2. Advantages
 Allows a much bigger image.
 Wide viewing angle.
 Allows for Keystone correction (where the top of the image is
wider than the bottom of the image, see picture below).

3. Disadvantages
 The room lighting for front projection must be carefully designed.
The image you view, when front projection is used, consists of
light from the projector reflected off the screen. This also means
any light in the room will also be reflected off the screen back to
you, washing out the image (this is why a cinema is generally
very, very dark).
 Projection equipment is often located in the same room as the
screen and unless carefully coordinated creates a new source of
noise, glare, distraction, etc.

4. Advantages
 Allows for easy interaction with the projected image.
 Good for long, narrow rooms such as conference rooms.
 Can be viewed in a room with normal illumination.
 Excellent for taking notes and command center types of situations
where individuals move around and are doing other activities.
 Generally provides a cleaner looking system installation
appearance.

5. Disadvantages
 Screen size is limited to the size of transportable glass.
 Space is required behind the projection screen. However, this
space can be utilized as the audiovisual system equipment room.
The use of mirrors can further reduce the depth requirements of
the room.
 Rear projection systems are generally a little more expensive. Rear
projection screens are slightly more expensive than front
projection roll down screens and the additional cost of the square
footage required for the rear projection room can be an issue.

6. A CRT projector is a video projector that uses a small, high-
brightness CRT (or picture tube) as the image generating element. The
image is then focused and enlarged onto a screen using a lens kept in
front of the CRT face. Most modern CRT projectors are color and have
three separate CRTs (instead of a single, color CRT), and their own
lenses to achieve color images. The red, green and blue portions of the
incoming video signal are processed and sent to the respective CRTs
whose images are focused by their lenses to achieve the overall
picture on the screen. Various designs have made it to production,
including the "direct" CRT-lens design, and the Schmidt-CRT, which
employed a phosphor screen that illuminates a perforated spherical
mirror, all within an evacuated "tube.“

7. Advantages
 Long service life; CRT tubes maintain good brightness to 10,000
hours.
 High-end CRT projectors can precisely display images up to 1920
x 1200 with accurate color reproduction. A few projectors can
scan at even higher resolutions up to 3200 x 2560, although their
ability to resolve fine detail at this resolution is greatly reduced.
 Superior black level compared to LCD and DLP based projectors.
 As with CRT monitors, the image resolution and the refresh rate
are not fixed but variable within some limits. Interlaced material
can be played directly, without need for
imperfect deinterlacingmechanisms.
 Very fast response time (especially when compared to LCD-based
projectors), resulting in minimal (if any) motion blur when
showing video with fast motion.
 CRT projectors do not show a Rainbow effect seen with single
chip DLP projectors.

8. Disadvantages
 CRT projectors are both considerably larger and heavier than
comparable LCD and DLP projectors.
 CRT projectors require far more time to set up and adjust than
LCD and DLP based projectors.
 Absolute ANSI brightness achievable with CRT projectors is lower
than with comparable LCD and DLP projectors.
 Low-end or poorly tuned CRT projectors may suffer from color
divergence or geometric distortion (for example, straight lines
may not always appear completely straight, especially near the
corners).
 CRT projectors use more power / cost more to run than LCD and
DLP units.
 Unlike LCD or DLP projectors, CRT projectors are somewhat
prone to burn-in. This can lead to issues in brightness uniformity
on projectors that frequently use both a full 4:3 and widescreen
aspect ratio.

9. An LCD projector is a type of video projector for
displaying video, images or computer data on a screen or
other flat surface. It is a modern equivalent of the slide
projector or overhead projector. To display images, LCD
(liquid-crystal display) projectors typically send light from
a metal-halide lamp through a prism or series of dichroic
filters that separates light to three polysilicon panels – one
each for the red, green and blue components of the video
signal. As polarized light passes through the panels
(combination of polarizer, LCD panel and analyzer),
individual pixels can be opened to allow light to pass or
closed to block the light. The combination of open and
closed pixels can produce a wide range of colors and
shades in the projected image.

10.  LED projectors are becoming more and more popular.
LED technology is used in a wide range of
products, including home theater projectors, business
and education projectors, and even the emerging
market of pico projectors, handheld projectors, and
other mini projector systems.
 LED light sources have some serious advantages over
conventional lamps. LED projectors require little
maintenance, as there is no lamp to be changed.
Furthermore, LED light sources last significantly
longer than the competition. Lastly, the techonology is
greener than the alternative conventional projector
lamps. Between their long lives, lack of upkeep, and
lower power usage, LED projectors save you money in
the long run.