darzo wrote:Makes sense. How will the pixel response time being decreased to .5ms (the other apparently more realistic figure drops as well) impact blur?
GtG response time or MPRT response time? Apples versus bananas.
Many manufacturers say one or the other, whichever number is better -- which is a little unethical. They should quote BOTH numbers for all monitors. (We might eventually begin an advocacy to begin that trend someday).
I'll answer multiple ways.
GtG response of 0.5ms inaccurately
Corona/Ghosting artifacts are much more visible than motion blur issues. A very inaccurate, asymmetric decrease of 0.5ms (some colors improving less than 0.5ms, other colors improving more than 0.5ms), will still produce visible ghosting issues, even at 480Hz and 1000Hz.
GtG response of 0.5ms accurately
If GtG is already a tiny percentage of a refresh cycle, almost no effect. 60Hz and 120Hz would not visibly improve. 240Hz may improve marginally, and 480Hz may more noticeably improve. MPRT totally dominates motion blur over GtG when GtG is less than half a refresh cycle.
What good is 0.5ms GtG for?
It's still useful. 0.5ms GtG will mainly help ultra-high refresh rates and improved strobe backlights (reduced strobe crosstalk) due to the necessity of "cramming GtG into the time period of VBI" (for advanced technical explanations, see Electronics Hacking: Creating a Strobe Backlight
as well as Advanced Strobe Crosstalk FAQ
GtG is not the same as MPRT
Having a successful 0.5ms MPRT means GtG is already far less than 0.5ms, since MPRT is refresh visibility time, and GtG lengthens that (instead of a frame instantly replaced by frame, GtG means a frame "fades" into a frame. The faster the GtG, the faster the fade. This is seen as a fade-wipe in high speed videos, like high speed video of LightBoost
-- which also shows an LCD running in non-LightBoost operation too as well. You can have instant (0ms) pixel response but 0.5ms MPRT -- that simply means each individual frames were effectively visible for 0.5ms. Either achieved via strobing (0.5ms flashes of each refresh cycles). OR if you filled all black periods with 0.5ms frames, that requires 2000 frames per second (at 2000Hz) to avoid the need of any blackness. Same blur either way, MPRT 0.5ms is 0.5ms of motion blur, whether it's strobed (easy at lower Hz) or unstrobed (needs insane Hz).
MPRT cannot be less than GtG on sample-and-hold without strobing
As a rule of thumb, slow GtG tends to lead to at least equally big MPRTs. If you want 0.5ms MPRT, that means your GtG needs to be far less than 0.5ms. During the 1990s, we had very slow 33ms LCDs which motion blurred over multiple refresh cycles (called "streaking") since 33ms is more than one 60Hz refresh cycle long. More motion blur = more MPRT.
However, MPRT can be less than GtG with strobing
That's because MPRT is the visible part, while GtG can occur in the dark part. This is commonly done with ULMB. 120Hz means an 8.3ms refresh cycle. (1/120sec = 8.3ms). You only need 1ms to make the refresh cycle visible. That means you have 7.3ms of total darkness to let GtG complete merrily unseen by human eyes. (Realistically, you have less time than that, due to scanout latencies, but you have way more than 1ms of darkness to do GtG unseen by eyes). So you can have 2ms GtG and 1ms MPRT with a strobed ULMB display. Simply because GtG occurs during the dark part of refresh cycle and MPRT is the visible part of the refres cycle.
.... For simplicity-of-explanation, I'm omitting scanout latency (the finite amount of time to refresh a screen top-to-bottom, since all pixels don't begin their GtG cycle simultaneously -- so need to cram GtG into a large VBI), but that's the gist -- put the GtG in the dark cycle and MPRT is the visible part of refresh cycle -- allowing MPRT to be smaller than GtG when a strobe backlight is used.
GtG can be less than MPRT
GtG stops becoming the motion blur limiting factor when GtG is a tiny fraction of a refresh cycle. MPRT becomes the dominant factor for motion blur.
0.5ms GtG means better 240Hz, 480Hz, 1000Hz, less ghosting, and less strobe crosstalk.
0.5ms MPRT means 0.5 pixel motion blur during 1000 pixels/sec motion.
Today, 0.5ms MPRT already exists with ULMB
BenQ strobing (With Strobe Utility) and ULMB displays (With ULMB Pulse Width) are capable of 0.25ms MPRT already today. MPRT is strobe length. The problem is that ultra-short MPRTs is usually very dim.
The human eye can tell apart 0.5ms MPRT and 1.0ms MPRT during ultra-fast motion tests with extremely fine details. You can see it for yourself with ULMB.
1. Look at TestUFO Panning Map Test
at 3000 pixels/sec, you can easily see the effects of ULMB Pulse Width adjustments.
2. Adjust ULMB between PW100%, 50% and 25% which roughly corresponds to 1.5ms-2ms MPRT, ~1ms MPRT, and ~0.5ms MPRT. It varies from ULMB monitor to monitor. TFTCentral often has the pulse widths, and pulse widths typically corresponds to MPRT. Turn off your lights and close all your drapes, as low "ULMB Pulse Widths" will be very dark on most monitors. However, some newer ULMB monitors manage to pull off 0.5ms MPRT with approximately ~100cd/m2
3. Result: Google Map speeding at 3000 pixels/second with MPRT adjustable via ULMB Pulse Width
2ms MPRT = 6 pixels motion blur (map labels unreadable)
1ms MPRT = 3 pixels motion blur (map labels slightly fuzzy)
0.5ms MPRT = 1.5 pixels motion blur (map labels very clear)
To chieve the same numbers WITHOUT
2ms MPRT = 500fps@500Hz needed to avoid strobing (fill all black periods with 2ms frames)
1ms MPRT = 1000fps@1000Hz needed to avoid strobing (fill all black periods with 1ms frames)
0.5ms MPRT = 2000fps@2000Hz needed to avoid strobing (fill all black periods with 0.5ms frames)
So as you can see, strobeless ULMB requires Hertz insanity. To the surprise of many people. But the motion blur mathematics is beautifully simple (Blur Busters Law).