Cropping is the process of removing undesired parts from a photograph or illustration. The technique typically entails removing some of an image's peripheral areas in order to remove unnecessary rubbish from the image, improve its frame, adjust the aspect ratio, or emphasize or isolate the subject matter from its background. This can be done on a real photograph, artwork, or film footage, depending on the application, or it can be done digitally using image editing software. Cropping is a technique used in the photographic, film processing, broadcasting, graphic design, and printing industries.
In photography, print, and design:
Cropping is the removal of undesired regions from the periphery of a photographic or illustrated image in the printing, graphic design, and photography industries. Cropping is one of the most fundamental photo alteration techniques, and it is used to eliminate an unwanted object or unnecessary noise from the periphery of a shot, adjust its aspect ratio, or improve its overall composition.
When a lens of adequate focal length to accomplish the desired magnification directly was not available, an image is cropped in telephoto photography, most typically in avian and aviation photography, to magnify the primary subject and further restrict the angle of view. Along with tonal balance, color correction, and sharpening, it is regarded as one of the few editing actions permitted in modern photojournalism. Cropping an image or a film by removing the top and bottom margins creates a view that resembles the panoramic format (in photography) or the widescreen format (in cinematography and broadcasting). Neither of these formats is cropped in the traditional sense; rather, they are the result of highly specific optical combinations and camera designs.
In cinematography and broadcasting:
In some cases, film footage can be cropped to modify its aspect ratio without extending the image or filling the vacant gaps with letterbox bars.
Aspect ratio concerns are a fundamental difficulty in filmmaking. Instead of cropping, the cinematographer would typically employ mattes to improve the latitude for different aspect ratios in projection and broadcast. Anamorphic optics (such as Panavision lenses) generate a full-frame, horizontally compressed image from which broadcasters and projectionists can produce a variety of different aspect ratios without losing image information. Without it, widescreen reproduction, particularly for television broadcasting, is reliant on a number of soft matting techniques, including letterboxing, which entails variable degrees of image cropping.
Since the introduction of widescreen television, a similar procedure has been used to remove big sections from the top and bottom to make a conventional 4:3 image fit a 16:9 one, resulting in a loss of 25% of the original image. Another alternative is pillarboxing, which involves placing black bands down the sides of the screen to allow the original image to be viewed in full frame.
It is not possible to "uncrop" a cropped digital image unless the original still exists or undo information exists: if an image is cropped and saved (without undoing information), it cannot be recovered without the original.
However, texture synthesis can be used to artificially add a band around a picture, effectively "uncropping" it. This works if the band blends nicely with the existing image, which is relatively easy if the edge of the image has little detail or is a chaotic natural pattern like sky or grass, but it does not work if visible items are cut off at the boundary, like half a car. For the GIMP image editor, there is an uncropped plug-in.