Picture Formats - Cisco CHS 435HDC Installation Manual

Picture Formats

What Is the Difference Between a Standard-Screen and a
Wide-Screen HDTV?
The type of screen your HDTV has (wide-screen or standard-screen) determines how the
set-top displays programs on the screen. The picture format for an HDTV is a combination
of aspect ratio and screen resolution and is different for standard-screen and wide-screen
HDTVs.
What Is Aspect Ratio?
An aspect ratio is the ratio of the width to the height of the TV screen. The aspect ratios
differ because the television industry manufactures both standard-screen and wide-screen
HDTVs to appeal to consumer viewing preferences.
What Is the Screen Resolution?
The screen resolution indicates the amount of detail that the picture displays. Resolution is
identifi ed by the number of display lines on the screen. The techniques that an HDTV uses
to "paint" the picture on the screen are referred to as progressive and interlaced.
With the progressive scanning method, the lines are drawn on the screen one at a time
in sequential order. Progressive scanning results in a more detailed image on the screen
and is also less susceptible to the fl icker commonly associated with interlaced scanning. The
interlaced method involves refreshing pixels in alternation — fi rst the odd lines and then
the even lines.
For advanced setup, select the screen resolution that your TV can support. Refer to your
HDTV user manuals to choose the proper screen resolution (480i, 720p, 1080i) for your
setup.
For example, a screen resolution of 1080i indicates that the screen shows 1080 lines in an
interlaced display, and 720p indicates that the screens shows 720 lines in a progressive
display.
A standard-screen HDTV has a 4x3
aspect ratio. The screen is 4 units wide
for every 3 units tall.
3
A screen resolution of 480i fi lls the
screen.
30
4
A wide-screen HDTV is one-third wider
than a standard-screen HDTV. The screen
is 16 units wide for every 9 units tall.
9
A screen resolution of 720p or 1080i fi lls
the screen.
16