Aspect Ratio
Describes width of a picture to the height. The NTSC standard is 4:3. The current HDTV standard is 16:9. Modern movies range from 1.66:1 to 2.4:1. By far the most common are 1.85:1 and 2.35:1.
Contrast Ratio
The contrast ratio is a figure used to measure the luminance difference between the brightest white and the darkest black.
CRT Projector ( Cathode Ray Tube)
Consists of three tubes each putting out one color: red, green, and blue. They offer brightness and detail, but are difficult to setup, and convergence is required about two times a year. Used in TV and computer monitors.
DLP (Digital Light Processor)
Digital Light Processing generates images by reflecting light off the surface of a digital micro mirror device (DMD) containing hundreds of thousands of tiny mirrors, then through a color wheel and a lens and onto the screen. Higher resolution projectors have more mirrors in their DMD's-reflecting a greater amount of light for brighter images.
Dolby AC-3
The old name for the most popular 5.1-channel home theatre sound system. Now called Dolby Digital. Consists of: front left/right speakers, a center speaker, left/right surrounds, and a Low Frequency Effects (LFE) channel, usually used with a subwoofer.
Dolby Digital
1 - The new name for the most popular 5.1-channel home theater sound system. Used to be called Dolby AC-3. Consists of front left/right speakers, a center speaker, left/right surrounds, and a L ow F requency E ffects (LFE) channel, usually used with a subwoofer.
2 - A 5.1-channel sound system. Used in some commercial movie theaters in which the sound is placed in between the sprockets on the film.
Dolby Pro-Logic
Most popular surround format. Almost any receiver nowadays has it. Uses matrixed surround in order to encode four channels of sound: left/right front channels, a center channel, and one surround channel. It is quite a common occurrence to see two speakers used for the one surround channel however, as well as a subwoofer to supplement the speakers.
Dolby Surround
Another surround format that came out before Dolby ProLogic. It consists of only three channels: left/right front channels, and one surround channel. 2 - Another surround format that came out before Dolby Prologic. It consists of only three channels: left/right front channels, and one surround channel.
Front Projector
One type of viewing device. This is a separate unit that projects the image onto a screen allowing screen sizes of over 300".
Gain
A measurement made to determined the screen reflectance. The higher the number, the greater light is transmitted to the audience.
HDTV (High Definition Television)
New viewing standard with an aspect ratio of 16:9/1.78:1. It is slated to have over 1000 lines of resolution, as well as to have Dolby Digital be the official sound format. There is an analog system in Japan , and a digital system proposed by the Grand Alliance for the US . This system is supposed to co-exist with the current standard and eventually replace NTSC around the year 2006.
LCD Projector ( Liquid Crystal Display)
Transmits light through a tiny LCD screen and then projects it for a larger image. One major benefit is that convergence and adjustments are not required to perfect the picture. One drawback is that this technology results in pixellisation.
Light-Valve Projector
One type of front projector. It combines the technologies of LCD projectors and CRT projectors. They offer exceptional detail and brightness. Line Doubler/Tripler/Quadrupler Doubles, triples or quadruples the number of lines that make up a picture, therefore increasing detail, and ridding the picture of scan lines. Usually used with front projectors.
NTSC
The standard by which TV is broadcast in the US . It has a theoretical maximum resolution of 525 lines. Also has an aspect ratio of 4:3 or 1.33:1.
PAL
The standard by which TV is broadcast in Europe . It has a theoretical maximum resolution of 625 lines. Also has an aspect ratio of 4:3/1.33:1, and in some places 16:9/1.78:1.
Rear Projector
A type of viewing device: A translucent pane of glass or acrylic with a customized coating and structure to optimally refract video and computer imagery projected onto the side farthest from the audience.
Resolution
A term associated with the number of lines that make up the vertical portion of the picture. The higher the number, the more detailed the picture.
Screen
What the picture is projected onto. The screen is more important when it comes to front projectors, when the screen must be bought separately.
Viewing Angle
The angle at which a person is able to stand in regard to an image and still be able to see the entire image without distortion.
Widescreen
Term used to describe a picture in which the aspect ratio is wider than the NTSC standard of 4:3/1.33:1. Almost all movies made nowadays are shot in some widescreen format. To solve the problem of different aspect ratios, several different techniques can be used. Among them are anamorphic squeezing, letterboxing, and Pan and Scanning.
