Ghosting Test

What Is Monitor Ghosting and How Does the Ghosting & Overdrive Test Expose It?

Ghosting vs Motion Blur: Understanding the Difference

Ghosting is a visual artifact caused by slow pixel response — specifically, the failure of a liquid crystal molecule to complete its rotation before the next frame is rendered. The result is a shadow or semi-transparent streak that lingers behind a moving element, anchored to its previous frame position. It is a limitation of the technology itself, not the graphics card or game engine.

Motion blur, by contrast, is a perceptual smear caused by the eye tracking a moving element across a sample-and-hold display. Even a unit with near-instant pixel response still produces smearing because the image is held static on screen for the full duration between refreshes. At standard rates, each frame persists for approximately 16.67ms — enough for the eye to perceive significant smearing during fast horizontal movement. This is why higher refresh rates reduce perceived smearing even when pixel transitions are unchanged: shorter frame retention means less inter-frame hold time for the eye to integrate across.

Pixel Response Time and Why It Causes Dark Trailing

Pixel response time, measured in milliseconds, describes how long a pixel takes to complete a color transition — for example, a gray-to-white transition or a black-to-gray shift. The marketing figure you see advertised as 1ms GtG (gray-to-gray, also written grey-to-grey or grey-to-gray) represents the single fastest transition the technology can achieve — typically a mid-gray to lighter gray. In reality, average transition speed across all color steps is typically 2–5× the advertised spec. A unit marketed as 1ms GtG may have a real average of 4–8ms, and dark transitions on VA technology can reach 15–40ms.

This matters because ghosting is driven by the slowest transitions, not the fastest. The liquid crystal rotation involved in dark transitions is inherently slow — the molecular alignment required to reach very dark states simply takes more time, even when applied voltage is maximized. No amount of software adjustment eliminates this fundamental physics constraint.

MPRT vs GtG: What the Response Time Numbers Actually Mean

GtG (gray-to-gray) measures pure pixel response — the time for one color level to transition to another. It captures ghosting from slow pixel changes but ignores the sample-and-hold smearing that persists even after pixels finish transitioning.

MPRT (moving picture response time) is the more holistic metric. It combines pixel response with the frame retention effect of a sample-and-hold display, giving a figure that better represents actual perceived motion clarity during element tracking. The relationship is approximately:

At standard cadence, frame hold time is ~16.67ms, so even a unit with 0ms GtG would have an MPRT of ~16.67ms. At faster cadences, frame hold time drops significantly. This is why switching to a higher refresh rate setup dramatically improves motion clarity even when the GtG spec stays the same — MPRT shrinks as frame rate rises. Black frame insertion (BFI) — branded as ELMB by ASUS or DyAc by BenQ — inserts dark frames between real frames to reduce sample-and-hold smearing, cutting MPRT to just a few milliseconds at the cost of luminance reduction and potential flicker from PWM-like strobing.

Panel Type Breakdown — IPS, VA, TN, and OLED Ghosting Performance

Each liquid crystal type and self-emissive technology handles pixel transitions differently, producing distinct ghosting characteristics that the moving block test will reveal:

• TN: Fastest liquid crystal type with average transition speed of 1–4ms. Dark transition speed is relatively fast. Minimal trailing, overdrive adjustment is straightforward. Historically the first choice for competitive play, though color and viewing angle quality are weak.
• IPS: Average transition speed of 3–8ms; Fast IPS achieves 1–3ms. Dark transitions slightly slower than TN but significantly better than VA. IPS ghosting is light and manageable. Fast IPS ghosting now approaches TN levels. Medium or Normal overdrive is typically the optimal setting.
• VA: Bright transitions of 3–5ms are acceptable, but dark transitions of 15–40ms create severe ghosting — the notorious VA smear visible as dark trailing in low-light content. VA dark ghosting is the worst of any liquid crystal type. Overdrive has limited improvement for dark transitions; even aggressive settings cannot fully resolve the slow molecular alignment problem. Premium VA designs have improved but still cannot match IPS or self-emissive alternatives.
• OLED: Transition speed of 0.03–0.1ms — microsecond-level response that makes self-emissive ghosting effectively zero in the traditional sense. All color transitions are virtually instant. No overdrive setting exists or is needed. Self-emissive technology still exhibits sample-and-hold smearing (same as any hold-type display), so motion clarity improves with higher refresh rates and BFI. Self-emissive units also carry burn-in risk under static content.

How Refresh Rate Affects Motion Clarity and Perceived Blur

The screen refresh rate — measured in Hz — determines how many new frames your output draws per second and, crucially, how long each frame persists before being replaced. At standard cadence, frame hold time is 16.67ms. At 144Hz it drops to 6.94ms. At 240Hz it falls to 4.17ms. At faster pro-level cadences, frame hold time is under 3ms.

This reduction in frame retention directly shortens MPRT, making elements appear sharper and reducing perceived smearing even without any change in pixel response speed. The jump from standard to 144Hz is the most dramatic step — most users notice the improvement in camera movements and fast-paced games immediately. The step to 240Hz is smaller but meaningful for competitive players who depend on target acquisition during rapid camera movements. A 100Hz output sits between these tiers and offers a meaningful improvement over standard cadence for office and video playback use.

Overdrive and Inverse Ghosting — Finding the Optimal Overdrive Setting

Overdrive (OD) is a pixel acceleration technology built into virtually all LCD units. It works by applying overvoltage — temporarily higher voltage — to liquid crystal molecules to force them to rotate faster than they naturally would, completing color transitions more quickly. It is typically controlled through the on-screen menu under labels like "Response Time," "Overdrive," or "OD," with levels usually labeled Off, Normal (or Low), Fast (or Medium), and Fastest (or High/Extreme).

The challenge: overdrive that is too aggressive causes pixels to overshoot their target color value. This pixel overshoot — also called overdrive reverse artifact, corona artifact, or overshoot artifact — creates a bright reverse streak or white ring leading ahead of a moving element. Bright inverse ghosting is typically more visually distracting than the underlying dark ghosting it was meant to fix. The goal of finding the right overdrive balance is to find the highest level that eliminates trailing without producing visible bright or dark rings. For most units, the Medium or Normal setting provides the best balance. Optimizing a competitive setup requires cycling through each level during a live motion blur test and classifying the result at each step.

Worked Examples — Professional Ghosting Test Scenarios

Scenario 1 — VA Panel User Seeing Dark Trailing Shadows

You own a 27-inch VA unit with an advertised 1ms GtG specification. During the moving block test on a dark background at 600 px/s, you see a long, dark trailing shadow behind each block. Switching to a neutral canvas reduces the streak slightly. Enabling Fast overdrive shortens the streak on bright transitions but the dark trailing in low-light content remains pronounced.

This is the classic VA dark ghosting scenario. The advertised 1ms GtG refers to a specific bright transition — not the dark transitions that dominate low-light content. Dark transition speed on VA technology often measures 15–40ms regardless of the marketing spec. Overdrive can partially reduce trailing on dark-to-gray transitions but rarely eliminates it, and pushing to overdrive fastest creates severe inverse artifacts on brighter content without fully fixing the dark transition problem. The most effective solution is to accept Medium overdrive for a balanced result, increase in-game luminance to reduce dark scene proportion, and recognise that a Fast IPS or self-emissive technology would eliminate this issue at the component level.

Scenario 2 — Competitive FPS Player on a 1ms GtG 240Hz IPS Monitor Still Noticing Blur

You invested in a high-cadence unit with Fast IPS technology, advertised 1ms GtG pixel response time. Your GPU is delivering 200–240 fps. Yet during rapid horizontal camera movements and flicks in competitive play, you still perceive smearing. Running the motion blur test at 960 px/s confirms mostly clean edges with minimal trailing — so pure ghosting is not the issue.

The culprit is sample-and-hold smearing — the MPRT component that persists even after pixels complete their transitions. At high cadence, frame hold time is ~4.17ms. Your unit's effective MPRT is approximately 1ms (GtG) + 4.17ms (frame hold) ≈ 5ms. The eye tracking a fast-moving element across a hold-type display introduces perceptual smearing that no amount of overdrive adjustment can fix, because it is not caused by slow pixel transitions at all. Enabling BFI (ELMB or DyAc) reduces the frame hold time contribution to near zero, cutting perceived smearing dramatically. Alternatively, switching to an even faster cadence setup reduces frame hold time further, narrowing MPRT. This scenario illustrates why MPRT vs GtG matters: a display test that only measures trailing misses half the motion performance picture.

Scenario 3 — Office Laptop User at 60Hz Noticing Smearing During Scrolling

You are working on a standard-cadence output — a typical office setup or laptop — and notice that scrolling text appears to smear, making page navigation and video motion uncomfortable. Running the moving block test at 240 px/s reveals moderate trailing. At 600 px/s the output shows severe smearing. Enabling overdrive at Normal reduces some trailing but the experience still feels sluggish compared to a colleague's higher-cadence setup.

At standard cadence, frame hold time is 16.67ms — the dominant factor in perceived motion smearing. Even if your technology's GtG were reduced to zero, MPRT would still be 16.67ms, producing visible smearing during camera movements and scrolling. Overdrive tuning can tighten pixel transitions but cannot overcome the fundamental sample-and-hold smearing at this update rate. The most impactful improvement would be switching to a higher-cadence setup, which cuts frame hold time to 6.94ms and reduces perceived MPRT by more than half — a dramatically more effective solution than any response time setting adjustment. If a system change is not possible, setting realistic expectations and reducing scrolling speed or enabling OS-level smooth scrolling can improve comfort without any component changes.