- In this report
- Overview
- CR Quick Recommendations: LCD TVs
- CR Quick Recommendations: Plasma TVs
- Ratings: LCD TVs
- Ratings: Plasma TVs
- Types
- HDMI
- HD formats
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November 2006
Deciphering 1080p & other HD formats
The numbers game in HDTV is getting ever more challenging. As if “1080i” and “720p” weren’t confusing enough, along comes
“1080p,” this season’s advertising term of choice. Here’s a simple--well, relatively simple--guide to these terms, which refer
to three different HD formats.
The numbers indicate lines of data; the letters, how the data are delivered. The 1080 and 720 refer to the number of horizontal lines of video data in an HD signal. (A standard-definition signal, by contrast, has 480 lines of horizontal data.) “P” refers to progressive-scan; all pixels in a frame of video are sent in one sweep. “I” stands for interlaced; a field with half the pixels arrives first, followed by another with the rest of the pixels a fraction of a second later. A viewer perceives them as one frame.
Progressive images should look smoother. Because an interlaced signal contains two fields of video captured at different times, some TVs will display “jaggies” on the edges of moving objects. A progressive signal should look smoother because all pixels in a frame were captured at the same time and sent consecutively.
Incoming HD signals are often converted to match a TV’s native resolution. Flat-panel TVs have a set number of pixels. A TV with a native resolution of 1366x768 can’t display anything with more than 768 lines (the second number is the key). When such a TV receives 1080i signals, it downconverts them, but picture quality can be excellent if the TV does its job well.
1080p TVs can display more detail, but some can’t accept a 1080p signal. TVs with 1920x1080 resolution are the only screens with enough pixels to display every detail in a 1080i signal or the high-def DVD output from a Blu-ray or HD DVD player. Oddly, some 1080p TVs can’t accept 1080p signals from high-def players. That’s not a big concern. A player can output 1080i signals, which the TV will convert to 1080p. The picture quality can be excellent, especially with film-based movies and TV shows. Most viewers would find it hard to distinguish between converted 1080i and true 1080p.
The numbers indicate lines of data; the letters, how the data are delivered. The 1080 and 720 refer to the number of horizontal lines of video data in an HD signal. (A standard-definition signal, by contrast, has 480 lines of horizontal data.) “P” refers to progressive-scan; all pixels in a frame of video are sent in one sweep. “I” stands for interlaced; a field with half the pixels arrives first, followed by another with the rest of the pixels a fraction of a second later. A viewer perceives them as one frame.
Progressive images should look smoother. Because an interlaced signal contains two fields of video captured at different times, some TVs will display “jaggies” on the edges of moving objects. A progressive signal should look smoother because all pixels in a frame were captured at the same time and sent consecutively.
Incoming HD signals are often converted to match a TV’s native resolution. Flat-panel TVs have a set number of pixels. A TV with a native resolution of 1366x768 can’t display anything with more than 768 lines (the second number is the key). When such a TV receives 1080i signals, it downconverts them, but picture quality can be excellent if the TV does its job well.
1080p TVs can display more detail, but some can’t accept a 1080p signal. TVs with 1920x1080 resolution are the only screens with enough pixels to display every detail in a 1080i signal or the high-def DVD output from a Blu-ray or HD DVD player. Oddly, some 1080p TVs can’t accept 1080p signals from high-def players. That’s not a big concern. A player can output 1080i signals, which the TV will convert to 1080p. The picture quality can be excellent, especially with film-based movies and TV shows. Most viewers would find it hard to distinguish between converted 1080i and true 1080p.
