Hd Television

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  • Topic: High-definition television, Digital television, NTSC
  • Pages : 10 (3751 words )
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  • Published : March 14, 2011
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HIGH DEFINITION TELEVISION
High Definition Television (HDTV) is a digital broadcast signal that delivers a wide-screen, high resolution picture with six channels of digital sound. High-definition television (or HDTV, or just HD) also refers to video having resolution substantially higher than traditional television systems (standard-definition TV, or SDTV, or SD). HD has one or two million pixels per frame; roughly five times that of SD. Early HDTV broadcasting used analog techniques, but today HDTV is digitally broadcast using video compression. High-definition video or HD video describes any video system of higher resolution than standard-definition (SD) video, and most commonly involves display resolutions of 1,280×720 pixels (720p) or 1,920×1,080 pixels (1080i/1080p). This article discusses the general concepts of high-definition video, as opposed to its specific applications in television broadcast (HDTV), video recording formats (HDCAM, HDCAM-SR, DVCPRO HD, D5 HD, AVC-Intra, XDCAM HD, HDV and AVCHD), the optical disc delivery system Blu-ray Disc and the video tape format D-VHS. HDTVs have the ability to play both television programming and Blu-Ray discs in crystal-clear high definition; they are being used by more people. HDTV SCREEN FORMATS

HDTV provides a much wider screen than conventional television. Because, the viewing area format is similar to a movie theatre screen, the left and right edges of movie presentations don't need to be chopped off. The HDTV wide screen format provides a more intense viewing experience by taking full advantage of the actual human field of vision. The dimension of a television screen is referred to as the aspect ratio. The HDTV television format uses an aspect ratio of 16:9. By comparison, the aspect ratio used by conventional television is almost square (4:3 ratio). While most theatrical movies have used the wide screen format for years, most television programs (until now) have been produced using the old 4:3 narrow screen format. Consequently, when purchasing a High Definition television, it is important to select a model that can displays old television shows without distorting the picture or wasting screen "real estate". Most high definition sets will allow the viewer to select from a variety of display formats. For example, one format will display the legacy television program with a dark area at both the left and right sides of the screen. Another format will crop the top and bottom portions of the television program. More sophisticated technologies will stretch out the 4:3 images horizontally with minimal picture distortion.

TYPES OF HDTVs:
(a)Plasma HDTV generally available in larger screen sizes (50 inches), but is also prone to “burn-in”. This happens when something like a cable channel logo is constantly on screen and its image is burned into the screen permanently. (b)LCD screens are smaller than plasma and have more limited viewing angles, but are also not affected by burn-in. LCD HDTV is typically found in 32-42 inch screens. (c)DLP (Digital light processing) is a newer type of HDTV developed by Texas Instruments. It is less expensive than LCD and produces a better picture for screen action like watching sports. It is also has a good life span, comparable to cathode ray tube televisions.

CAPTURE DEVICES USED: The capture devices used for HDTV are mainly HD cameras and HD camcorders
Fig. 2: HD camera

Hd Camcorders:
HD camcorders allow you to record video in High definition format. Most HD camcorders can record 1080 horizontal lines of an image and offer a huge increase in image quality compared to standard definition camcorders that can only record 400-600 horizontal lines. A HD camcorder will look no different to standard camcorder in it’s appearance but will have better sensors inside able to record a more detailed image. High Definition (HD) video cameras are not all the same. Today, HD video can be produced on consumer grade HD...
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