EDTV vs. HDTV native resolutions

 

You're in your local consumer electronics store looking at two 42-inch plasma TVs side by side, and they're playing the same high-def demo footage that stores typically use to make TVs look good. Cosmetically, the two sets appear very similar--until you examine the little price/info placards. One set costs $2,499, the other costs $3,499. You then notice that one is described as an EDTV or Enhanced Definition TV ¹, and the other as an HDTV or high-definition TV. Look a bit closer and you may even notice (depending on the quality of the source) that HDTV plasma looks sharper. Which do you buy?

The fix is in
Welcome to the confusing world of fixed-pixel displays. All fixed-pixel TVs--including every flat-panel LCD and plasma as well as rear-projection microdisplays that use DLP, LCD, and LCoS technology--have a certain number of pixels, known as the native resolution that they use to create the picture. With these types of displays, the native resolution is the absolute limit on the amount of detail you'll see. Fixed-pixel displays follow a few basic rules:

  1. No matter the resolution of the source material, whether VHS, DVD, or HDTV, a fixed-pixel display will always convert, or scale, it to fit its native resolution.
  2. If the incoming source has more pixels than the display's native resolution, you will lose some visible detail and sharpness, though often what you're left with still looks pretty good.
  3. If the incoming source has fewer pixels than the native resolution, you're not getting any benefit from the extra resolution. In almost every case, extra pixels will not make a lower-resolution source look better. All other things being equal, the same DVD shown on EDTV plasma and an HDTV plasma will have the same amount of detail.

Here are some examples of how native resolutions interact with DVD and HDTV sources in the real world: 

 

32-inch analog TV
 
 

32-inch analog TV

42-inch EDTV plasma
 

42-inch EDTV plasma

42-inch HDTV plasma
 

42-inch HDTV plasma

50-inch or larger plasma; 23-inch or larger LCD; 720p DLP, LCD or LCoS rear-projection

DLP or LCD rear-projection

1080p flat-panel LCD; 1080p DLP or LCoS rear-projection

1080p flat-panel LCD

What is the native resolution?

No exact number, since it doesn't use pixels, but the amount of detail, for a good analog TV, would be the equivalent of 640x480 pixels.

852x480 pixels

1,024x768 or 1,024x1,024 pixels

1,280x720, 1,280x768, or 1,366x768 pixels

1,920x1,080 pixels

If you feed it an HDTV signal, will you see a picture?

No

Yes

Yes

Yes

Yes

Will it display every pixel of wide-screen DVD?

No

Yes

Yes

Yes

Yes

Will it display every pixel of 720p HDTV?

No

No

No

Yes

Yes

Will it display every pixel of 1080i HDTV?

No

No

No

No

Yes



When HDTV isn't all there
Currently, HDTV comes in two flavors: 1080i, used by CBS, NBC, HBO, and many others; and 720p, used only by ABC, ESPN, and Fox. As you can see, even the most expensive so-called HDTV plasmas can't deliver all of the detail of 1080i HDTV, which is why we use the word so-called. It should be noted, however, that HDTV sources still look highly detailed on these TVs and, frankly, even on EDTV plasmas.

1080p
There's another native resolution that's available in flat-panel LCDs and rear-projection microdisplays: 1080p. These sets have imaging elements with 1,920x1,080 pixels, which should allow them to display every single detail of 1080i high-def TV sources. We say should for a reason: the real onscreen resolution still might be less than all 2 million pixels, for a variety of reasons. With flat-panel LCDs, video processing can soften the visible resolution. With rear-projection microdisplays, the brightness-enhancing screen can also soften resolution, especially in models smaller than 60 inches diagonal. Whether or not these sets can handle every pixel, however, they provide the benefit of smaller, more closely packed pixels, meaning you can sit closer and not notice the pixel grid--the screen-door effect. And they definitely provide sharper pictures than 720p native-resolution sets, regardless of whether they actually resolve every detail of 1080i.

How much does pixel count matter?
If we go back to the example of the two otherwise identical plasmas above, the question remains: Is it worth another $1,000 to get the HDTV plasma, or is EDTV enough? Keep in mind the following:

  1. DVD and standard TV will look basically the same on both.
  2. EDTVs plasmas generally have better black-level performance and higher contrast ratios, which lead to better-looking dark scenes.
  3. HDTV plasmas will look significantly more detailed with HDTV and computer sources, even though they don't show every pixel.
  4. HDTV plasmas have smaller pixels, allowing you to sit closer without discerning the pixel grid.

Ultimately, the choice comes down to whether you believe the increased resolution with high-def or computer sources is worth the price difference and, in some cases, the trade-off in black-level performance. Keep in mind that TVs last a long time and that more and more HDTV is becoming available, so you'll have more opportunities to take advantage of extra pixels in the future.

Resolution isn't everything
Before you rush out and buy a plasma purely on the basis of its pixel count, remember that resolution is only part of the story. Performance among fixed-pixel displays still varies widely, and color accuracy, black levels, video processing, and the rest are all important factors in picture quality. What's really the best way to know which fixed-pixel TV to buy? Research your purchase using CNET's reviews, and ultimately, go into a store and see for yourself.