The Basics of Slitscan Technique

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Artist-photographer Adam Magyar  in front of his slitscan photograph installation 

The slit-scan photography technique is a photographic and cinematographic process based upon the camera's relative movement in relation to a light source.  By combining camera's long exposure time and a moveable slide with a slit-shaped aperture set directly in front of the camera, a certain part of the subject seen through the slit is being exposed at one time and the camera captures it as a single photograph.  As the slit travels across the camera, the step is repeated for each frame and produces a consecutive light trail from the first to the last frame of the image. In other words, the entire process captures an image revealing the trail of subject's time-based movements in deformed fashion.  

This technique was traditionally used in static photography with standard film photography camera and was perfected for the creation of spectacular animation and became widely used for motion pictures. In today's digital realm, a chain of image slices are extracted from a sequence of video frames, and combined into an image sequence.

It goes probably without even mentioning, one of the most prominent adaptations of this technique can be seen in the "Stargate" sequence in Stanley Kubrick's 2001: A Space Odyssey which was created by Yoda of modern special effects,  Douglas Trumbull .

Reference: Underview on 2001: Slitscan, 2001 A Space Odyssey: Unwrapping the Slit Scan sequences, Slit Scan and Strip Photography Overview,  Adam Magyar’s Slit-Scan Camera