Ghosting in video is an image artifact in which a faint duplicate or trailing copy of an object appears next to or behind the real one, displaced either in space or in time. In video quality assessment, the term covers several distinct causes that produce a similar look: signal echoes in analog transmission, slow pixel response in displays and temporal processing errors such as frame blending or aggressive noise reduction.
Because the visible symptom is shared but the mechanisms differ, diagnosing ghosting starts by asking where the copy is displaced: sideways in a still image, along the motion path of a moving object, or only across frame boundaries. Each answer points to a different link in the capture, processing, delivery or display chain.
Main types of ghosting in video
Ghosting is best understood as a family of artifacts. The table below groups the common types by where they originate and how they look on screen.
| Type | Where it originates | Typical appearance |
|---|---|---|
| Multipath ghosting | Analog broadcast reception | Offset copy to the right of the whole picture |
| Display ghosting | Slow LCD pixel transitions | Trail behind moving objects |
| Overdrive overshoot | Excessive display overdrive | Bright or dark halo, also called inverse ghosting |
| Frame blending ghosting | Frame rate conversion by mixing frames | Double image of moving objects |
| Temporal filter ghosting | Noise reduction or interpolation in processing | Smeared trails after motion |
| Stereoscopic crosstalk | 3D display leaking one eye’s view | Doubled edges in 3D content |
In modern digital workflows, the most frequent sources are display behavior and temporal processing, while multipath ghosting is mainly a legacy analog phenomenon.
How each mechanism creates a ghost image
Multipath ghosting occurs when an analog signal reaches the antenna both directly and after reflecting off buildings or terrain. The reflected copy arrives later, and because the picture is drawn line by line, the delay becomes a horizontal offset: roughly 1 microsecond of delay corresponds to about 300 meters of extra path. Digital broadcasting systems handle echoes with equalizers and guard intervals, so they rarely show ghosts but may drop out entirely instead.
Display ghosting comes from the time a liquid crystal pixel needs to change from one gray level to another, known as gray-to-gray response time. When a transition takes longer than a refresh period, typically 16.7 ms at 60 Hz or 6.9 ms at 144 Hz, the previous position of an object remains partly visible. Manufacturers apply overdrive, a brief voltage boost, to speed up transitions; too much overdrive creates the opposite halo.
Temporal processing ghosting happens when software combines information from several frames. Frame blending for frame rate conversion mixes two source frames into one output frame, so a moving object appears twice at partial opacity. Temporal noise reduction averages pixels across frames, and if motion compensation fails, details from earlier frames linger as trails.
Ghosting compared with related motion artifacts
Several video quality artifacts affect moving content and are often reported as ghosting by viewers. Telling them apart prevents fixing the wrong stage of the chain.
| Artifact | Visual signature | Typical cause |
|---|---|---|
| Ghosting | Distinct faint copy or trail | Echo, slow pixels or frame mixing |
| Motion blur | Continuous smear without a separate copy | Shutter time or sample-and-hold display |
| Judder | Uneven, stuttering movement | Cadence mismatch such as 24 fps on 60 Hz |
| Combing | Jagged horizontal lines on moving edges | Interlaced fields shown without deinterlacing |
| Mosquito noise | Shimmering noise around edges | Lossy compression of high-frequency detail |
A useful test is to pause playback. If a double image remains in the paused frame, the ghost is baked into the video by processing or capture; if it disappears, the cause is usually the display or its motion processing.
Measuring and diagnosing ghosting
Display ghosting is measured with pursuit camera photography, in which a camera tracks a moving test pattern at the same speed as the eye would, and with photodiode measurements of response times and overshoot percentage. Content ghosting is diagnosed by stepping through frames and comparing them with the source.
| Symptom | Likely cause | Corrective action |
|---|---|---|
| Trail visible only on one monitor | Slow LCD response | Adjust overdrive or use a faster panel |
| Double image in paused frames | Frame blending in conversion | Use motion-compensated or cadence-preserving conversion |
| Smear after fast pans in camera footage | Strong in-camera temporal noise reduction | Lower noise reduction strength |
| Halo brighter than the background | Overdrive overshoot | Choose a lower overdrive setting |
| Copy offset across the whole picture | Analog multipath reception | Reposition or use a directional antenna |
Objective full-reference metrics such as PSNR, SSIM and VMAF can register frame blending as quality loss, but they do not label it as ghosting. Expert viewing on a fast reference display remains the most reliable way to identify the type.
Preventing ghosting in production and delivery
Prevention depends on keeping temporal integrity from capture to screen. The most effective practices are simple but often overlooked.
- Shoot at the delivery frame rate where possible, to avoid later conversion.
- Avoid frame blending for 25 to 30 fps or 24 to 60 fps conversions; prefer cadence methods such as 3:2 pulldown or motion-compensated conversion.
- Limit temporal noise reduction in cameras and encoders, especially for fast sports or gaming content.
- Check deliverables on a fast display, ideally OLED or a well-tuned LCD, before judging motion quality.
- Disable aggressive motion interpolation on review monitors, because it can add its own artifacts.
For viewers, OLED displays with sub-millisecond pixel response practically eliminate display ghosting, although they still show sample-and-hold motion blur at low frame rates.
A non-technical view
Ghosting is when a moving object on screen seems to leave a faint see-through copy of itself behind, like a footprint that fades slowly. Sometimes the copy sits beside the object, sometimes it trails behind it.
The copy can come from an old TV signal bouncing off a building, from a screen that changes its pixels too slowly, or from software that mixes two pictures into one. The look is similar, but the fix depends on which of these is the culprit.
A concrete example
A small production company delivers a 24 fps documentary to a European broadcaster that requires 25 fps. An editor converts it with a quick frame blending preset. On review, the quality control operator pauses a scene with a passing cyclist and sees two semi-transparent bicycles in the same frame.
The company redoes the conversion with a 4 percent speed-up to 25 fps, with audio pitch correction, which keeps every original frame intact. The double images disappear, and the file passes quality control. The editor also notes that the earlier preview monitor had overdrive set to its maximum, which had added bright halos that were never in the file itself.