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Concept
High-definition video
Résumé
High-definition video (HD video) is video of higher resolution and quality than standard-definition. While there is no standardized meaning for high-definition, generally any video image with considerably more than 480 vertical scan lines (North America) or 576 vertical lines (Europe) is considered high-definition. 480 scan lines is generally the minimum even though the majority of systems greatly exceed that. Images of standard resolution captured at rates faster than normal (60 frames/second North America, 50 fps Europe), by a high-speed camera may be considered high-definition in some contexts. Some television series shot on high-definition video are made to look as if they have been shot on film, a technique which is often known as filmizing.
The first electronic scanning format, 405 lines, was the first high definition television system, since the mechanical systems it replaced had far fewer. From 1939, Europe and the US tried 605 and 441 lines until, in 1941, the FCC mandated 525 for the US. In wartime France, René Barthélemy tested higher resolutions, up to 1,042. In late 1949, official French transmissions finally began with 819. In 1984, however, this standard was abandoned for 625-line color on the TF1 network.
Modern HD specifications date to the early 1980s, when Japanese engineers developed the HighVision 1,125-line interlaced TV standard (also called MUSE) that ran at 60 frames per second. The Sony HDVS system was presented at an international meeting of television engineers in Algiers, April 1981 and Japan's NHK presented its analog high-definition television (HDTV) system at a Swiss conference in 1983.
The NHK system was standardized in the United States as Society of Motion Picture and Television Engineers (SMPTE) standard #240M in the early 1990s, but abandoned later on when it was replaced by a DVB analog standard. HighVision video is still usable for HDTV video interchange, but there is almost no modern equipment available to perform this function. Attempts at implementing HighVision as a 6 MHz broadcast channel were mostly unsuccessful.
Source officielle
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