ⓘ Cropping (image)

                                     

ⓘ Cropping (image)

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.

                                     

1. Cropping in photography, print & design

In the printing, graphic design and photography industries, cropping is the removal of unwanted areas from the periphery of a photographic or illustrated image. Cropping is one of the most basic photo manipulation processes, and it is carried out to remove an unwanted object or irrelevant noise from the periphery of a photograph, to change its aspect ratio, or to improve the overall composition. In telephoto photography, most commonly in avian and aviation photography, an image is cropped to magnify the primary subject and further reduce the angle of view -- when a lens of sufficient focal length to achieve the desired magnification directly was not available. It is considered one of the few editing actions permissible in modern photojournalism along with tonal balance, color correction and sharpening. A cropping made by trimming off the top and bottom margins of a photograph, or a film, produces a view that mimics the panoramic format in photography or the widescreen format in cinematography and broadcasting. Neither of these formats is cropped as such, but rather they are products of highly specialized optical configurations and camera designs.

                                     

2. Cropping in cinematography and broadcasting

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 fig. 2.

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 see figures 2, 3 and 4.

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. 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 fig. 6. See this article for a fuller description of the problem.

  • Typical cropping in cinematographic and broadcast applications
                                     

3. Additional methods

Various methods may be used following cropping or may be used on the original image.

  • Vignetting is the accentuation of the central portion of an image by blurring, darkening, lightening, or desaturation of peripheral portions of the image
  • The use of nonrectangular mat or picture frame may be used for selection of portions of a larger image
                                     

4. Uncropping

It is not possible to "uncrop" a cropped image unless the original still exists or undo information exists: if an image is cropped and saved without undo information, it cannot be recovered without the original.

However, using texture synthesis, it is possible to artificially add a band around an image, synthetically "uncropping" it. This is effective if the band smoothly blends with the existing image, which is relatively easy if the edge of the image has low detail or is a chaotic natural pattern such as sky or grass, but does not work if discernible objects are cut off at the boundary, such as half a car. An uncrop plug-in exists for the GIMP image editor.

                                     
  • ears as a punishment Cropping animal cutting the ears of an animal shorter, usually trimming to shape the pinnae Cropping image to remove unwanted
  • a new image by selecting a desired rectangular portion from the image being cropped The unwanted part of the image is discarded. Image cropping does not
  • compared to 35 mm film format results in cropping of the image This latter effect is known as field - of - view crop The format size ratio relative to the
  • manually adjust the orientation of an image or image sequence without needing to re - encode it. Cropping enables the image to be re - framed without re - encoding
  • Image stabilization IS is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure
  • Automatic cropping to maximum image area Optional automatic completion of missing image parts helpful for sky, clouds, grass, gravel etc. No image size limitation
  • effectively cropping out the edges of the image that would be captured by the 36 mm 24 mm full - size film frame. Because of this crop the effective
  • Core Image is a pixel - accurate, near - realtime, non - destructive image processing technology in Mac OS X. Implemented as part of the QuartzCore framework
  • computer vision, image segmentation is the process of partitioning a digital image into multiple segments sets of pixels, also known as image objects The
  • all feature an image of a crop circle that appeared in East Field in Alton Barnes, Wiltshire. On the night of 11 12 July 1992, a crop - circle making competition