I’m taking a quick break from filming to tell you the best way to watch Mission: Impossible Fallout (or any movie you love) at home. pic.twitter.com/oW2eTm1IUA
— Tom Cruise (@TomCruise) December 4, 2018
Anyone who owns a high-definition TV has likely experienced the nagging sensation of something being not quite right when watching films. It's not all in your head. The effect is called video interpolation, or motion smoothing, and last night, Tom Cruise and writer/director Chris McQuarrie dropped a surprise PSA on Twitter (apparently filmed on the set of Mission Impossible: Fallout) to warn us about this evil.
Okay, so motion smoothing isn't actually evil. It's more of a double-edged sword. The feature is great for watching sports, but it makes movies look like "they were shot on high-speed video rather than film," says Cruise. In other words, your Hollywood blockbuster movie will look like a 1970s BBC TV series. That's why it's commonly called "the soap opera effect."
Why does this happen? Essentially, the feature uses image processing algorithms to insert (interpolate) "extra" frames between the actual frames. The TV will process one frame, then another, and then the algorithms will try to guess what a new frame inserted between those two frames should look like. This increases the frame rate to 120fps, to match the HDTV's 120Hz refresh rate. It will smooth out the image and make fast-paced events easier to follow, like basketball games or NASCAR races—or even the nightly news, which isn't meant to look cinematic. But it won't have that "film" feeling anymore: it feels "unnatural," or rather, a bit too real, ruining the illusion.