What is EDTV Resolution?
Reviewer: Phil Conner
What is an Enhanced Definition (EDTV) TV? It is simply a TV—be it a plasma television, or other technology that has 853 x 480 native pixel resolution.
We have all heard certain plasma displays described as "enhanced" definition displays. "Enhanced" certainly makes these plasma TVs sound good … desirable even. Lucky for us there's more to this than just clever marketing. Enhanced-definition (or ED) plasma TVs are actually better than conventional, tube-type TVs—not just slimmer and wider.
Let me explain: Standard-definition (SD) TV—the sort most of us have been watching for years—has 480 visible lines of detail. This is the number of horizontal lines found on your TV screen. Remember, TVs are measured on the diagonal: The width of the screen changes, while its height remains more or less constant. Thus, it is the number of pixels on the vertical axis that really determines how much detail is visible.
Like SDTV, EDTV contains 480 horizontal lines of picture detail, but the difference is that these 480 lines are displayed differently on standard- versus enhanced-definition televisions. SDTV utilizes a process called "interlacing" to display these 480 active lines of information. An interlaced picture is actually a single frame of video "painted," line-by-line, onto the screen in two passes. On the first pass, all the odd numbered lines from top to bottom (i.e., numbers 1, 3, 5, … 479) are displayed. This takes 1/60th of a second to accomplish. In the next 1/60th of a second, all the even lines are painted. So, it takes exactly 1/30 of a second to display a full picture at 480i ("i" for "interlaced"). The refresh rate of such displays is 30 Hz.
With EDTVs, these 480 lines are displayed progressively, meaning all the lines are "painted" onto the screen sequentially (1, 2, 3, … 480) in one pass as opposed to two. Which essentially means that more information can be displayed with progressive scanning since there is not 1/60 of a second lag between "takes." What would otherwise take 1/30 of a second to be displayed using interlacing can actually be shown in half the time progressively. Progressive-scan formats provide full vertical resolution at all times, at a refresh rate of 60 Hz. Hence the enhanced picture quality that comes with progressive scanning.
Which is why EDTV has been called by some the biggest advance in video quality since color TV. Now, HDTV plasma is taking center stage as prices come down quickly on LCD and Plasma TVs. The simple anwer on what a HDTV plasma would be is 1024 x 768 resolution or higher (1366 x 768 is common on 50" plasma, and 1024 x 768 resolution is common on 42" plasma TVs).If you want to learn more about how enhanced-definition plasma TVs stack up against high-definition ones, see my article, "EDTV Plasmas Vs. HDTV Plasmas: Drawing Some Conclusions About Native Resolutions".
If you want to learn more about how enhanced-definition plasma TVs stack up against high-definition ones, see my article, "EDTV Plasmas Vs. HDTV Plasmas: Drawing Some Conclusions About Native Resolutions".
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