Cropping (image) - Cropping in Cinematography & Broadcasting

Cropping in Cinematography & 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).

Aspect ratio concerns are a major issue in film making. Rather than cropping, the cinematographer traditionally 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% of the original image. This process has become standard in the United Kingdom, in TV shows where many archive clips are used, which gives them a zoomed-in, cramped image with significantly reduced resolution. This is nonetheless preferred to a process called pillarboxing, where black bands are placed down the sides of the screen, allowing the origial 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

• Figure 1:
  2.35:1 original image with widescreen aspect ratio, showing alternative aspect ratios

• Figure 2:
  2.35:1 image with letterbox resized to 4:3, the whole image is visible

• Figure 3:
  1.85:1 image with letterbox resized to 4:3. Typical 16:9 image, the outer edges of the image are not visible

• Figure 4:
  1.55:1 image with letterbox resized to 4:3. A compromise between 16:9 and 4:3, often broadcast in the UK

• Figure 5:
  1.33:1 image without letterbox, because it is cropped to 4:3, losing much of the original