pneu wrote:So it takes the entire duration of a frame for blur to disappear, which seems to imply that the image is in a constant state of blur?
Correct. That's the sample-and-hold effect. Doubling Hz will halve motion blur (assuming GtG does not start bottlenecking MPRT).
pneu wrote:But then how much motion resolution do I actually have?
Your motion resolution is 6.9ms or if you want a motion clarity ratio, 1000/6.9 = 144.
And yes, sample-and-hold displays have a motion resolution matching the full refresh cycle.
pneu wrote:Side note: for some reason on my system (Windows 7, Chrome) the up/down control on the MPRT pattern stops taking effect after more than 1 click until I move the mouse cursor away from the up/down control.
That's a bug in the test. The test is an experimental beta and I'll be redesigning it to be as easy to test as FPD, but I will be labelling motion resolution as MPRT instead.
This experimental test is currently not the best one to use yet for MPRT benchmarking yet (more expensive equipment is often used), but it demonstrates that it is indeed possible to measure approximate MPRT using a test pattern, and the test demonstrates that millisecond differences in MPRT are indeed human-visible. Future test patterns will need to be created for easier MPRT benchmarking, perhaps based on the old FPD test pattern but converted to MPRT numbers or MCR numbers instead.
I had to specially design the MPRT test to function with incredibly fast motion speeds far beyond FPD's abilities -- including 4000 pixels/second and faster -- including strobed at 0.5ms and 1.0ms MPRT. A test pattern as easy as FPD becomes impossible when trying to compare 0.5ms MPRT versus 1.0ms MPRT versus 2.0ms MPRT (which are human visible) and requires different special tests.
If you have an
NVIDIA ULMB monitor (nearly any 144Hz+ GSYNC monitor), here's a test that makes 0.5ms MPRT versus 1.0ms MPRT human-visible. Go to
TestUFO Panning Map Test at 3000 pixels/second. You'll be unable to read the tiny street name labels which are 6 point size text. ULMB is by default 1.0ms to 1.5ms MPRT (sometimes 2ms MPRT). Now go into the monitor's menus, and select "
ULMB Pulse Width" and lower the number to somewhere slightly 50%. That reduces the strobe flash length down to roughly 0.5ms MPRT as seen on a photodiode oscilloscope. Now you can read the street name labels! So you're probably by now, amazed that the human eye can see the difference between 0.5ms MPRT and 1.0ms MPRT. Thanks to motion blur reduction modes on modern gaming monitors capable of having adjustable MPRT (since MPRT equals strobe flash length) and NVIDIA actually added "ULMB Pulse Width" menu option upon my request after my very old
LightBoost 10% vs 50% vs 100% advocacy. Obviously, the shorter the flash length, the darker the image, so brighter monitors have been coming out to allow brighter strobing at smaller MPRT numbers. Some new 240Hz monitors can do 1ms MPRT at nearly 300 nits, and 0.5ms MPRT at well over 100 nits, thanks to voltage-boosting in their strobe backlights. Nonteheless, the point is that it's extremely difficult to create tests that are human-visible for sub-refresh-cycle MPRT numbers, unlike for easy FPD test patterns which aren't so motion-critical. eSports players can play at motionspeeds far faster than the FPD motionspeeds. And MPRT numbers are much more universal.
Currently "lines of motion resolution" is utter uselessness on Blur Busters. Why?
- The old "lines of motion resolution" tests were calibrated for TV motionspeeds instead of other kinds of motion speeds, such as videogame motionspeeds or computer scrolling motion speeds.
- FPD was designed for 60Hz. Motion resolution varies on the same display at different refresh rates
- Lines of motion resolution varies depending on motion speed.
- Pixels per frame varies depending on framerate. Maintaining the same motion speed requires bigger pixel steps at lower frame rate.
- Available framerate varies on refresh rate. The "lines of motion resolution" was invented with the assumption of 60Hz. High Hz displays give more framerate that gives you ability to increase motion resolution via reducing the sample-and-hold effect.
- Back in the NTSC days, people used stationary "lines of resolution" to measure sharpness of CRT tubes. Stationary test patterns.
