Monitor Ghosting Test
Moving blocks at a speed you control. A smear behind an object is ghosting; a bright halo in front of it is overdrive overshoot.
Follow one block with your eyes, then try holding your gaze still and letting it pass — the two reveal different faults.
Trailing or haloing?
These are opposite problems and the fix goes in opposite directions, so telling them apart is the whole point of the test.
- Trailing / smearing — a faint copy dragging behind the block. The pixels are switching too slowly. Increase overdrive.
- Overshoot / inverse ghosting — a bright or oddly coloured halo in front of the block. Overdrive is pushing too hard and the pixels overshoot before settling. Decrease it.
- Black smear — dark-to-light transitions lag noticeably, most obvious on the black background. Characteristic of VA panels; not a defect.
Finding the right overdrive setting
- Set the speed to around 960 px/s — fast enough to expose problems, slow enough to see them.
- Open your monitor's on-screen menu and find Overdrive (it may be called Response Time, TraceFree, AMA, or Rampage Response).
- Start at the lowest setting and step up one level at a time, watching this page after each change.
- Stop at the highest level that shows no bright halo. On most monitors that is the middle option; the maximum setting is usually overdriven on purpose to win specification comparisons.
Two ways to look, two different faults
Track a block with your eyes and you are testing persistence blur — the smearing caused by the image holding still on screen while your eye moves. Hold your gaze fixed and let a block pass through it and you are testing pixel response — actual ghosting. Sample-and-hold displays, which is nearly all of them, always show some persistence blur regardless of how fast the pixels are.
What this test cannot tell you
It cannot give you a millisecond response-time figure — that needs an oscilloscope and a photodiode, not a browser. What it does give you is the thing that actually matters: whether you can see the artefact at speeds you actually use, and which direction to move your overdrive setting.
Motion problems are often really refresh-rate problems, so it is worth confirming the panel is running at its rated speed with the refresh rate test. If the trouble is colour rather than motion, try the screen colour test.
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Frequently asked questions
What is monitor ghosting?
A faint trail left behind a moving object. It happens when pixels cannot change colour fast enough to keep up with the image, so the previous frame is still partly visible in the next one. It is most obvious with a light object on a dark background, or vice versa.
How do I test my monitor for ghosting?
Watch the moving blocks above at a speed you would actually encounter — around 600 to 960 pixels per second is realistic for gaming. Look at the trailing edge for a smear, and the leading edge for a bright halo. Raise the speed until you can see it, then compare against your monitor's overdrive settings.
What is overshoot, and how is it different?
Overdrive pushes pixels harder so they switch faster. Too much and they overshoot the target colour before settling, which appears as a bright or inverted halo in FRONT of the moving object rather than a trail behind it. Trailing means too little overdrive; haloing means too much.
How do I reduce ghosting?
Find the overdrive setting in your monitor's menu — it is usually called Overdrive, Response Time, TraceFree, AMA or Rampage Response. Step it up one level at a time and retest here. Stop at the highest setting that does not produce a bright halo. The middle option is correct on most monitors.
Does a higher refresh rate reduce ghosting?
Indirectly. A higher refresh rate shortens the time each frame is on screen, so any given trail is visible for less time. But the underlying pixel response is a property of the panel — a slow 144 Hz panel can ghost more than a fast 60 Hz one. Check your actual refresh rate separately.
Is some ghosting normal?
Yes. Every LCD has a measurable response time, and VA panels are notably slower on dark transitions — the "black smear" people report is normal VA behaviour, not a fault. TN and modern IPS are faster. OLED is effectively instant.