How to Test a Monitor for Ghosting
Ghosting is a faint trail behind a moving object, caused by pixels changing colour more slowly than the image moves. It is separate from motion blur, which almost every modern display produces regardless of panel speed.
What ghosting actually is
When a moving object leaves a faint trail behind it, you are seeing pixels that have not finished changing colour by the time the image has moved on. Liquid crystal takes a measurable amount of time to twist into a new position, and if that time is long relative to how fast the content is moving, the previous frame is still partly visible underneath the current one.
This is distinct from motion blur, which is a property of how displays present frames rather than a panel fault. Almost every modern screen holds each frame static for the whole refresh interval while your eye moves smoothly across it, which smears the image on your retina. A perfect panel with instant pixel transitions would still show that blur.
Setting up a fair test
Use a grey background rather than black or white. Grey-to-grey transitions are the slowest on most LCD panels, because the crystal has to settle at an intermediate position instead of swinging fully open or closed. That is also why manufacturers quote grey-to-grey figures.
Close anything demanding first. If your machine cannot keep up with the animation, you will see stutter and judder that look like a panel problem but are not. Run the frame rate test first if you are unsure.
Test at the refresh rate you actually use. Overdrive tuning is usually optimised for a panel's maximum rate, so a display that looks clean at 144Hz can ghost noticeably at 60Hz.
Reading what you see
A dark smear trailing the object is conventional ghosting — the pixel is lagging. A bright halo, either ahead of or behind the object, is inverse ghosting or overshoot: the panel's overdrive circuit has pushed the pixel past its target value and is correcting back. The two faults have opposite fixes, which is why telling them apart matters.
Pause the animation whenever you are unsure. A still object shows no trail at all, and that comparison is what your eye needs to judge whether the moving version is genuinely smeared.
What to change when you find it
Find your monitor's overdrive setting. Manufacturers name it differently — Response Time, Overdrive, TraceFree, AMA, Rampage Response — but it does the same job. The middle setting is usually the best compromise; the most aggressive setting almost always introduces overshoot.
If ghosting appears only at lower refresh rates on a variable refresh display, look for a variable overdrive option. A single overdrive tuning cannot suit every refresh rate, and some monitors adjust it dynamically.
If nothing in the menu helps, the panel is what it is. Ghosting is a physical property of the liquid crystal and no setting removes it entirely.
Test it yourself: Monitor Ghosting Test
Frequently Asked Questions
How do I know if my monitor has ghosting?
Watch a high-contrast object move across a grey background and look at its trailing edge. A faint smear following the object is ghosting. Pausing the motion gives you a clean reference — if the still object looks sharp and the moving one smears, that is the panel.
Is ghosting a defect I can return a monitor for?
Usually not on its own, because every LCD has some pixel transition time and manufacturers do not generally treat it as a fault. Severe ghosting well outside what the specification implies is worth raising, but it is a harder case than a dead pixel.
Will a faster refresh rate fix ghosting?
No. Refresh rate and pixel transition time are independent. A higher refresh rate reduces perceived sample-and-hold blur because each frame is shown for less time, but the pixels still change colour at the same speed.
What is the best overdrive setting?
Usually the middle one. The lowest setting leaves visible trailing and the highest almost always produces overshoot halos. Test each with the ghosting tool and pick the one where you can see neither.
Why does my monitor ghost more in dark scenes?
Dark grey transitions are among the slowest on many panels, and overdrive is often tuned less aggressively in that range to avoid visible overshoot on dark backgrounds. Both effects push the same way.
Sources: MDN — requestAnimationFrame() · MDN — performance.now()
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