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Education | Video Formats
VGA Format Max. Resolution
VGA (Video Graphics Array) 640 x 480
SVGA (Super Video Graphics Array) 800 x 600
XGA (Extended Graphics Array) 1024 x 768
W-XGA (Wide Extended Graphics Array) 1366 x 768
SXGA (Super Extended Graphics Array) 1280 x 1024
UXGA (Ultra Extended Graphics Array) 1600 x 1200
WUXGA (Wide Ultra Extended Graphics Array) 1920 x 1200
ost analog formats were designed primarily for broadcast
TV transmissions, so they limit the transmission bandwidth
required for the signal. The video is typically formatted
by combining TV signals into a lower-bandwidth encoded
signal. But other analog formats, such as VGA, were
designed primarily
for computer graphics, so they’re far less restricted in bandwidth
and, therefore, keep the red, green, and blue signals separate to allow
higher-resolution pictures that are suitable for viewing from short
distances. Here’s a comparison of the various formats:
Composite video
Among the connector formats designed originally for TV,
Composite video is the analog TV signal before modulation
onto an RF carrier. It‘s the standard that connects most older
consumer video equipment, including VCRs, CCTV cameras, and video
CD players.
As its name suggests, Composite video has the luminance (black and
white), chrominance (color) and sync pulses combined in one signal.
When developed, Composite video was designed to work with both
color and black-and-white TV signals. This backwards compatibility
ensured a smooth transition between the two formats in the 1950s.
Black-and-white TV sets were able to ignore the color component while
newer sets separated it
out and displayed it with the luminance information.
Although this format solved the problem of backward compatibility
at the time, by today’s standards, Composite video doesn’t project a very
sharp picture. Because all the video components are transmitted
together, they can interact with each other and cause picture defects like
dot crawl and color smear.
S-Video
Also often called Y/C video, S-Video was introduced in the
1980s to overcome some of the shortfalls associated with
Composite video. It’s a less encoded video format. In the
S-Video signal,
color (C) and luminance (Y) information are transmitted separately to
produce a sharper picture image on the display device.
Most video equipment with an S-Video connector typically also has
a Composite connector. When connecting devices that support both
interfaces, it’s best to use the S-Video connector.
Component video
Next up the resolution scale from S-Video is Component
video (YCbCr). It separates the signal to an even greater
extent than S-Video, further reducing the chance of
interference and, as a result, improving picture quality. It
provides images with higher resolution and better color
quality than either traditional Composite video or S-Video.
Component video separates color information into two color
difference signals: B-Y (blue minus luminance, also called Cb
or Pb) and R-Y (red minus luminance, also called Cr or Pr).
These along with Y (luminance) result in a total of three
signals.
You can find Component video on a lot of DVD players, TV receivers, and
other AV equipment, displaying the video of DVDs to their best
advantage. Until a few years ago, many video devices typically had all
three sets of connectors, with the Component video format
communicated via either three BNC connectors (typically the case on
higher-end, professional AV equipment) or RCA connectors (consumer-
grade electronics).
But today, you might find only a Component connection along with a
digital video connector. This way, your TV can make use of the full range
of video signals.
RCA Component
VGA video
Composite, S-Video, and Component were designed primarily as TV
formats. However, when discussing analog computer video formats, we’re
usually talking about variations of the VGA (Video Graphics Array) format.
The VGA interface carries analog RGB with separate horizontal and
vertical sync signals and is presented on an HD15 connector (also called
15-pin D-subminiature). When VGA was introduced by IBM
®
in 1987 for
PC video display, it was a huge improvement over the earlier EGA DB9
connector. VGA, the basic format, supports resolutions up to 640 x 480
with 256 colors.
SVGA (Super VGA), XGA, and later formats continued the drive to
provide ever-sharper images and greater color depth (see the chart
below)—oftentimes, rivaling those of digital 1080i and 1080p displays.
Plus, over the years, VESA standards have brought interoperability to a
market that was becoming a mixture of often incompatible SVGA
graphics cards.
Analog Video Formats
M
BNC Component
Standard Monitor Widescreen 1680x1050
Standard Monitor 1600x1200
Display standards are a combination of display resolution (specified as the width and
height in pixels), color depth (measured in bits), and refresh rate (expressed in hertz).
Widescreen 16:10 TV 3:2 HDTV 16:9 Monitor 4:3
Video aspect ratios and resolutions