A Progressive Scan converter takes an Interlaced Scan
formatted signal, and converts it to a superior signal
where the complete picture is drawn from top to bottom
in one pass. This results in less flicker and smoother
Most TV signals are sent in an "Interlaced Scan"
format. First the display device (TV or projector)
displays the image's odd lines, one at a time from top
to bottom. This takes about one sixtieth of a second. It
then fills in the even lines, taking another one
sixtieth of a second. So the full picture is first drawn
with half its information missing, which is then filled
in. In all the process takes 1/30 of a second per
Some DVD players have progressive scan converters
built in, and may have the option to output in either
progressive or interlaced scan modes. Some projectors
(in particular the specialist home cinema projectors)
also have progressive scan converters built in.
Alternatively, it is possible to purchase an inexpensive
progressive scan converter as a separate unit which can
convert your TV and DVD signals.
Multiple Computer Ports
If you want to connect multiple
computers or video sources to the projector
simultaneously, you will need multiple input jacks to
accommodate this. For example, you may want to connect a
notebook computer and a desktop computer to support two
consecutive presentations, or two different presenters.
If your projector only has one computer source, you'll
have to unplug the notebook and plug in the desktop
between presentations. Check to make sure the projector
has enough connections to support your typical use.
Video Signal Standards:
Most business projectors accept
composite video, S-video, and computer/RGB signals as
three types of signal transmission.
Most projectors also recognize YPbPr/YCbCr
component video as well. However, there are two
all-digital standards known as DVI and HDMI. Many new
computer video cards feature DVI or HDMI output, which
allow the user to keep the signal in the digital domain
and eliminate analog to digital conversions.
If you are interested in optimizing
video performance and you have a video source that
offers DVI or HDMI output, check to see which of the
projectors on your list possess a digital input. The
spec sheet may say HDMI, DVI-I, or DVI-D.
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