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.

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.

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.

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. 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

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

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.

Automatic – Manual
With new releases (e.g. a 2.35: 1 movie for a 16: 9 DVD) cropping is often inevitable. In addition to the selection of the target format, the decision between automatic and manual cropping is also necessary here:

Automatic Cropping
The image section is defined once for the entire film and then requires no further intervention during the conversion. This is the cheapest, but can sometimes destroy the composition. In extreme cases, entire scenes appear pointless; Typical examples here are Cinemascope Westerns with duel scenes, in which the 4: 3 TV version shows both duelists outside the visible picture.

Manual cropping
The image section is determined for individual scenes or individual camera settings based on artistic criteria. Sometimes the image section is constantly shifted during a scene or letterboxing accepted for individual scenes. The additional costs for this process are typically just under € 1000 for a 90-minute feature film; like color correction, it is mainly used for high-quality publications.

Explanation of the picture structure:

Frames represent the visible area of the respective aspect ratio.
Blue: 2.35: 1
Red: 1.78: 1 (16: 9)
Yellow: 1.55: 1 (14: 9)
Green: 1.33: 1 (4: 3)

The area of the image that is no longer visible due to cropping is displayed darker.
The frames of the larger aspect ratios are displayed; the frames that are within the visible image are hidden so as not to interfere. The inserted “letter boxes” represent the picture in the 4: 3 aspect ratio as a percentage as it would appear on a 4: 3 television set. This is not similar to the picture on a 16: 9 television set.

Compromise
In the UK, 16: 9 films occasionally “cropping” the image to 14: 9 (1.55: 1), in which a little of the image content on the left and right is lost, but only a small black stripe is created. This is also done the other way round at 4: 3, but the image content is shortened at the top and bottom. While there is a general 16: 9 broadcast requirement for new productions, there are enough viewers with old 4: 3 televisions, and this is the reason for this compromise. In Germany there are hardly any programs in 14: 9. Either broadcast in 4: 3 or in the cinema wide formats 1.85: 1 and 2.35: 1. Documentation from “BBC exclusive” is occasionally excluded.

Handling of aspect ratios when buying media in the US
In the United States, film DVD releases are even offered in two versions of the same film. In the original widescreen version, as it was seen in the cinema, and as a 4: 3 Pan & Scan version. So you can decide whether you would rather have the cinema feeling at home, or if you prefer to have the screen completely and effectively filled.

High Definition TV
With the introduction of HDTV and a fixed aspect ratio of 16: 9, a “cropping” of the 4: 3 picture of old material is used, in which the black stripes do not appear above and below the picture, but to the left and right of it.

Digital video
With digital video cameras (DV) it is used to save memory (an option many MJPEG cards), or because it is the DV standard with 704 visible lines, as opposed to the full PAL -Resolution so dictates.

Image editing
In image processing, cropping creates an image section that does not necessarily have a fixed aspect ratio as in film. It can also be aligned outside the center of the image or vertically. The original aspect ratio can also be preserved or another can be created by trimming to the main motif in accordance with the format. In addition to improving the image composition, cropping with a fixed aspect ratio is used to maintain a uniform appearance and to adapt it to standard formats, e.g. for expression.

Painting and drawing
In painting, the “frame” designates the frame. The term cropping would be ambiguous and not common. We talk about “decrease”.

Church painting is quite often cropped or enlarged with a more or less roughly painted strip, in order to adapt exactly to the new chapel where it must be hung. It has happened that owners have valued the frame more than the paint, and cut it down to fit it into the frame.

We trim a table to split it into several smaller ones that are easier to place and sell. We were thus able to dismantle a group portrait into several individual portraits, thereby eliminating a character that we want to avoid commemorating.

Tables are also trimmed to change their shape, from the rectangle to the oval or to the bezel above the door, or to eliminate a deteriorated part.

In drawing, the cropping of a sheet is quite common, to isolate a study or a sketch to highlight or to assemble sheets of various formats in an album.