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Wednesday, October 1, 2008

HDTV FAQs

By Nilesh Parab

Bombarded with numbers like 1080p, 1080i, 720p, etc., but confused as to their exact meaning? Not sure which HDTV resolution you should go for? Curious about what HDTV "display" and "source" resolutions are? Then you have come to the right place. Here, you will find clear and concise information about these terms and concepts.

What is Resolution? A Digital Television screen is made up of a grid of dots (called pixels), which light up in different colors to make up the picture which you see on the screen.The number of pixels arranged in each horizontal line is called the Horizontal Resolution of the screen.

The number of pixels in each vertical line is called the Vertical Resolution of the screen. The combined horizontal and vertical resolutions are stated as the Display Resolution or Screen Resolution. For example, if there are 200 pixels in one horizontal line, and 100 pixels in each vertical line, then the horizontal resolution is 200 pixels, and the vertical resolution is 100 pixels. And the Display Resolution or Screen Resolution is written as 200 x 100 pixels. More pixels crammed together in each horizontal and vertical line make higher resolution (or higher definition). Higher resolution makes the picture sharper.What is Scanning? Scanning is the method with which pictures are drawn on the digital television screen. There are two methods of scanning:

- Progressive Scanning (p) - A method of displaying pictures by drawing horizontal lines sequentially.

- Interlaced Scanning (i) - A method of displaying pictures by drawing odd lines first and then the even lines. eg, lines no. 1,3,5...199 are drawn first, and lines no. 2,4,6...200 are drawn afterwards.

Progressive scan gives better picture quality than interlaced scanning.
It has become common to refer to the Display Resolution by quoting only the vertical resolution followed by the scanning mode letter. eg. 100i means a display with vertical resolution 100 pixels and interlaced scanning mode.

What is HDTV?

HDTV stands for High Definition Television, which is a system whose pictures have vertical resolution greater than 720 pixels. It is implemented by a combination of the following:

- HDTV Sources providing high definition content (eg, TV Channels broadcasting high definition pictures, BluRay DVDs containing high definition pictures, etc) and

- HDTV Displays (HDTV Television Sets) which show those high definition pictures coming from HDTV Sources.

HDTV Display Resolutions

The most common HDTV Display Resolutions found today are:

- 1080p - Displays with vertical resolution 1080 pixels and progressive scanning.

- 1080i - Displays with vertical resolution 1080 pixels and interlaced scanning.

- 720p - Displays with vertical resolution 720 pixels and progressive scanning.

Which is better?

In general terms, the higher the resolution - the better is the picture quality, and progressive scanning is better than interlaced scanning for moving images. So, obviously, 1080p is the best. But even 720p suffices for viewing broadcast television channels, as these are limited to 720p content sources. The real advantage of a 1080p is when you are viewing Bluray Discs, and HD DVD which are 1080p sources.

As with other stuff, your needs dictate what you should buy.

 

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