Rolling shutter
Rolling shutter is a process of image capture in which a still picture (in a still camera) or each frame of a video (in a video camera) is captured not by taking a snapshot of the entire scene at a single instant in time but rather by scanning across the scene rapidly, vertically, horizontally or rotationally. Thus, not all parts of the image of the scene are recorded at the same instant – however, during playback, the entire image of the scene is displayed at once, as if it represents a single instant in time.