| High-definition Television |
Article Index for High-definition |
Shopping High-definition |
Articles about High-definition Television |
Website Links For Television |
Information AboutHigh-definition Television |
|
in a Home Theater , displaying a high-definition television image.]] High-Definition television ('''HDTV''') means Broadcast of Television signals with a higher Resolution than traditional formats ( NTSC , SÉCAM , PAL ) allow. Except for early analog formats in Europe and Japan , HDTV is broadcasted digitally, and therefore its introduction sometimes coincides with the introduction of Digital Television (DTV). Historically, the term ''high-definition television'' was also used to refer to television standards developed in the 1930s to replace the early experimental systems, although, not so long afterwards, Philo T. Farnsworth , John Logie Baird and Vladimir Zworykin had each developed competing TV systems but resolution was not the issue that separated their substantially different technologies. It was Patent Interference lawsuits and deployment issues given the tumultuous financial climate of the late '20s and '30s. Most patents were expiring by the end of World War II leaving the market wide open and no worldwide standard for television agreed upon. The world used analog PAL, NTSC, SÉCAM and other standards for over half a century. HDTV is defined as 1080 active lines, 16 x 9 Aspect Ratio in ITU-R BT.709. NOTATION In the context of HDTV, the formats of the broadcasts are referred to using a notation describing:
For example, the format 720p60 is 1280 × 720 pixels, progressive encoding with 60 frames per second (60 Hertz known as Hz). The format 1080i50 is 1920 × 1080 pixels, interlaced encoding with 50 fields (25 frames) per second. Often the frame or field rate is left out. It can then usually be assumed to be either 50 or 60, although some displays claim to support 1080p, but only support 1080p/30. Consumer displays are available that allow 1080p/60 input and render it at full temporal and spatial resolution. A frame or field rate can also be specified without a resolution. For example 24p means 24 progressive frames per second and 50i means 25 interlaced frames per second, consisting of 50 interlaced fields per second. Most HDTV systems support some standard resolutions and frame or field rates. The most common are: Standard resolutions Note: this graphic ignores the impact of interlaced artifacts, which would further reduce the vertical resolution
Standard frame or field rates
COMPARISON TO SDTV HDTV has at least twice the resolution of pictures without using Letterboxing , thus further increasing the effective resolution for such content. Close-up view |
{ Class |
"wikitable" |
|