster wrote:
09 Apr 2021, 11:39
valeriy l14 wrote:
09 Apr 2021, 03:49
Finally, it dawned on me that if I understood correctly, a 7680x4320 display at 960 Hz will give the same level of blur as 1920 x 1080 at 240.
From a pixels-of-blur, yes.
From a physical-inches-of-blur, no.

Confused? Here’s an explanation

Hz will determine physical distance of blur on a sample-and-hold display, while resolution will determine how many pixels per inch there is (DPI). Higher DPI (Dots Per Inch) means more pixels are blurred over the same inch.

...Although I am in a metric country, the most popular measurements for displays tend to be inches and dots-per-inches, so I will pander to the common terminology here for Popular Science Style simplicity.... Also most TVs are measured diagonally, but I will measure horizontally, to allow easier math... Here goes a simple math explanation:

If a 7680x4320 display is 60 inches wide (horizontally) = 7680 / 60 = 128 = The display is 128 pixels per inch (128 dots per inch) = 128 DPI

DPI of a Screen 60 Inches Wides
  • 1920x1080p 60” wide = 1920/60 = 32dpi
  • 3840x2160p 60” wide = 3840/60 = 64dpi
  • 7680x4320p 60” wide = 7680/60 = 128dpi
The same physical motion speed of one screen width per second (60 inches per second panning motion on a 60 inch wide display) will always have the same physical inches of motion blur, for framerate=Hz motion:

Refresh Rate Influence On 60 Inches Wide DIsplays, framerate=Hz
  • At 60 Hz, motion will move 1 inch between frames & refresh cycles.
  • At 120 Hz, motion will move 0.5 inch between frames & refresh cycles.
  • At 240 Hz, motion will move 0.25 inch between frames & refresh cycles.
  • At 480 Hz, motion will move 0.125 inch between frames & refresh cycles
  • At 960 Hz, motion will move 0.0625 inch between frames & refresh cycles.
All the above above is true regardless of resolution.

Motion blur of sample-and-hold is ALWAYS the distance a frame moved between refresh cycles. (this fundamental Sample-And-Hold Physics 101 is easy to learn for yourself by watching animations such as www.testufo.com/eyetracking#speed=-1 .... Pay attention to that animation for a few minutes until you understand sample-and-hold motion blur is always physical movement distance step).

Now, you do get more motion blur over the same number of pixels for one-screen-width-per-second.

1080p Display
  • 1920x1080p 60” wide 60 Hz = 32dpi at 1.0 inch per frame = 32 pixels of motion blur
  • 1920x1080p 60” wide 120 Hz = 32dpi at 0.5 inch per frame = 16 pixels of motion blur
  • 1920x1080p 60” wide 240 Hz = 32dpi at 0.25 inch per frame = 8 pixels of motion blur
4K Display
  • 3840x2160p 60” wide 60 Hz = 64dpi at 1.0 inch per frame = 64 pixels of motion blur
  • 3840x2160p 60” wide 120 Hz = 64dpi at 0.5 inch per frame = 32 pixels of motion blur
  • 3840x2160p 60” wide 240 Hz = 64dpi at 0.25 inch per frame = 16 pixels of motion blur
8K Display
  • 7680x4320p 60” wide 60 Hz = 128dpi at 1.0 inch per frame = 128 pixels of motion blur
  • 7680x4320p 60” wide 120 Hz = 128dpi at 0.5 inch per frame = 64 pixels of motion blur
  • 7680x4320p 60” wide 240 Hz = 128dpi at 0.25 inch per frame = 32 pixels of motion blur
So you see, although the physical thickness of motion blur is unchanged, more pixels are motionblurred over that physical distance.

This is a great example of the Vicious Cycle Effect explained in the 1000 Hz Journey Article (scroll down most of the way) — where higher resolution amplifies visibility of motion blur — simply because of the increased difference between stationary resolution (becomes sharper) and motion resolution (unchanged over physical distance). So the delta between static resolution and motion resolution increases, the higher resolutions you go.

