Motion Interpolation, also called Frame Interpolation or the Soap Opera Effect, is a form of video processing in which artificial animation frames are generated between existing ones by means of interpolation, in an attempt to make animation more fluid and to compensate for display motion blur.
You probably bought a new TV and you’re wondering why movies look so hyper-real with ultra-smooth motion. You are sure that something is happening with the images shown on the TV that you don’t like, but you can’t figure out what?
Chances are you are seeing something, which is called the “Soap Opera Effect”, which makes, as the name also suggests, everything on your TV look like a cheap soap opera.
The Soap Opera Effect, also just referred to as SOE, is actually a feature of many modern televisions. It’s also called “motion smoothing”, “motion interpolation”, “frame interpolation” or “ME/MC” for motion estimation/motion compensation. It’s a matter of preference, actually. Some people don’t notice it, some hate it and some like it. Mostly, people seem to hate it, because it feels somewhat artificial and unfamiliar, as we’re not used to watch TV with such a high frames per second shown to us.
It was developed to help decrease motion blur on LCDs, as this is a big issue with this type of panel. Motion blur means that any object onscreen, which is in motion will be less detailed (blurry) compared to that same object when stationary. This is why LCDs with higher framerates (120Hz, 144Hz, 240Hz) were developed. In order for these types of displays to be most effective, they must insert new, real frames in-between the original frames.
Thanks to good processors, the TV can “guess” what is happening between the frames in the source footage. These new frames are a “hybrid” of the frame before and frame after. Motion blur will be greatly reduced by using this technique. This work very well with 30FPS and 60FPS source content in particular. Sport is a great example, as the content will have better detail with motion and there are very minimal side effects.
Most movies in Hollywood are filmed with 24FPS, and this creates a problem. The cadence of film, and the associated blurring of the slower frame rate’s image, is linked to the perception of fiction. Even if this perception seems grandiose – the look of 24FPS is expected with movies and fiction TV shows. Even though the TV and movie industry mostly don’t use film anymore, the new digital cameras are set to record at 24FPS, because that’s what the audience expects.
SOE messes with this cadence. Creating frames in-between the 24 original frames makes the movie (24FPS) look like a soap opera (30/60FPS) and this is something that many viewers don’t like.
The other names
Many TV companies have their own name for their frame interpolation processing/algorithm:
- SONY MotionFlow
- Samsung Auto Motion Plus
- Sharp AquoMotion
- Toshiba ClearFrame or ClearScan
- Vizio Smooth Motion
- LG TruMotion
- JVC Clear Motion Drive
Nearly all TV companies allow you to disable SOE (they should too!), and most of them also allow you to adjust its intensity.
SOE is not only an LCD-only issue. TV manufacturers have implemented motion smoothing techniques into the circuitry of plasma displays too. Plasmas generally don’t have an issue with motion blur, so motion smoothing is largely superfluous. What happens inside a plasma TV that uses motion smoothing techniques, is that it creates new frames to insert in-between the film frames, just to make the film smoother.
Panasonic calls its version of this Cinema Smoother. You can find it in the menu under “Motion Picture Setting”.
Frame interpolation allows displays to show a smoother motion than what was originally filmed by creating artificial frames in-between the original frames based on the previous and next frame. If you don’t like it, you can just turn it off and watch movies like you’re used to. You would possibly want this setting on, when you’re watching sports or other 30FPS or 60FPS content.