HDTV Resolutions: What You Need to Know

480p: This is the typical resolution of regular DVDs, Xbox/PlayStation 2/GameCube/Wii games, and standard digital cable. It has 480 lines of resolution. The "p" stands for "progressive," which means that the lines that make up a picture are scanned one after the other from top to bottom (but, of course, so fast that the eye can't even begin to notice). 480p is also the highest resolution (in other words, not HD) found on bargain-priced EDTV plasmas you may have seen at Costco and the like.

720p: The minimum resolution that is considered high-definition (HD), 720p is found in most Xbox 360 and PlayStation 2 games, some on-demand HD programming, and some over-the-air, cable, or satellite broadcasts. 720p uses the same progressive scanning method as 480p, but with 720 lines of resolution rather than 480. This adds greater clarity and detail to an image, particularly at larger screen sizes, and is typically the highest resolution found on more affordable HDTVs. 720p is best for sports, action, and anything that's fast-moving on the screen, which is maybe why ESPN and ABC broadcast in 720p signals.

1080i: This uses 1,080 lines to display an image, but the lines are interlaced, which means even-numbered lines are first scanned, followed by odd-numbered lines. It happens so fast, though, that the human eye doesn't notice. It's mainly a relic of old CRT televisions—flat-panel TVs actually de-interlace a 1080i signal, which gives something closer to a 1080p signal anyway (even though it'll say 1080i on your TV). From more than eight inches, most 1080i images will look the same as 1080p. For many videophiles, 1080i is considered better than 720p for movies, because you get more detail (it's less preferable for sports because fast action can get a bit blurred with 1080i).

1080p: The mother of all resolutions—or is it? Essentially, 1080p is simply the progressive version of 1080i (and since 1080i is de-interlaced on most flat-panel TVs, it's arguably a form of 1080p anyway). Since so few signals are actually in 1080p, it's not an essential feature at the moment. But the extra detail does help in situations where you have a big TV in a small room—the 1080p signals I've viewed don't let me see any pixels as close as seven feet away. If you've got a decent viewing distance, though, you'll be fine with TVs capable of showing 720p and 1080i signals. Only Blu-ray discs, HD-DVD discs, and some PS3 games output 1080p signals right now.

Generally, I've been steering people who ask me toward TVs that are capable of doing 1080p natively. But so many other factors, from viewing distance and connections to a TV's contrast ratio and video-processing capability, can influence the overall picture.

In the end, do you like the picture you see is the only question you have to ask yourself. If you can't see the pixels on the screen, then you probably don't need more resolution.

As I've mentioned in the past, the only spec you need regarding resolutions is a minimum of 720p—without that, you can't have HD. And for the best picture, make sure that you use at least component or HDMI connections.

Related links:

HDTV Buying Basics

For Dummies: Making Sense of the HDTV Marketing Mumbo-Jumbo

Battle of Giants: Consumer Reports' Top Plasma TVs

Consumer Reports' Top-Rated Projection TVs