(Remember GtG pixel response and MPRT are two different pixel response benchmarks, please see Pixel Response FAQ: GtG versus MPRT)
valeriy l14 wrote:
09 Apr 2021, 03:49
So for 4k ulmb should strobe with a duration of 0.5 ms and 8k with 0.25 ms. Correct me if I am wrong
To achieve the same pixels-of-blur as 1080p 1ms MPRT, yes. The physical distance of blur would be identical, but there will be more pixels (DPI) over that distance to blur. As explained above.
Simply, I had an understanding that if we had a screen with a frequency of 1 kHz, we would get the same effect as on displays made on CRT technology, namely, the absence of the sampling and holding effect (it still seems to me that the shows that I watched on an old 21 inches lg looked perfectly smooth, like butter in a pan)


What do you think before entering the market of mass 1000 Hz monitors (2025) we will see the technology that you described, frat (I hope it will not work under dlss antialiasing or fidelity fx I hate it when the picture is lowered in resolution and then scaled)

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Re: Is motion blur directly related to strobe visibility or not?

Post by Chief Blur Buster » 12 Apr 2021, 14:03

valeriy l14 wrote:
11 Apr 2021, 13:08
Simply, I had an understanding that if we had a screen with a frequency of 1 kHz, we would get the same effect as on displays made on CRT technology, namely, the absence of the sampling and holding effect (it still seems to me that the shows that I watched on an old 21 inches lg looked perfectly smooth, like butter in a pan)
You also need a frame rate of 1 kilo-frames per second (1000fps) to also get the CRT effect on a sample-and-hold 1000Hz display.

Legacy 60fps shows would still either need to be impulse-driven (e.g. flicker) or frame rate amplified (e.g. interpolation)
valeriy l14 wrote:
11 Apr 2021, 13:08
What do you think before entering the market of mass 1000 Hz monitors (2025) we will see the technology that you described, frat (I hope it will not work under dlss antialiasing or fidelity fx I hate it when the picture is lowered in resolution and then scaled)
First high priced samples of 1000fps 1000Hz displays would likely be the 2025-2030 time window. I think the pandemic and the GPU shortage may have shifted this towards the late end of this time window.

Whether niche gaming 1000Hz displays denotes “mass production” is a good question — the need for 1000fps content (whether it be Ultra HFR Videos content, or also lower-frame-rate content going through Frame Rate Amplification Technologies (FRAT).
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  2. Please report rule violations If you see a post that violates forum rules, then report the post.
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valeriy l14
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Joined: 21 Mar 2021, 11:36

Re: Is motion blur directly related to strobe visibility or not?

Post by valeriy l14 » 19 Apr 2021, 12:20

Chief Blur Buster wrote:
12 Apr 2021, 14:03
valeriy l14 wrote:
11 Apr 2021, 13:08
Simply, I had an understanding that if we had a screen with a frequency of 1 kHz, we would get the same effect as on displays made on CRT technology, namely, the absence of the sampling and holding effect (it still seems to me that the shows that I watched on an old 21 inches lg looked perfectly smooth, like butter in a pan)
You also need a frame rate of 1 kilo-frames per second (1000fps) to also get the CRT effect on a sample-and-hold 1000Hz display.

Legacy 60fps shows would still either need to be impulse-driven (e.g. flicker) or frame rate amplified (e.g. interpolation)
valeriy l14 wrote:
11 Apr 2021, 13:08
What do you think before entering the market of mass 1000 Hz monitors (2025) we will see the technology that you described, frat (I hope it will not work under dlss antialiasing or fidelity fx I hate it when the picture is lowered in resolution and then scaled)
First high priced samples of 1000fps 1000Hz displays would likely be the 2025-2030 time window. I think the pandemic and the GPU shortage may have shifted this towards the late end of this time window.

Whether niche gaming 1000Hz displays denotes “mass production” is a good question — the need for 1000fps content (whether it be Ultra HFR Videos content, or also lower-frame-rate content going through Frame Rate Amplification Technologies (FRAT).
Okay, then you can tell me what the refresh rate of the display should be to look perfectly sharp (about 95-99% of the time) in motion for a 24 inch 2560x1440 screen (now I have 82 hz) .

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Re: Is motion blur directly related to strobe visibility or not?

Post by MCLV » 19 Apr 2021, 13:39

valeriy l14 wrote:
19 Apr 2021, 12:20
Okay, then you can tell me what the refresh rate of the display should be to look perfectly sharp (about 95-99% of the time) in motion for a 24 inch 2560x1440 screen (now I have 82 hz) .
I think Chief already answered you, it's roughly 1000 Hz on a sample-and-hold display unless you restrict movement speed. 82 Hz is good for 82 pixels per second. Anything faster produces blur (but blur at double this speed would be still quite manageable). So if you know required movement speed in pixels per second you also know required refresh rate of sample-and-hold display. This is under assumption that your eye can resolve pixels of the screen also while tracking the movement.

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