VERFAHREN UND SCHALTUNG ZUR DECODIERUNG VON LETTERBOX-SIGNALEN

摘要

The existing compatible transmission of 16:9 images in the current PAL television standard has a few drawbacks. Firstly, the first line of the video image is only half-filled with video information. This line usually disappears in the overscan region of the receiver and is therefore invisible. In the necessary format conversion for a 16:9 image, this line is nevertheless transferred to the first visible line of the letter-box image and thus returns to the visible part of the television image. Secondly, between the corresponding lines of the first and second partial image there is a time delay of 313 lines. This hampers the desired colour coding. Therefore the first partial image is displaced by one line in relation to the second. In addition, the line at the start of the first partial image and at the end of the second is set to black before the format conversion. The helper lines are then shifted in this direction before transmission. According to the invention, two of the transmitted helper lines are used to replace this untransmitted line information in the reconstruction of the original lines, thus simplifying read-in and read-out control for the helper and letter-box lines.