What's the Difference between "Standard Def" and "High Def"?

Written by Clearly Resolved
Sunday, 20 May 2007

[ Q ] What's the difference between HDTV and "standard definition" TV?

[ A ] Standard definition is a catch-all term that is commonly used to refer to programming that was created to be compatible with various color television system standards that have been in place around the world for the past 40 or 50 years. While the exact specifications for these standard-definition broadcast TV systems vary by region or country, in general they provided something on the order of 500 to 600 lines of vertical resolution, with a total picture element (pixel) count ranging between 250,000 to 400,000 pixels.

There are a number of high-definition formats in use today, but the general rule of thumb is that for a format to qualify as "hi def," the total pixel count needs to be near or in excess of 1 million pixels.

At the moment, there are basically just three HDTV formats used in the US and in other parts of the world -- the 1080p format, the 1080i format and the 720p format.

The 1,080-line formats make use of video frames containing 1,080 lines of vertical resolution and 1,920 lines of horizontal resolution for a maximum pixel count in excess of 2 million. The difference between 1080i and 1080p is the difference between "interlaced" and "progressive" video. With 1080-line progressive video (1080p), all of the 2 million-plus pixels (1,080 x 1920) are displayed at the same time; in the 1080-line interlaced format (1080i), the maximum number of pixels displayed at any point in time is just half the total for 1080p (540 x 1,920).

The other popular HD format, 720p, is the product of 720 lines of vertical resolution and 1,280 lines of horizontal resolution, making for a total of 921,600 pixels. Because 720p is a progressive video format, all 921,600 pixels are displayed on the screen at the same time.

100,00% of 4 voters found this FAQ useful, I found this FAQ

useful

not useful

< Prev		Next >