Cropping is the removal of unwanted outer areas from a photographic or illustrated image. The process usually consists of the removal of some of the peripheral areas of an image to remove extraneous trash from the picture, to improve its framing, to change the aspect ratio, or to accentuate or isolate the subject matter from its background. Depending on the application, this can be performed on a physical photograph, artwork, or film footage, or it can be achieved digitally by using image editing software. The process of cropping is common to the photographic, film processing, broadcasting, graphic design, and printing businesses.
In certain circumstances, film footage may be cropped to change it from one aspect ratio to another, without stretching the image or filling the blank spaces with letterbox bars.
Concerns about aspect ratios are a major issue in filmmaking. Rather than cropping, the cinematographer usually uses mattes to increase the latitude for alternative aspect ratios in projection and broadcast. Anamorphic optics (such as Panavision lenses) produce a full-frame, horizontally compressed image from which broadcasters and projectionists can matte a number of alternative aspect ratios without cropping relevant image detail. Without this, widescreen reproduction, especially for television broadcasting, is dependent upon a variety of soft matting techniques such as letterboxing, which involves varying degrees of image cropping.
Since the advent of widescreen television, a similar process removes large chunks from the top & bottom to make a standard 4:3 image fit a 16:9 one, losing 25 percent of the original image. This process has become standard in the United Kingdom, for television programs in which many archive clips are used. This gives them a zoomed-in, cramped image with reduced ??. Another option is a process called pillarboxing, where black bands are placed down the sides of the screen, allowing the original image to be shown full-frame within the wider aspect ratio. See this article for a fuller description of the problem.