Pan and scan is a method of adjusting widescreen film images so that they can be shown within the proportions of an ordinary video screen.
Until High Definition Television came onto the scene, television images had approximately the shape of a frame of 35mm film: a width 1.33 times the height (in the industry, referred to as "4:3 aspect ratio"). By contrast, a film image typically has a more rectangular final projected image with an aspect ratio greater than 16:9, often as wide as 2.35 times the height of the image. To broadcast a widescreen film on television, or create a videotape or DVD master it is necessary to make a new version from the original filmed elements. One way to do so is to make a "letterbox" print, which preserves the original theatrical aspect ratio, but produces an image with black bars at the top and bottom of the screen. Another way to turn the 16:9 aspect ratio film into a 4:3 aspect ratio television image is to "pan and scan" the negative.
During the "pan and scan" process, an operator selects the parts of the original filmed composition that seem to be significant and makes sure they are copied—"scanning." When the important action shifts to a new position in the frame, the operator moves the scanner to follow it, creating the effect of a pan shot.
This method allows the maximum resolution of the image, since it uses all the available video scan lines. It also gives a full-screen image on analog television. But it can also severely alter compositions and therefore dramatic effects—for instance, in the film Jaws, the shark can be seen approaching for several seconds more in the widescreen version than in the pan and scan version. In some cases, the results can also be a bit jarring, especially in shots with significant detail on both sides of the frame: the operator must either go to a two-shot format (alternating between closeups in what was previously a single image), lose some of the image, or make several abrupt pans. In cases where a film director has carefully designed his composition for optimal viewing on a wide theatrical screen, these changes may be seen as changing that director's vision to an unacceptable extent.
Once television revenues became important to the success of theatrical films, cameramen began to work for compositions that would keep the vital information within the "TV safe area" of the frame. For example, the BBC suggests program producers frame their shots in a 14:9 aspect ratio to minimize the effects of converting film to television. In other cases film directors reverse this process, creating a negative with information that extends above and below the widescreen theatrical image (this is sometimes referred to as a "full frame" composition). Often pan-and-scan compositors make use of this full-screen negative as a starting point, so that in some scenes the TV version may contain more image content than the widescreen version while in other scenes where such an "opened" composition is not appropriate a subset of the widescreen image may be selected. In some cases (notably many of the films of Stanley Kubrick) the original 1.33:1 aspect ratio of the negative is transferred directly to the video master (although these versions also represent a new aspect ratio compared to the original theatrical release these are not properly "pan and scan" transfers at all but are often called "full-frame" or "open matte" transfers).
Yet some directors still balk at the use of "pan and scan" version of their movies; for instance Steven Spielberg initially refused to release a pan and scan version of Raiders of the Lost Ark, but eventually gave in; Woody Allen refused altogether to release one of Manhattan and the letterboxed version is in fact the only version available on VHS and DVD.