A feature that attempts to maintain a smooth image when the user takes a picture or records a video without a tripod. Any shakiness in the user's hand can cause a blur in a photo or an uneven sequence of frames in a video. There are two stabilization methods, both of which generally use gyroscopes to detect motion. Optical and Electronic Stabilization Optical image stabilization (OIS) uses an accordion-style bellows that shifts the light between two lenses based on the motion of the camera. The image is stabilized before it reaches the CCD or CMOS sensor. Another OIS technique is the mechanical shift method, which moves the sensor rather than the lens. This allows stabilization to be achieved using ordinary lenses. Electronic image stabilization (EIS), also called "digital image stabilization," examines the difference between video frames and smooths the transition between them via processing. See viewfinder.