When 24P content runs untouched on a 60Hz device, issues may emerge if the playback device doesn’t have good optimization for 24fps. Because there are effectively 48 frames per second missing from the standpoint of the TV or projector, viewers are likely to experience considerable judder, especially when the camera pans or during fast-moving scenes.
Motion smoothing, motion enhancement, or image interpolation adds the missing 48 frames to increase 24fps up to the native 60fps or 60Hz of the TV or projector. The quality of this speeding up varies by the capabilities of the onboard CPU and other components. If done properly, problems like judder, poor shadow definition, and detail loss due to blur are kept at a minimum. However, people sensitive to frame insertion will notice this and complain about the unrealistic nature of the soap opera effect.
While motion smoothing inserts duplicates of existing frames to fluff up the frame rate, motion blur employs black frame insertion. In other words, frames are blank and don’t have any visual data. Both of these try to “fool” our brains into not seeing them and thus present smooth 60Hz content with no judder, jitter, or overly intrusive blur. But not only do many people complain that these enhancement effects result in visuals that appear fake and unreal, flicker also happens quite often if motion smoothing and motion blur aren’t handled well, leading to eye strain.