Motion Interpolation Motion-compensated frame interpolation (MEMC)

What motion interpolation is

Motion interpolation, also called motion-compensated frame interpolation, is a form of video processing in which intermediate frames are synthesized between existing ones. The TV estimates where objects move between two real frames and draws a new frame in between. On a 120 Hz panel showing 24 fps film, it can insert four synthetic frames for every real one. The result is smoother pans and less blur, and for cinema it is the "soap opera effect," because soap operas were often shot at 60 Hz while theatrical films run at 24 fps, per Wikipedia.

How it works

LG's support page explains the mechanism on its own implementation. At 120 Hz, TruMotion inserts an interpolated frame between the previous and next frames using motion estimation and compensation. At 240 Hz it combines that interpolation with backlight scanning so each image stays on screen for a quarter of its normal time. Wikipedia describes the same arithmetic for 120 Hz sets showing 24 fps content: each real frame is shown five times without interpolation, which needs no 3:2 pulldown, and interpolation is only needed when the target rate does not divide evenly.

Worked example. A 24 fps film frame lasts 41.7 ms. On a 120 Hz panel with interpolation, that interval is filled by one real frame and four synthetic frames, each held for 8.3 ms. Without interpolation, the same real frame is repeated five times for 41.7 ms. The synthetic frames are guesses, so fast pans, text and hair produce artifacts. Wikipedia notes artifacts are more pronounced on cheaper TVs and show up as glitches during fast camera pans. The processing also costs time: Wikipedia puts typical added latency at about 10 ms, with some implementations above 80 ms. See input lag.

Brand names and where the setting lives

Every maker uses its own label. LG calls it TruMotion, with presets Smooth, Clear, Clear Plus and User, where User exposes de-judder and de-blur sliders and de-blur is only available on 240 Hz models. Samsung calls it Auto Motion Plus (Picture Clarity in some menus) under Settings, Picture, Expert Settings. Its default is Auto, which switches processing by program type, and the Custom setting exposes Blur Reduction, Judder Reduction and LED Clear Motion. Samsung's support page notes that live TV is filmed at 30 frames per second, while most movies are filmed at 24, and says the effect appears on movies. A glossary entry from Forasoft lists Motion Plus and Motion Flow as TV features that reduce judder by generating intermediate frames at the price of the soap opera effect. Sony markets its version as Motionflow; I did not load Sony's support page, so I cannot describe its settings.

Motion interpolation vs Filmmaker Mode vs BFI

The Filmmaker Mode preset exists to switch this off. The UHD Alliance announced it on 27 August 2019, and Engadget reports that it turns off motion smoothing and sets the correct color, aspect ratio and frame rate, either through metadata on a disc or stream or with one remote button. LG, Vizio and Panasonic were named backers. The mode is a preset, so it only applies while selected.

Black frame insertion is a different fix for a different problem. Interpolation adds synthetic frames to smooth motion, while BFI adds dark intervals to reduce persistence blur and creates no new motion detail. The judder entry covers why OLED needs one or the other to hide 24p stutter.

Two 2025 formats try to make smoothing a creative choice instead of a global toggle. HDR10+ Technologies lists Intelligent Motion Smoothing in HDR10+ Advanced: metadata that addresses visible judder and lets a compatible display adjust the amount of smoothing it applies in each scene. Dolby calls Authentic Motion in Dolby Vision 2 "the world's first creative driven motion control tool," applied shot by shot, and in its 6 August 2026 Hisense release it places the feature in the Max tier, reducing judder and soap-opera effects in newly authored titles. Both reduce the need for a viewer-set slider, but neither has a published measurement in the sources I read.

For movies and scripted TV, turn interpolation off or to its lowest user setting and let the TV repeat frames cleanly. For live sports shot at 30 fps or higher, a mild setting reduces blur and rarely looks artificial. For games, leave it off, because the extra 10 ms or more of latency is real. If you cannot find the control, search the picture menu for the brand names above, and use Filmmaker Mode or Cinema as a reset. Calibrators treat it as one line in a calibration checklist.

Common confusions

"240 Hz" or "Motion Rate 240" on a spec sheet can mean either a 240 fps native display with interpolation or a 120 Hz panel with a strobing backlight, per Wikipedia, so it does not tell you the panel's true refresh rate. Wikipedia describes the 240 fps version as inserting 2 to 8 synthetic frames between source frames, depending on whether the source is 60 or 24 fps. Interpolation is also not the same as native high frame rate content: it invents frames, while a 60 fps source contains real ones. And turning it off does not remove 24p judder, which is a cadence and hold-time issue covered separately.