- A motion test (FPD) converted the static terminology to motion terminology, "lines of motion resolution" to make it familiar to other videophiles/television engineers that were used to the old stationary "lines of resolution" tests of the older test patterns. The first invention of motion resolution was a much needed innovation in a motion test that was used in the test pattern. It was important for its time, but it is now fully obsolete. It was recyclage-of-old-terminology but is intrisinically now flawed as a display motion resolution measuring method.
- MPRT benchmarking is refresh rate independent, framerate independent, resolution independent, and motionspeed independent -- you can (fairly accurately) calculate predicted motion resolution of everything else from just one single MPRT test!
Since it was simply recycled terminology that is wholly arbitrary (since motion resolution changes depending on motion speed, and 23 pixels per frame is a very arbitrary number); the phrase "motion resolution" is an arbitrary phrase -- I've written about the outdatedness back in year 2013 in this AVSFORUM article:
Standardizing Motion Resolution: "Milliseconds of motion resolution" (MPRT) better than "Lines of motion resolution. Most manufactures now use MPRT measurements instead, and in the next 2 years I will have a much easier MPRT tests on TestUFO that is roughly as easy as FPD.
MPRT or measured motion-clarity-ratios (inverse of MPRT) is more universal, because it's easy to convert to a desired motion speed. MPRT numbers are much more universal because MPRT is motionspeed independent, unlike the old obsolete "lines of motion resolution" tests.
There are some subtle variances like how strong/faint the lines are, and differences in human vision on whether they can see the lines or not. GtG pixel response will affect this greatly, but the sample-and-hold effect will be largely dominant as long as the GtG pixel response is a tiny fraction of a refresh cycle. That's why your MPRT is darn near exactly 1/144sec -- that's correct.
pneu wrote:Can I plug known values into the above formula and solve for BEW to get the number of actual pixels of motion resolution?
Yes, MPRT numbers can easily be converted to motion resolution and vice versa if you know the motionspeed that the "lines of motion resolution" was measured at. If you don't know the motionspeed, then no, the conversion cannot happen.
TestUFO currently standardizes at 960 pixels/second because that is divisible by 60Hz, 120Hz, 240Hz and 480Hz, and is very similiar to many scrolling and common videogame speeds. And the number is so close to 1000 that as a result, it's super-easy to convert TestUFO results into MPRT number with an error margin that's within a stone's throw of expensive laboratory equipment.
Now, for alternating black-and-white lines, the same number can be converted to ANY motion speed you desire. So for single-pixel-thick alternating lines you have 2 lines so divide the inverse of MPRT by 2. The conversion formula is easy as it's a pair of pixels so you simply divide the inverse of MPRT by 2.
Converting MPRT into Lines Of Motion Resolution For 1000 Pixels/Second
(1 / (MPRT in seconds)) / 2
or
(1000 / (MPRT in milliseconds)) / 2
Translates into your motion resolution at 1000 pixels/second. Scale accordingly for different motion speeds; motion blur always scales linearly with motionspeed. Double motion speed means half motion resolution.
1ms MPRT = 500 lines of motion resolution during 1000 pixels/sec
1ms MPRT = 250 lines of motion resolution during 2000 pixels/sec
1ms MPRT = 125 lines of motion resolution during 4000 pixels/sec
10ms MPRT = 50 lines of motion resolution during 1000 pixels/sec
10ms MPRT = 25 lines of motion resolution during 2000 pixels/sec
10ms MPRT = 12.5 lines of motion resolution during 4000 pixels/sec
For your
6.9ms MPRT, the formula at 1000 pixels/sec is
(1000ms / 6.9ms) / 2 = 72 lines of motion resolution at 1000 pixels/sec
I can't remember what motionspeed and framerate the FPD test was (motion resolution will go down at faster motionspeeds and/or lower framerates on sample-and-hold displays), but if you're saying 23 pixels per frame (are you sure?) and the frame rate was 60..... Then that means if you're doing the old "lines of motion resolution" which is 23 pixels per frame at 60 frames per second = benchmark is
23ppf x 60fps = 1380 pixels/sec
So you would do the formula
(1000/1380ths) x 72 = 52 lines of motion resolution at 1380 pixels/sec under the old test pattern measurement criteria.
