Anamorphic image recording means the storage or transmission of images that have been distorted in one dimension. Scaling to the correct aspect ratio (Aspect Ratio ) is required for the correct displaying of the images.
The method is not limited to DVD playback or the 16:9 format, but found, for example also in the storage of CinemaScope material on 35 mm film application. The following description uses the example of storage of 16:9 material in DVD format because it can understand most of the readers here.
If a wide-screen picture to be coded, two ways to offer:
- The proportions are retained and the image is shrunk until the image width is suitable for a 4:3 screen TV. Up and down then, however, areas remain without image information; the image appears as a letterbox slot considered - hence the name letterbox.
The disadvantages are that not all the pixels available (or space on a 35 - mm film ) are exploited. Also see viewer on a 16:9 TV then not only the co-assigned horizontal black bars, but also additional " Bookends ", ie bookends, called vertical black areas. Although the 16:9 TV offer you the ability to zoom into the picture, the result of this interpolation flickers but occasionally; especially in horizontal patterns, the image appears restless.
- The other solution, is not mitzukodieren the black bars and fill all lines with image information. However, since more than 720 points are allowed in the horizontal plane in the PAL standard and in the DVD standard, the images must then be pushed together horizontally by 25%.
For playback on a 16:9 TV the TV this " anamorphic " image equalized again to the correct width. For a 4:3 screen TV turn the DVD player compresses the image vertically and generates up and down the black bars as a filling. A good DVD player is anamorphic and letterbox formatted movies on a 4:3 TV dar. same for many players this interaction diving is not well implemented, appear particularly during camera movement in this case, undesirable patterns in the image on a 4:3 - TV. Newer 4:3 TV can also display anamorphic 16:9 without loss of content.
However, owners of widescreen TVs despite anamorphic see this imagery in some films horizontal black bars. In such cases, the film was then in a widescreen format as Cinemascope or Panavision with an aspect ratio of 2.35:1, 2.40:1 or filmed (after 1970) ( 2.76:1 rarely before 1970 ).
To not here yet again to have to cut margins, compromising the vertical resolution can be made - this bar are different than those produced only in the player letterbox bars, integral part of data stored on the DVD artwork. Will CinemaScope / Panavision movies shown on a 4:3 player, then you can see both the letterbox bars and the firm contained in the image; with some DVDs, the transition is also visible through a slightly lighter line or by a minimum gradation.
Anamorphic encoded widescreen has a PAL resolution of 720 × 576 ( or 704 × 576 ) pixels. Equalization does not change the number of pixels, but the image moves to the width, making it appear in the correct aspect ratio takes place.
It is not always possible to detect on a DVD packaging in which format the movie is actually stored. For "widescreen " anamorphic both coded as mean and letterboxing.