UK What monitor ghosting looks like
Monitor ghosting is a smeared or doubled trail that follows anything moving across an LCD screen: a scrolling window, a mouse pointer, a moving conveyor on a camera feed or a fast-changing trend line. The trail fades within a fraction of a second and disappears when the image stops moving.
It happens because an LCD pixel cannot change colour instantly. The liquid crystals have to physically rotate to let more or less light through. If that takes longer than one frame, the pixel is still part-way between the old and new colours when the next frame arrives, and the eye sees traces of where the object was.
Ghosting is different from image retention or burn-in, where a static image stays faintly visible after it has gone. Ghosting only affects motion and leaves no lasting mark.
What causes monitor ghosting
Several factors, often together, make a screen ghost.
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Slow pixel response. The panel’s response time is long compared with the frame time. At 60 Hz each frame lasts about 16.7 ms, so a panel that takes longer than that to settle will smear.
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Panel type. VA panels are often slow when changing between dark shades, which shows as dark smearing. IPS panels are usually more even across transitions.
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Overdrive set wrong. Too little overdrive leaves trails; too much causes bright halos, called inverse ghosting or overshoot.
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Cold temperatures. Liquid crystal becomes more viscous as it cools, so response slows sharply below freezing.
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Analogue signal problems. On VGA connections, long or poor-quality cables cause reflections that show as a faint double image beside text and edges, even on a still picture.
Response time and overdrive explained
Response time is how long a pixel takes to change from one shade to another. It is usually quoted as grey-to-grey (GtG), the time to move between two mid-grey levels. Industrial panel datasheets often quote rise and fall times instead, black to white and back, and the two figures are not directly comparable.
Overdrive briefly applies a higher voltage to the crystal to push it towards the new shade faster, then drops back. Set correctly, it cuts ghosting without side effects. Set too high, the pixel overshoots its target and a light halo appears behind moving objects.
| Term | What it means | What to look for |
|---|---|---|
| GtG response time | Time for a pixel to move between two grey levels | Lower is faster; around 5 ms or less suits video and moving graphics |
| Rise and fall time | Black-to-white plus white-to-black time, common on industrial datasheets | Often quoted as a combined figure of around 10 to 30 ms |
| MPRT | How long each frame stays visible, which the eye reads as blur | Lower at higher refresh rates or with backlight strobing |
| Overdrive | Extra drive voltage that speeds up pixel changes | Use the middle setting first; too high causes inverse ghosting |
| Refresh rate | How many new frames the screen shows each second | 60 Hz is standard; higher rates only help if the panel keeps up |
| Input lag | Delay between the signal arriving and the image changing | A separate issue from ghosting; matters for fast interaction |
Manufacturers measure response time in different ways, so a lower number on one datasheet does not always mean less ghosting than a higher number on another.
Ghosting in cold and outdoor installations
Temperature is the cause most often missed on site. A monitor that looks perfect in the office can smear badly in an unheated warehouse, a vehicle cab on a winter morning or an outdoor cabinet, because response time can become several times slower below about 0 °C. The panel is not damaged and recovers as it warms, but trend displays and camera feeds can be hard to read until it does.
For cold sites, check the panel’s rated operating temperature, not just the electronics. Some displays for outdoor and vehicle use add a panel heater that warms the LCD before and during operation, and some of our rugged monitors and sunlight readable models include one. Keeping the enclosure above freezing has the same effect. Our FAQ on the industrial temperature range explains how operating ranges are specified.
How to fix monitor ghosting
Most ghosting can be cured or reduced in a few steps, starting with the free settings before any hardware change.
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Confirm it. Run a motion test, such as the moving-object patterns on TestUFO, to check that what you see is ghosting rather than a signal fault.
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Adjust overdrive. Try each setting in the monitor menu, often labelled Response Time, OD or Trace Free, and keep the one with neither trails nor halos.
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Match the signal. Set the computer to the panel’s native resolution and refresh rate.
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Go digital. Replace VGA with HDMI, DisplayPort or DVI, or shorten and upgrade the cable.
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Warm it up. Let a cold display reach temperature, or choose a model rated or heated for the site.
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Change the panel. If ghosting persists, choose a panel with a faster response time for motion-heavy work.
Quick answers on monitor ghosting
Monitor ghosting: common questions
What is ghosting on a monitor?
Trails behind moving images. Pixels change colour too slowly for the moving picture, so faint copies of earlier frames stay visible behind moving objects.
Is monitor ghosting permanent?
No. Ghosting only appears while the image is moving and does not damage the screen. Image that stays on a still screen is burn-in or image retention, a different problem.
What is overdrive on a monitor?
A setting that speeds up pixels. It drives the liquid crystals harder for a moment so they reach the new shade faster. The best setting is usually the middle one.
What is a good response time for a monitor?
Around 5 ms or less GtG. That is fast enough for video and moving graphics at 60 Hz. Static HMIs and data screens can work well with slower panels.
Can a cable cause ghosting?
Yes, on analogue VGA. Long or poor VGA cables can produce a faint double image. Digital links such as HDMI and DisplayPort do not ghost this way.
We supply industrial monitors with panels rated for the site’s temperature range and the content they will show, configured and tested before they ship as standard. Tell us where the screen will be installed and what it will display, and we will recommend a suitable model.