EDTV

EDTV

Enhanced definition television (EDTV) is the least known quality of digital television. EDTV has been made popular by FOX networks that broadcasts in EDTV instead of HDTV or SDTV (FOX plans to convert to HDTV in 2005). EDTV is about equivalent to the quality that you usually get from DVDs.

Here's a quick comparison of the differences. Of course these images would be stretched across the television screen, but this shows the images with equal sized pixels.

CDTV is more commonly known as NTSC. It's the basic signal that was defined in 1953! Over 50 years old and its still going strong. How's that for some technology ahead of its time.

Standard Definition Television (SDTV)

640 X 480

480 scan lines with about 640 horizontal pixels in a 4:3 aspect ratio.

SDTV is your basic digital format that is pretty darn good when it's not compressed to death. The basic 640 x 480 spatial resolution is often quoted but rarely met because cable and satellite companies compress the quality of the images to below CDTV. They do this to fit more channels in a given bandwidth. They compromise quality to deliver quantity (more stations for the given bandwidth).

EDTV is usually broadcast at higher data rates to yield much higher quality than SDTV. Although only 64 more pixels should be in each scan line, the compression is usually not squeezed so much so that you can see many more horizontal pixels. One of the main differences with EDTV is that it is often broadcast in 16:9 aspect ratio instead of the 4:3 aspect ratio. There are 16

Enhanced Definition Television 4:3

704 X 480

480 scan lines with 704 horizontal pixels in a 4:3 aspect ratio.

Enhanced Definition Television 16:9

704 X 480

480 scan lines with 704 horizontal pixels in a 16:9 aspect ratio. Notice the red flag and the full sign in this view.

The difference between EDTV in the 4:3 and the 16:9 aspect ratio is the final display size of the pixels. Since the same number of pixels are displayed in each format, the 16:9 pixels need to be stretched horizontally to fill the wider screen. To display the 4:3 image on a wide screen HDTV, the image will need to be distorted or cropped. The 16:9 aspect ratio EDTV will stretch to the wide screen.

DVD

720 X 480

480 scan lines with 720 horizontal pixels in a 4:3 or 16:9 aspect ratio. A 4:3 aspect ratio is shown. You'd have a difficult time telling the difference between and DVD and EDTV.

The DVD image will provide up to 16 more horizontal pixels in each scan line. You probably won't be able to tell the difference between EDTV that was not compressed much to DVDs. DVDs can be sent in either aspect ratio or even the films original aspect ratio that might be even higher than the 1.78 aspect ratio of 16:9.

TV
DTV
CDTV
SDTV
EDTV
HDTV - Spatial Resolution - Temporal Resolution - Aspect Ratio
Video Quality
Television is a very complex topic. If you would like to add some comments, corrections or additional topics, please e-mail info@broadent.com.