These photos compare motion blur between 60Hz versus 120Hz versus LightBoost strobe backlight. All images below are captured from the same computer monitor. These demonstrates differences in perceived motion blur caused by the sample-and-hold effect.
These UFO objects were moving horizontally at 960 pixels per second, at a frame rate matching refresh rate, on an ASUS VG278H LCD. These close-up pictures were taken using a pursuit camera at 1/30sec exposure (exposing multiple refreshes into same photo).
120 Hz Refresh rate:
Each refresh is displayed continuously for a full 1/120 second (8.3ms)
This creates 50% less motion blur. This includes regular and overclocked 120Hz.
This results in approximately 8 pixels of motion blur during 960 pixels/sec motion.
120 Hz LightBoost: CRT quality motion
The backlight is strobed briefly, once per refresh, eliminating sample-and-hold.
With LightBoost, 120fps @ 120Hz has 85% to 92% less motion blur than 60Hz.
This results in just 1 to 2 pixels of motion blur during 960 pixels/sec motion.
At 120fps@120Hz, a 1/30second camera exposure captures 4 refreshes. All 4 refreshes are stacked on each other, because the pursuit camera is moving in sync with the 120fps@120Hz moving object at a 1/30second camera exposure.
The brief backlight flash prevents tracking-based motion blur. There is extremely little leftover ghosting caused by pixel transitions (virtually invisible to the human eye), since nearly all (>99%+) pixel transitions, including overdrive artifacts, are now kept unseen by the human eye, while the backlight is turned off between refreshes. See high speed video.
The backlight strobe flash length is measured to be 1.5ms by TFT Central. This is more than 90% shorter than a 60Hz refresh (16.7ms). The LightBoost 10% setting (via monitor OSD menu) uses 1.4ms strobe flashes (as measured by our oscilloscope at Blur Busters), while the LightBoost 100% setting uses 2.4ms strobe flashes. This is still greatly shorter than even a 120Hz refresh (8.3ms)! As a result, motion clarity on a LightBoost monitor is comparable to a CRT display.
This graph illustrates the difference in motion blur between different refresh rates, including LightBoost and non-LightBoost. Even 100 Hz LightBoost has less motion blur than 144Hz non-LightBoost. In the best case scenario, 1.4ms is 92% less than 16.7ms — and this also accurately corresponds to the amount of motion blur perceived by human vision, and pursuit camera photography.
1ms of motion blur = 1 pixel of motion blur during 1000 pixels/sec, from the sample-and-hold effect, as demonstrated & explained at TestUFO at www.testufo.com/eyetracking.
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:
Pursuit Camera: Accurate Capture of LCD Motion Artifacts
Pursuit camera are used by display manufacturers for testing (e.g. MotionMaster, and other 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.
Blur Busters has developed an inexpensive pursuit camera method which operates in conjunction with the Blur Busters Motion Test (www.testufo.com), and also makes possible accurate photography of common LCD motion blur artifacts. The Ghosting Motion Test was used to take the pictures on this page, with the VG278H monitor adjusted to lower contrast (65%).
Blur Busters Blog is the world’s first blog to utilize a pursuit camera for the accurate capture of motion artifacts, in WYSIWYG format, as seen by the human eye.
The comparison graph was created from motion tests & oscilloscope measurements, including PixPerAn and Blur Busters Motion Tests, and cross-checked with TFTCentral oscilloscope tests (for 120Hz LightBoost = 100%). Accuracy +/- 0.1ms, assumes TN panel technology with optimized RTC, motion tests done with VSYNC ON with frame rate matching refresh rate.