Letter & Pillar refer to methods in image processing and video technique in which an image usually black borders added. The aim is the adjustment of the aspect ratio of an image, such as the aspect ratio of a screen. In letterbox at the top and bottom beams, such as in the conversion of an image between 16:9 4:3. The other direction is called Pillar; the bars are the right and left available. These methods serve as an alternative to non-proportional distortion of the image.
The name " letterbox" refers to the shape of the openings of mailboxes. The name " Pillar " is derived from the usual UK columnar mailboxes.
Pillar on German television
During the HDTV simulcast test operation of ProSieben was upscaled image points with the exception of the announced highres movies the normal SDTV signal of 720 × 576 ( 4:3) pixels on HDTV resolution of 1920 × 1080 (16:9). The movies in 4:3 format and the films themselves were included letterbox to 1440 × 1080 pixels upscaled to 16:9 and then brought to a resolution of 1920 × 1080 with the Pillar bar. In the meantime set control operation of Sat.1 HD and ProSieben HD from October 26, 2005 pillarboxing was again applied, but the unused Pillar bar enriched with additional information.