HDTV, EDTV, SDTV, Analog: What is the Difference?
Continued from page 1
Enhanced-Definition TV - EDTV, like analog TV, displays 480 lines. However, instead of being interlaced, it is a progressive scan image. Progressive scan means that every scan paints a complete image instead of requiring two scans. This results in a smoother image, especially during action sequences, as well as a brighter picture. Nearly all ED televisions have an aspect ratio of 16:9. Just a note, most EDTV displays are plasma panels. Although, most plasma screens are HDTVs.
Analog television broadcasts will appear about the same on an EDTV although the TV circuitry may attempt to enhance the picture. Progressive scan DVDs may look best on EDTV, even better than on HDTVs because they have the same native resolution (480p). HD broadcasts will be down-converted to fit the native resolution of an EDTV. While it isn't HD, many feel that HD broadcasts on EDTV look nearly as good as on an HDTV.
High-Definition TV -
HDTV comes in three flavors, 720p, 1080i and now 1080p; really
there are 18 DTV formats, but most TVs will use one of these
three. The first resolution displays 720 lines progressively
while the second displays 1,080 lines interlaced. Neither is
necessarily better. Presently some stations broadcast in 720p
while others broadcast in 1080i. Whatever the native resolution
of a TV, it will have to interpolate the other signal to fit.
In the future, 1080p will be broadcast and when that happens
it will almost certainly be the best resolution choice. 1080p
should also be fully backward compatible for 720p and 1080i
TVs. Nearly all HD televisions have an aspect ratio of 16:9.
Today's regular analog broadcasts
may appear worse on an HDTV because the flaws of analog broadcasts
are magnified for the large screen. Also, the analog signal
must be up-converted to fit the native resolution of the HDTV.
The number of HD broadcasts are increasing and in the future
analog broadcasts will be discontinued. HD broadcasts are what
HDTVs are all about, so the picture will be excellent on any
resolution HDTV. DVD progressive scan can be displayed on a
720p TV, it will be up-converted from its 480p native resolution.
On a 1080i TV, DVD will also be up-converted but it will be
interlaced, not progressive. High definition DVDs are now available
and the image quality is nearly
filmlike. However, like the old VHS vs: Beta war, hi-def DVDs
are battling between two formats, Blu-Ray vs: HD-DVD.
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