Restriction of the projected or transmitted image area of a film by the use of masks or apertures smaller than the image area available. An aperture of smaller height than the standard academy may be used to show a picture of wide screen aspect ratio. Similarly, cropping of the action at the sides of the picture may take place when a wide-screen print is used for television presentation.
References
1969, The Focal Encyclopedia of Film and Television Techniques, Focal Press, London, New York