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What is the Difference Between a Standard Screen and a Wide Screen
The type of screen your HDTV has (wide screen or standard screen) determines how programs are displayed on the screen. The picture format for an HDTV is a combination of aspect ratio and screen resolution and is different for standard-screen and wide-screen HDTVs.
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What is Aspect Ratio?
An aspect ratio is the ratio of the width to the height of the TV screen. The aspect ratios differ because the television industry manufactures both standard-screen and wide-screen HDTVs to appeal to consumer viewing preferences.
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A standard-screen HDTV has a 4:3 aspect ratio. The screen is 4 units wide for every 3 units tall.
A screen resolution of 480p or 480i fills the screen.
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A wide-screen HDTV has a 16:9 aspect ratio. The screen is 16 units wide for every 9 units tall.
A screen resolution of 720p or higher fills the screen.
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What is the Screen Resolution?
The screen resolution indicates the amount of detail that the picture displays. Resolution is identified by the number of display lines on the screen. The techniques that an HDTV uses to “paint” the picture on the screen are referred to as progressive and interlaced.
For example, a resolution of 1080i indicates that the screen shows 1080 lines in an interlaced display, and 480p indicates that the screens shows 480 lines in a progressive display.
Note: The screen resolution (1080i, 480p, and so forth) is sometimes referred to as the scan rate. The terms are interchangeable.
With the progressive method, every pixel on the screen is refreshed simultaneously. The interlace method involves refreshing pixels in alternation- first the odd lines and then the even lines.
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What are Picture Effects?
There are two methods stations broadcast HD signal that can result in three picture effects on your TV.
Centercut
One of two methods a station broadcasts high definition content, and switches program sources and commercials between high definition, and standard definition, content. This fills the 16:9 screen of an HDTV, the cable processing equipment acquires the content displayed with a 4:3 ratio section for analog output.
- The result: Analog televisions have little change in their picture, some lost content on the sides, but a full display on the television screens
- Stations decide how process their transmission
Letterbox
One of two methods a station broadcasts high definition content, and switches program sources and commercials between high definition, and standard definition, content.
When a station is broadcasting high definition content, again filling the 16:9 screen of a HDTV, the cable processing equipment acquires the entire 16:9 content to be used for analog output.
- The result: Analog television displays the rectangular picture and black bars appear on the top and bottom to fill the screen.
- The “letterbox” election causes most concerns and complaints.
- Stations decide how process their transmission
Postage Stamp
The “Postage Stamp” or black bars on all four sides, result when the down-conversion of a high definition broadcast is enabled for “letterbox” processing and the program content changes from a 16:9 HD to 4:3 SD program or commercial.
- Result: A smaller picture display flanked with black bars.
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