Black Octagon wrote:As Mark explained it to me, your screen's pixel transition time - the real one, not the manufacturer's declared pixel response time - needs to be at least as fast as 50% of the display refresh time in order for pixel persistence to no longer be a real issue.
I didn't say "real issue" --
It just
ceases to be the dominant problem for motion blur
So this is what I actually meant: "
Once the pixel transition is significantly than a refresh cycle, GtG ceases to be the motion blur limiting factor".
Note: persistence (pixel static state) is different from transitions (pixel movement).
Pixel _persistence_ is still an issue even at 0ms instant pixel transitions.
Even 2ms persistence still has noticeably more motion blur than 1ms persistence.
However, 2ms GtG does not have noticeably more motion blur than 1ms GtG, since persistence is the dominant factor.
Black Octagon wrote:Unlike gaming TNs, IPS panels cannot do pixel transitions faster than 4ms, so at 120hz there is done added motion blur.
False.
I
CAN see motion blur differences between 0.5ms, 1.0ms, 2.0ms, 3.0ms, and 4.0ms persistence.
I
CAN'T see motion blur differences between 0.5ms, 1.0ms, 2.0ms, 3.0ms, and 4.0ms GtG.
Persistence is more important than GtG in motion blur.
GtG just ceases to be the motion blur limiting factor when it's less than 50% of a refresh cycle.
The baton of the dominant motion blur limiting factor transfers over to persistence, which is bottlenecked at the frame visibility length. e.g. Most 2ms LCDs have 16.7ms of persistence. (Good demo of persistence:
http://www.testufo.com/eyetracking ...)
Mathematically, 1ms equals 1 pixel of motion blurring during 1000 pixels/second (e.g.
http://www.testufo.com/photo ).
0.5ms persistence = 1 pixel of motion blur during 2000 pixels/second motion
1ms persistence = 1 pixel of motion blur during 1000 pixels/second motion
2ms persistence = 1 pixel of motion blur during 500 pixels/second motion
4ms persistence = 1 pixel of motion blur during 250 pixels/second motion
or conversely,
0.5ms persistence = 0.5 pixel of motion blur during 1000 pixels/second motion
1ms persistence = 1 pixel of motion blur during 1000 pixels/second motion
2ms persistence = 2 pixel of motion blur during 1000 pixels/second motion
4ms persistence = 4 pixel of motion blur during 1000 pixels/second motion
However, manufacturers rate in GtG (pixel transition speed), but not in persistence (pixel visiblilty time during a frame).
There's only two effective ways to lower persistence:
1. Shorten pixel visibility by strobing (black frame insertion, strobing, etc)
2. Shorten pixel visibility by increasing number of frames (120fps@120Hz, 240fps@240Hz)
As you track moving objects with your eyes on a display, your eyes are in a different position at the beginning of a visible refresh than at the end of the visible refresh. This is because your eyes are continuously moving, while the frames themselves stay static during a refresh cycle. Tracking moving objects on a 60Hz flickerfree display, is metaphorically equivalent to trying to take a camera photograph with 1/60sec shutter while panning the camera: Blurry photograph. The longer time a static pixel is visible for, the more motion blurring will occur (Example:
http://www.testufo.com/eyetracking ). Now if you flash the backlight for only 1ms (e.g. LightBoost 10%), the backlight is metaphorically equivalent to a 1/1000sec camera shutter -- keeping things sharp during fast motion.
So, again, motion blur is still a problem even at 2ms persistence, 3ms persistence, 4ms persistence. It's just that the manufacturers rate using the transition formula (grey-to-grey pixel movement) rather than the persistence formula (pixel static/visible state == sample-and-hold effect == persistence), and motion blur is directly proportional to persistence.
This is a simplified example of what was happening over the last 10 years:
33ms GtG LCDs -- about 33ms+ of motion blur at 60Hz (often worse)
25ms GtG LCDs -- about 25ms+ of motion blur at 60Hz (often worse)
16ms GtG LCDs -- about 16.7ms+ of motion blur at 60Hz (often worse)
8ms GtG LCDs -- about 16.7ms+ of motion blur at 60Hz (often slightly worse)
5ms GtG LCDs -- about 16.7ms of motion blur at 60Hz (very accurately 16.7ms of motion blur)
4ms GtG LCDs -- about 16.7ms of motion blur at 60Hz (very accurately 16.7ms of motion blur)
2ms GtG LCDs -- about 16.7ms of motion blur at 60Hz (very accurately 16.7ms of motion blur)
1ms GtG LCDs -- about 16.7ms of motion blur at 60Hz (very accurately 16.7ms of motion blur)
(1/60 second equals 16.7ms, and that's 16.7 pixels of motion blur during 1000 pixels/second motion).
Motion blur is bottlenecked by persistence once GtG dips below half a frame cycle. Meaning, there is a motion blur problem even with 1ms LCDs, because of the persistence problem (sample-and-hold effect), as demonstrated by the animation at
http://www.testufo.com/eyetracking