What is HDTV? EDTV? SDTV?
UHD, HDTV, SDTV, Analog: What is the Difference?
Continued from page 1
Enhanced-Definition TV - EDTV was briefly available as a bridge between SD and HD, like analog TV, it 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 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 are down-converted to fit the native resolution of an EDTV. While it isn't HD, it was commonly held that HD broadcasts on EDTV look nearly as good as on an HDTV.
High-Definition TV - HDTV came in three flavors, 720p, 1080i and 1080p; really there were 18 DTV formats, but most TVs used 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. Broadcasters still do not broadcast in 1080p, in fact they may skip over it in favor of a 4K UHD standard. Currently, all new HD televisions manufactured have an aspect ratio of 16:9.
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Analog broadcasting ended in 2009 in the U.S.A., replaced by digital broadcasts. Certain low power stations may still broadcast an analog signal. HD broadcasts are what HDTVs are all about, so the picture is excellent on any resolution HDTV. DVD progressive scan can be displayed on a 1080p TV, it will be up-converted from its 480p native resolution. Blu-Ray's maximum resolution is 1080p and the image quality is nearly filmlike. However, 4K UHD will ultimately replace Blu-Ray discs.
Ultra-High Definition Television - UHD or 4K TVs display a resolution of 3840 pixels by 2160 lines (2160p using the old nomenclature). The resulting pixel density is four times greater than an HD television, yielding an 8.3 megapixels image (versus about 2 megapixel for HD). The next generation may be an 8K TV however, due to limits of human vision the improvement may be difficult to see.
Page 1: Back to Analog and SDTV
