HDTV: Know your high-res options
04/16/2007Show another tip
By CNET Online Courses, CNET Editor
Level: All
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Resolution, or picture detail, is the main reason why HDTV programs look so good. The standard-definition programming most of us watch today has at most 480 visible lines of detail, whereas HDTV has as many as 1,080. HDTV looks sharper and clearer than regular TV by a wide margin, especially on big-screen televisions.
High definition actually comes in two different resolutions, called 1080i and 720p. One is not necessarily better than the other; 1080i has more lines and pixels, but 720p is a progressive-scan format that should deliver a smoother image that stays sharper during motion.
Another format is also becoming more well-known: 1080p, which combines the superior resolution of 1080i with the progressive-scan smoothness of 720p. True 1080p content is extremely scarce however, and none of the major networks have announced 1080p broadcasts. Check out our comparison chart below to see how HDTV stacks up against standard TV and progressive-scan DVD.
| Name | Resolution | HDTV? | Wide- screen? | Progressive- scan? |
|---|---|---|---|---|
| 1080p | 1,920×1,080 | Y | Y | Y |
| 1080i | 1,920×1,080 | Y | Y | N |
| 720p | 1,280×720 | Y | Y | Y |
| Wide-screen 480p (DVD, EDTV) | 852×480 | N | Y | Y |
| Regular TV | Up to 480 lines | N | N | N |
1080i vs. 720p broadcasts — the main contenders
True HDTV programming is typically broadcast in one of two resolutions: 1080i or 720p. Most networks have opted for the 1080i format, boasting that it provides the highest possible resolution, while ABC, Fox, ESPN/ESPN2, and the National Geographic Channel went for the smoother pictures of 720p.
What’s the real difference between the two? While 1080i technically offers the most lines of resolution, it’s delivered in the old-style interlaced format, meaning that your TV set draws each frame in two passes: once for the even horizontal lines and a second time for the odd lines. The 720p (progressive) format has fewer lines of information than 1080i but draws each frame in a single pass, delivering pictures that look slightly smoother than an interlaced image, especially when there’s a lot of movement on the screen. Most videophiles agree that 720p is the superior format, despite 1080i’s resolution advantage. For average viewers, however, it’s hard to tell the difference.
The information in this tip originally appeared in the HDTV 101 online class.
Tags: HDTV , HDTV resolution
