LCD Motion Artifacts 101: Introduction

Originally Posted MARCH 2013. Updated JUNE 2019

Illustrations of different motion artifacts that affect clarity of moving objects on LCD displays, using the TestUFO Ghosting Test. The UFO objects were moving horizontally at 960 pixels per second on a 60 Hz LCD, and captured using a pursuit camera.

Ghosting

pursuitcam_ghosting

  • Ghosting is a trailing motion artifact. It is caused by asymmetric pixel transitions: Transitions from between two colors can be faster in one direction than the other direction. This motion artifact appears only on trailing edges; observe the yellow dome.

Coronas / Inverse Ghosting

pursuitcam_coronas

  • Coronas are trailing artifacts caused by response time acceleration (RTC, overdrive, ASUS Trace-Free, BENQ AMA). Pixels can overshoot their final color value before bouncing back, causing bright inverse ghosting. See LCD Overdrive Artifacts FAQ for more pictures.

Motion Blur

pursuitcam_motionblur

PWM Artifacts

pursuitcam_pwm

  • PWM artifacts look like repeated images, and can affect motion fludity. PWM represents Pulse-Width Modulation, a technique that many LCD backlights use for dimming screen brightness. Motion artifacts can appear at dim brightness settings. The above photograph was taken during Brightness setting of 0%. See TFTCentral PWM.

How Were These Images Captured?

Stationary Camera: Capture of Pixel Transitions

A stationary camera is good for photographing pixel transitions statically. However, it is not a very accurate representation of perceived display motion blur and motion artifacts:

stationarycam_persistence
Example: Stationary camera photo of a moving object on a display.

Pursuit Camera: Accurate Capture of LCD Motion Artifacts

Pursuit camera are used by display manufacturers for testing (e.g. MPRT pursuit cameras). This is simply a camera that follows on-screen motion. These expensive cameras are extremely accurate at measuring motion blur and other artifacts, since they simulate the eye tracking motion of moving eyes.

However, Blur Busters has developed an inexpensive pursuit camera method which operates in conjunction with the Blur Busters UFO Motion Tests. It makes possible accurate photography of motion artifacts. The test at www.testufo.com/ghosting was used to take the pictures on this page. Blur Busters is the world’s first blog to utilize a pursuit camera for accurate capture of motion artifacts, in WYSIWYG format, as seen by the human eye.

Can All LCD Motion Artifacts Be Eliminated?

In some cases, nearly all LCD motion artifacts can be reduced by strobe or eliminated by Motion Blur Reduction settings in new gaming monitors such as ULMB or LightBoost.  These are strobe backlight technologies now built into modern gaming monitors that can be turned ON/OFF to enable motion blur reduction. As seen in high-speed video of a strobe backlight in operation, these displays produces CRT motion quality, with all perceptible motion blur completely eliminated.

More Reading About Motion Artifacts & Pixel Response


11 Comments For “LCD Motion Artifacts 101: Introduction”

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Danat
Member
Danat

Motion blur is symmetric for both trailing and leading edges. It is the blurring caused by eye tracking on continuously-displayed refreshes (sample-and-hold).

This is not pixel persistence

; but a different cause of display motion blur

This is very confusing. After reading your other articles it seems blur caused by Sample-and-hold is the same thing as blur caused by pixel persistence because in both cases the blur appears because a single frame of a moving object is displayed long enough. How can blur caused by “eye tracking on continuously-displayed refreshes” not be the same thing as blur cased by “eye tracking on frames that are displayed for the full refresh duration” (0 GtG in this example) ?

pinobot
Member
pinobot

With what shutter speed do make the stationary photograph?
I have an ‘old’ Synchmaster 2343BW and want to buy something better.
If i photograph at 1/60 i see 1 or 2 ufo’s, when i look at the screen i see 1 ufo and one shadow.

Black Octagon
Member
Black Octagon

Interesting article. I was always under the impression that motion blur, ghosting and ‘streaking’ were one and the same thing.

borf
Member
borf

The pursuit camera appears to be working well. I wasn’t aware of the PWM artifacts. Post some pics soon.

haar
Member
haar

I bought the vg278h because of your web site and the benefits of removing motion blur…

a great program for showing motion blur on your monitor (if you have a strong graphics card) is the gimark benchmark from

http://www.geeks3d.com/20121113/gputest-0-2-0-cross-platform-opengl-benchmark-furmark-lands-on-linux-and-os-x/

a strong graphics card such as the gtx680 at 1241/660o on the GiMark will produce a frame rate of 120 fps (117 to 124 on that card)

on the vg278h, lightboost on low(10%) it looks great, no motion blur.
it is also great for showing how the lightboost 10% is “the setting”… the others add a bit to a lot of “sandyness” to the picture (look Closely and you can see the difference, between off, 10%, and 20%-100%)

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