What’s the Big Deal About High Definition?
The first thing that you need to know about High Definition TV (HDTV) is that the number of pixels used to make up the
image that you see is greatly increased. Pixels are the small dots that make up the image on a TV or computer screen. A
standard definition image is 640 x 480 pixels. A HDTV image can have as many as six times as many pixels!
Below is an image that illustrates these basic differences in image resolution.
The first thing that you need to know about High Definition TV (HDTV) is that the number of pixels used to make up the
image that you see is greatly increased. Pixels are the small dots that make up the image on a TV or computer screen. A
standard definition image is 640 x 480 pixels. A HDTV image can have as many as six times as many pixels!
Below is an image that illustrates these basic differences in image resolution.
The second major difference has to do with the way an image is created on the screen. Up until the birth of personal
computers, images on a screen were created using an interlaced pattern. Interlacing is the process of first showing the odd
lines and then showing the even number of lines. Each of these sets of lines is called a field, and it takes both to make one
frame of an image. Interlacing can result in an image that has a somewhat better resolution; however, it can also introduce
flicker and distortion into the image.
Progressive scan shows each line in order, rather than skipping lines and coming back to complete the image. Progressive
scan generally has a higher perceived vertical resolution, as well as the added benefit of reducing flicker. The electronics
that are used to process a progressive scan image are generally a bit simpler as well.
computers, images on a screen were created using an interlaced pattern. Interlacing is the process of first showing the odd
lines and then showing the even number of lines. Each of these sets of lines is called a field, and it takes both to make one
frame of an image. Interlacing can result in an image that has a somewhat better resolution; however, it can also introduce
flicker and distortion into the image.
Progressive scan shows each line in order, rather than skipping lines and coming back to complete the image. Progressive
scan generally has a higher perceived vertical resolution, as well as the added benefit of reducing flicker. The electronics
that are used to process a progressive scan image are generally a bit simpler as well.
| Interlaced Odd Field |
| Interlaced Even Field |
| Progressive Frame |
The electronics industry has come up with a shorthand to differentiate between the types of images that are displayed.
There is a number representing the number of lines that are in an image followed by a letter to indicate if the image is
progressive or interlaced. 480i is the old television signal while 720p and 1080i are the HDTV broadcast standards. A 1080p
signal is generally only available through a BluRay player.
There is a number representing the number of lines that are in an image followed by a letter to indicate if the image is
progressive or interlaced. 480i is the old television signal while 720p and 1080i are the HDTV broadcast standards. A 1080p
signal is generally only available through a BluRay player.
 |  |  |  |  |  |  |  |