Now, if FPD was running at 30 frames per second instead -- then
23ppf x 30fps = 690 pixels/sec and the formula is
(1000/690) x 72 = 104 lines of motion resolution at 690 pixels/sec
Barf. What the **** does "lines of motion resolution" mean if the number varies depending on parameters?
Hell. I don't even remember what FPD motionspeed was. With MPRT numbers
I don't even need to remember the motionspeed or pixels-per-frame or whatever. MPRT becomes a universal number. Once you know MPRT of a display, the rest of the motion resolution numbers (with different variables like different framerate, different pixels per frame / different refresh rate, etc) can be estimated pretty accurately.
As you can see, MPRT conversion is universal, motionspeed independent, resolution independent, refreshrate independent, framerate independent, and that is why I feel that old "lines of motion resolution" terminology is utter obsolete trash nowadays like measuring in 15th century "Hands" measurements (and hands varied in size). MPRT is easily convertible to predicted motion resolution on the simple Blur Busters Law formula (which is the math simplification of the more complex MPRT formula)
Heck, MPRT can even be converted to "dpi of motion resolution" if you wish to invent a new method, simply by including the display's DPI in the calculation. A 300dpi display with drops to 75dpi of motion resolution
FPD was VERY useful and VERY important back in its olden days more than a decade ago,
but is obsolete with non-60Hz non-resolution-consistent monitors
I am pleased that ever since I wrote that post, more and more display manufacturers have agreed, and have begun to sometimes advertise MPRT numbers with the gaming monitor.
Regardless, there is always some subjectiveness, both with FPD tests and with MPRT tests, due to various factors like GtG curves, but the formulas begin to match human perception the closer GtG reaches 0 (resulting in more and more mathematical beautifulness). The subjectiveness means Person X sees 300 lines of motion resolution, and Person Y sees 240 lines of motion resolution. The math formulas in this post falls squarely within this arbitrary subjectiveness range, and thusly, brings a lot more mathematical beauty to subjective measurements. Neither MPRT nor FPD test manages to cover nuances such as overdrive ghosting or strobe crosstalk, but MPRT is more data-complete than old "lines of motion resolution" terminology which can vary in framerate/refreshrate/speed/resolution/etc in subsequent different motion resolution tests. So one vendor's "lines of motion resolution" test is incompatible with a different vendor's "lines of motion resolution". MPRT solves that problem as a universal constant. Although this is imperfect, this is far better and vastly superior to the obsolete "lines of motion resolution" measurement of FPD test-pattern era.
Now, in the era of GtG being a tiny fraction of a refresh cycle, MPRT matching a refresh cycle (or nearly exactly) is extremely accurate for sample-and-hold displays such as LCD, LCoS, OLED (interpolation disabled, pulsing disabled, strobing disabled, BFI disabled). MPRT only becomes sub-refresh-cycle if the refresh cycle is impulsed (strobed / phosphor / pulsed / blackframe / etc). This is also explained in my
Blur Busters Law And The Amazing Journey To Future 1000Hz Displays.
During 2019, I will be releasing some very easy MPRT motion tests that makes it much easier to quote motion resolution from MPRT numbers. And perhaps an old FPD converter tool too, for the analog-era diehards. Regardless, MPRT is The Way to go (or inverse of MPRT). I will see if I can model it after FPD, while displaying MPRT / MCR numbers, to allow easy conversion of motion resolution numbers to MPRT and vice-versa. That said, the master numeric value should always be recorded as a MPRT number (or its inverse, a measured motion clarity ratio) because amount of motion blur stays the same independently of frame rate, motion speed, resolution, refresh rate.
Nontheless, despite the obsoleteness of "Lines Of Motion Resolution", this is still an excellent idea to provide a motion resolution test that provides a good easy migration path to using MPRT (or its inverse 1/MPRT) as the proper successor motion resolution standard