Post
by Falkentyne » 04 Apr 2016, 18:21
Pixel persistence is how fast a pixel can transition between a white to black to white color state. Pixel persistence is a function of the panel itself and not of the refresh rate. Overdrive increases the voltage to "improve" pixel persistence but only certain color transitions (usually certain shades close to each other) are improved. The other transitions will be "overshot" since the amount of voltage for one transition to be improved might be less than a different color area.
At higher refresh rates, the *refresh time* of the frames are lowered, so what happens is, very often, the next frame will be ready to be displayed BEFORE the pixels transitions are completed. At low refresh rates like 60hz (16.7ms frame time), almost every color transition can be completed on a pixel color at this high lag time of 16.7ms. But at 144hz, 6.9ms...you can see very few transitions can finish.
Without backlight strobing, all that happens is overdrive overshoot ghosting, by aggressive overdrive (not having a lot of overdrive can cause streaking/extra blurriness, and having too much overdrive causes inverse ghosting).
However, blur reduction makes artifacts from pixel transitions and incomplete transitions stand out FAR more than non blur reduction. This manifests itself as Crosstalk. Because strobing removes blurring (image persistence) from the frame, what you see is the actual frame instead of blurry motion, so instead, you see part of the NEXT frame on the screen superimposed on the current frame, in the area of the screen (top to bottom refreshes-the bottom has higher input lag as it refreshes later), you see part of the next frame over the current, causing crosstalk. So at higher refresh rates, the crosstalk is worse (because the panel refresh rate time is faster).
So 144hz will have the highest crosstalk.
The reason why 120hz is tolerable is due to being able to use a Vertical total tweak, to increase the vertical blanking period. You can't do this at 144hz. 120hz without a VT tweak also has crosstalk that is too high.