High definition (HD) is the term for digital broadcasting and viewing that offers higher resolution, higher frame rate and an improved aspect ratio compared to standard definition (SD) television. This provides a clearer picture and theater-quality surround sound audio.
History
The first public broadcast in HD was in 1996, but the technology was held back for years by disputes between manufacturers. The FCC-mandated NTSC (National Television Systems Committee) and later the ATSC (Advanced Television Systems Committee) created the standard, and with improved technology including digital compression, HDTVs eventually took hold in the marketplace.
Screen Resolution
While SDTVs offer 720 (horizontal) x 480 (vertical) lines of resolution on the screens, HDTVs have up to 1920 x 1080 lines, which makes for a sharper, more detailed picture.
Aspect Ratio
HDTVs have a wider, more rectangular 16:9 aspect ratio, similar to that of movie theater screens, as opposed to the more square-shaped 4:3 aspect ratio of older SDTVs.
Audio
With HD signals being digitally transmitted, HDTVs also offer Dolby Digital 5.1 channel surround sound audio along with the sharper picture--a big upgrade over the two-channel stereo audio of SDTVs.
Potential
With the United States switching to digital-only broadcasting by June 2009, and with the increasing popularity and affordability of HDTV, it's only a matter of time before the only TVs sold in stores will be HDTVs.
Tags: aspect ratio, HDTVs have, sound audio, surround sound, surround sound audio, Systems Committee, Television Systems
