Slit-scan time displacement is a video effect I’ve been seeing more of recently, so I thought I’d compile a few useful references. In particular this test shoot by Adrien M / Claire B (Vimeo profile) is a beautiful example done with a custom Quartz composer plugin:
It isn’t a new effect (the Muse video below dates from 2000) but it does work better with the kind of high-framerate, high-resolution cameras available today.
The effect can be achieved in After Effects using Time Displacement. The basic idea is that different lines of the image are played either at different speeds or displaced to occur at different times. So the result is that the image you see might look like a single frame of video but it’s actually composed of parts taken from several different frames. By shooting a mainly static image, it appears to smear and blend only the moving parts of the image.
The effect works best with high-frame rate footage to get smooth movement. You can also use Twixtor or AE’s TimeWarp to interpolate lower framerates. Also higher resolutions are preferred otherwise you can get a lot of pixelation along moving edges.
EdEditz has an excellent tutorial that covers a couple of different methods in detail.
Finally here’s a couple more examples: