DLP, digital light processing
DLP, Digital Light Processing, is a relative new technology that uses a digital mirror, composed of
millions of small moveable mirrors, to project the image. Each mirror can either be switched on, and
projects a ray of light through the lens, or off, which will not result in any light entering the lens. The
actual image is formed on the mirror and reflected off of it through the projection lens onto the screen.
Color is added in a DLP projector by using a rotating color wheel with the three primary colors, red, blue
and green, in front of the mirror and then combining the images for these three colors faster than the
human eye can see. Obviously with these three primary colors every possible color can be displayed,
simply by switching the mirrors on and off at a higher or lower frequency in synchronization with the color
wheel. A brighter red simply means that during the time that the red segment of the color wheel is in
front of the mirror, the mirrors are more on than off and more of the red light is projected through the lens.
The basic construction of a DLP projector isn’t that different from a LCD projector, with the biggest
difference being the fact that we’re projecting onto a mirror instead of through a number of LCD displays.
Again we see the use of a high pressure gas-discharge lamp as a light source. The light from the lamp
shines through the rotating color wheel and the colored light is then projected onto the digital mirror and
the image on the mirror is synchronized with the color wheel so the image is displayed properly. One of
the advantages of using a rotating colorwheel is that often also a transparent segment is used which
greatly enhances contrast, as white light is not created by combining the three primary colors, but by
simply synchronizing the transparent segment. A downside of using the colorwheel obviously is the fact
that not all colors can be displayed simultaneously; only one color can be displayed at any given time.
That also is a disadvantage of a DLP projector as the rapid switching between colors cause for some
people to see ‘rainbows’ across white text or white objects in movies. This is simply caused by the
rotation of the colorwheel and may, or may not, be noticeable. During our testing we found that these
effects wear off over time if we even noticed them.
A well documented advantage of a DLP projector is a reduction of the screendoor effect, about 90% of
the surface area of each mirror is used for projecting the image, and thus the effective pixel area is
much larger. Another advantage is the high contrast ratio; most DLP projectors have a 2000:1 contrast
ratio, which is much higher than most LCD projectors which, on average, have a 500:1 contrast ratio.
The projected image therefore has blacker blacks and whiter whites in comparison to an LCD projector.
Another optical advantage is the fact that the path the light has to travel in the projector is much shorter in
a DLP projector. A DLP projector is pretty straightforward and the only object in between the image on
the digital mirror and the projection screen is the projector’ lens. This obviously has a positive effect on
color balance and reproduction as well as being a more elegant solution overall.
Welcome to the
Projection format - Aspect Ratio
Wide Screen TV Information
by High-Tech Productions / Blank Video Tape.com. Full article available at
Wide Screen (or "Letterbox") is a way of watching a movie on your TV as the movie was originally shown in the theaters. A
normal television has a screen ratio of 4:3 also called 1.33:1. This means that the TV is 1.33 times wider than it is high.
Most movies are filmed in a format where they were shown in ratios of 1.66:1 all the way up to 3:1 where the movie was
three times as wide as it is high. Unfortunately, because TV screens are not that wide, we have been subjected to movies
having visual portions completely cut off so that the image will fit on our screens.
This is where wide screen videos and DVDs come into play. The wide screen transfer process actually shrinks a movie
down so that the entire visual image fits on your television screen. This results in what are inaccurately called "black bars".
Please read the rest of the article. It will help you understand terms such as 4:3 native or Video format, and 16:9 native or
HDTV format. You will understand what type of screen you need and why.
Satellite Video Source
The most important element of the full Home Theater experience, is the video signal source. It must be a
digital signal. DVDs are both digital and HDTV. Satellite dish services are digital and some programming is
HDTV. If your local TV cable service does not provide digital video services, or you have no access to a TV
cable, there is no choice but to subscribe to a satellite dish service. There are only two major services
available: Dish Networks / Echostar Communications and Direct TV.
Now you can get your movies below.
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