"LCDs tend to be bang-on, bang-off with sudden image changes...."
I think that's a little wrong...most LCD's have a backlight that is always on...and pixels that "gradually" change as the "liquid crystal" rotates from one position to another. The motion blur, I think, is because the pixel is always showing light through it, but if it can't change fast enough (ie: a slow pixel response), then the screen will still show some remnant of previous frames.
If HDTV is 60Hz, and a pixel response time is 16ms, then, for a fast moving/changing scene, the pixels just barely get to the right position before the next frame has to start....so things will look blurry if there's light shining through that "wrong" pixel most of the time.
Adding more frames helps some, as it makes it so there's less change from one frame to the next (interpolated) frame.
Fast pixel responses also help some...but with, say, a 1ms response time, now your LCD basically becomes a flip-book with a long duration of constant picture for each frame.
I've read that the best way to help is to flicker the backlight at 60 (or 120 or whatever) Hz, so light only comes through when the pixels are "right". That basically gets closer to the way a plasma/CRT is (with pixels really only being "on" for a short amount of time). The problem, though, is that the screen ends up looking dimmer (since the backlight is off most of the time), and a dim screen looks bad on a show-room floor. I'm guessing that standard fluorescent back lights can only get so bright....but maybe in the future, with bright LED backlights, screen brightness won't be sacrificed, and this idea will end up being used more....
Reader Comments (Page 1 of 1)
EQC @ Jun 1st 2008 5:41PM
"LCDs tend to be bang-on, bang-off with sudden image changes...."
I think that's a little wrong...most LCD's have a backlight that is always on...and pixels that "gradually" change as the "liquid crystal" rotates from one position to another. The motion blur, I think, is because the pixel is always showing light through it, but if it can't change fast enough (ie: a slow pixel response), then the screen will still show some remnant of previous frames.
If HDTV is 60Hz, and a pixel response time is 16ms, then, for a fast moving/changing scene, the pixels just barely get to the right position before the next frame has to start....so things will look blurry if there's light shining through that "wrong" pixel most of the time.
Adding more frames helps some, as it makes it so there's less change from one frame to the next (interpolated) frame.
Fast pixel responses also help some...but with, say, a 1ms response time, now your LCD basically becomes a flip-book with a long duration of constant picture for each frame.
I've read that the best way to help is to flicker the backlight at 60 (or 120 or whatever) Hz, so light only comes through when the pixels are "right". That basically gets closer to the way a plasma/CRT is (with pixels really only being "on" for a short amount of time). The problem, though, is that the screen ends up looking dimmer (since the backlight is off most of the time), and a dim screen looks bad on a show-room floor. I'm guessing that standard fluorescent back lights can only get so bright....but maybe in the future, with bright LED backlights, screen brightness won't be sacrificed, and this idea will end up being used more....