DeviTestResponse time and ghosting explained
Ghosting is the faint trail you see behind moving objects. It comes from how fast pixels change color — and from how long each frame stays on screen.
GtG: how fast pixels change
Gray-to-gray (GtG) response time is how long a pixel takes to switch from one shade to another. Slow transitions leave a blurry trail behind moving objects. VA panels are often slowest in dark transitions, which shows as dark smearing.
MPRT: how long each frame is visible
Even with instant pixels, your eyes see blur because each frame is held on screen until the next one — this is called sample-and-hold blur. MPRT measures this. Higher refresh rates reduce it, which is why 144Hz looks sharper in motion than 60Hz.
Overdrive and overshoot
Monitors use overdrive to push pixels faster. Too much of it causes overshoot: a bright or dark halo (inverse ghosting) behind objects. If you see a halo, try a lower overdrive setting in the monitor menu.
What BFI does
Black Frame Insertion shows a black frame between images, so each image is visible for less time. Motion looks sharper, but the screen gets dimmer and may flicker. It works best at high refresh rates.
Checking it yourself
The ghosting test moves squares across dark, gray and white backgrounds at three speeds. Compare the trail length between settings or screens. A browser can't measure response time in milliseconds — that needs a camera or light sensor — but it's very effective for visual comparison.