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12 ViewSonic VPW505
RUNNING HDTV
Understanding HDTV
What is Digital Television or DTV?
Digital TVs are televisions that can receive and display digital television broadcasts sent using any one of
three following categories: HDTV (High Definition TV), EDTV (Enhanced Digital TV), and SDTV (Standard
Definition TV).
What is the Difference Between HDTV, EDTV, and SDTV?
HDTV, EDTV, and SDTV are three grades of televison or displays. They reference the maximum resolution
capability of a digital television or display to fully display digital broadcasts without having to “down-con-
vert” the actual signal content to fit the display’s display limitations. The resolution requirements for each of
the three DTV classifications and an explanation of the specifications are described below:
Vertical Res.
1
Horizontal Res.
2
Aspect Ratio
3
Scan Method
4
1080 lines 1920 dots 16:9 Wide Interlaced
720 lines 1280 dots 16:9 Wide Progressive
HDTV grade televisions and displays are capable of displaying a maximum of either 1080
lines using interlaced scan method or 720 lines using progressive scan method.
Vertical Res.
1
Horizontal Res.
2
Aspect Ratio
3
Scan Method
4
480 lines 640 dots 4:3 Progressive
EDTV grade televisions and displays are capable of displaying a maximum of 480 lines
using progressive scan method. All resolutions higher than 480 lines must be reduced to
480 lines in order to be displayed. Progressive scan method reduces flicker; however, pic-
ture quality may not necessarily outperform 480 interlaced when viewed at normal view-
ing distances.
Vertical Res.
1
Horizontal Res.
2
Aspect Ratio
3
Scan Method
4
480 lines 640 dots 4:3 Interlaced
SDTV grade televisions and displays are capable of displaying a maximum of 480 lines
using interlaced scan method. All resolutions higher than 480 lines must be reduced to
480 lines in order to be displayed.
1
Vertical Resolution (Scan Lines)
Vertical scan lines refer to the number of horizontal lines a TV or display can display to create an image. As
the number of lines increase, more information is displayed, resulting in better picture quality.
2
Horizontal Resolution
Each horizontal line in a TV or display is made up of individual dots (pixels). The higher the number of pixels,
the finer the TV picture becomes. Horizontal pixel measurements using today's technology can range from
250 for a VCR to as much as 500 for a DVD player.
3
Aspect Ratio
Aspect ratio identifies the ratio of the TV screen's width over its height. A 16:9 aspect ratio refers to a wide-
screen picture format, while a 4:3 refers to a standard “square” TV format.
4
Scan Mode
Interlaced scanning is a method that creates a TV picture with alternating lines of information and is the cause
for flickering. Progressive scanning is a method that creates a TV picture with consecutive lines of informa-
tion that results in flicker-free picture quality.