Monitor Ghosting: Response Time and Overdrive Explained

What monitor ghosting is

Ghosting is a faint trail that follows moving objects on a screen, most visible behind a mouse cursor, scrolling text, or a player turning in a game. It happens because pixels cannot change color instantly. RTINGS defines response time as the time pixels take to switch from one color to another, and notes that slow response causes blur behind fast-moving objects.

Ghosting only exists while things move. A faint copy of an old image that stays on a still screen is something else, image retention or burn in, covered in image retention vs burn in.

Ghosting and its look-alikes

How to test your monitor for ghosting, step by step

1. Check the refresh rate first. Open the refresh rate test. A 144 Hz monitor stuck at 60 Hz blurs far more than it should, and no overdrive setting fixes that. The refresh rate guide covers the fix.
2. Open the motion test and go full screen on the monitor you are testing.
3. Set the speed to 960 pixels per second and follow one moving object with your eyes. Do not stare at a fixed point: motion blur is what your eyes see while tracking.
4. Look behind and around the object. A smeared trail is ghosting; a bright or colored edge is overshoot; a sharp double image is strobe crosstalk.
5. Switch to the several backgrounds mode. Trails often look different on each shade, and dark to mid gray transitions are the slowest on many panels.
6. Change the monitor's overdrive setting one level at a time and repeat. Keep the level with the shortest trail and no visible halo.
7. Repeat at 60 Hz or with VRR on if you play games that run below your maximum frame rate, since overdrive behavior can change with the refresh rate.

Response time explained: GtG, MPRT and why 1 ms rarely means 1 ms

Gray to gray (GtG)

GtG is the time a pixel takes to move from one shade of gray to another. RTINGS measures a grid of transitions between 0%, 20%, 40%, 60%, 80% and 100% gray and reports two kinds of numbers:

• Rise and fall time: from 10% to 90% of the way through the transition, which leaves out the slow start and finish.
• Total response time: until the transition is complete (with a 2% allowance for noise). This is closer to what your eyes see as a trail.

RTINGS also reports overshoot error, the percentage by which a pixel passes its target. Their example: aiming for 80% gray and hitting 85% is an overshoot of 6.25% of the target, and one monitor's strongest overdrive setting overshot a 20% target by 236%, which showed up as inverse ghosting.

MPRT

Motion Picture Response Time is a blur measure tied to how long each image stays on screen while your eyes follow motion. Backlight strobing shortens exactly that, which is why backlight strobing improves it so much, and why some brands name their strobing mode after it (MSI's setting is called Moving Picture Response Time, according to RTINGS).

Why spec sheet numbers mislead

• A quick GtG figure can be achieved with aggressive overdrive that overshoots badly. VESA states that time-based metrics such as MPRT cannot account for excessive overshoot and undershoot, which create artifacts.
• Numbers from different brands are measured in different ways, so they are not comparable.

Better signals to look for

• VESA ClearMR: a certification that grades motion blur by the ratio of clear to blurry pixels, in tiers from ClearMR 3000 upward (ClearMR 7000 means 65 to 75 times more clear pixels than blurry ones). It limits overshoot tricks during testing.
• VESA AdaptiveSync Display: its tests include gray to gray response time with overshoot and undershoot limits, run in the factory default settings.
• Independent measurements: RTINGS now scores motion with Cumulative Absolute Deviation (CAD), which combines response time and overshoot in one number.

What causes ghosting

Panel type

RTINGS summarizes it: OLED has near instantaneous response and the best motion handling, while VA panels are typically slower in dark transitions than IPS and TN, which leads to black smearing. Some VA monitors push overdrive harder to hide it, at the cost of overshoot in bright scenes.

Overdrive set wrong

Overdrive (usually called Overdrive or Response Time in the monitor menu) briefly drives pixels harder than needed so they arrive sooner. Too low leaves trails; too high overshoots. RTINGS notes that the highest setting is often not the best one and picks the setting that balances speed and overshoot.

Refresh rate and frame rate

Response behavior changes with the refresh rate, which is why RTINGS measures at the maximum rate, 120 Hz and 60 Hz separately. Monitors with a native G-SYNC processor can adjust overdrive to the frame rate to keep motion consistent. On other monitors, check lower refresh rates too, because a setting that looks clean at the maximum rate may not look the same when VRR lowers it. Some monitors lock the overdrive setting when VRR is on.

Persistence

Even a perfect panel blurs moving objects if each image stays on screen for a long time. RTINGS explains that the longer a frame is kept on screen, the blurrier moving objects look, so a 60 fps game on a fast monitor still blurs more than the same game at 144 fps.

How to fix monitor ghosting

You cannot change a panel's built-in response time, but these settings change how motion looks. Test each one with the motion test.

1. Run the highest refresh rate your monitor supports and make sure the computer is set to it. RTINGS recommends the highest rate your monitor and graphics card can reach.
2. Tune overdrive. Start at the middle setting, then move one step at a time. Stop at the level with the shortest trail and no bright halo. Check dark backgrounds too.
3. Raise your frame rate toward the refresh rate if you can, since each frame is held for less time.
4. Try backlight strobing if your monitor has it (table below). It reduces persistence blur a lot, with trade offs.
5. Reset the picture mode if a preset changed overdrive or locked it. RTINGS suggests going back to the default values if a setting makes the picture worse.

Backlight strobing: names and trade offs

Backlight strobing (black frame insertion on OLED) flashes the image instead of holding it, which cuts persistence blur. NVIDIA's ULMB 2 page shows the idea: the original ULMB kept the backlight off 75% of the time, and effective motion clarity equals refresh rate times one over the duty cycle, so a strobed 120 Hz screen at a 25% duty cycle looks about as clear as a 480 Hz screen without strobing.

• Dimmer picture. The light is off part of the time, and many monitors lock brightness in this mode.
• Flicker, which RTINGS notes bothers some users.
• Often no VRR at the same time. RTINGS notes many monitors do not allow both; NVIDIA's instructions for ULMB 2 start by turning G-SYNC off.
• Double images (crosstalk) if strobe timing and pixel transitions do not line up; some monitors let you adjust pulse width or phase to reduce it.

What does not fix ghosting

• New cables or reinstalling drivers. Ghosting comes from how the panel's pixels change, not from the signal.
• Pixel fixing tools. Those target stuck pixels, not response time.
• Maximum overdrive on its own. It usually trades trails for halos.

Is ghosting a defect or covered by warranty?

Some ghosting is normal on every LCD, and how much is a property of the panel model rather than a fault in your unit. It is worth taking up with the seller or manufacturer when:

• Your monitor looks clearly worse in the motion test than independent reviews of the same model at the same refresh rate and overdrive setting.
• Trails appear only in one area of the screen, or suddenly got much worse.
• The overdrive or strobing setting advertised for the model is missing or has no effect; a firmware update from the maker may be available.

Warranty and return terms differ between manufacturers and sellers, so check how yours treat motion performance. Read the terms that came with your monitor, and if you are within a store's return period, that is usually the simplest route when a model simply does not suit you.

Choosing a monitor with less ghosting

• OLED for the cleanest motion, since response is near instant. Persistence blur still depends on refresh rate.
• Fast IPS for a balance of speed and price; check that reviews show little overshoot at the recommended overdrive.
• VA if contrast matters most, but look at dark transition results to avoid black smearing.
• Higher refresh rate, because it cuts persistence blur. See 60 Hz vs 144 Hz.
• Measured results over spec sheets: independent reviews, VESA ClearMR tiers and VESA AdaptiveSync certification tell you more than a 1 ms claim.