Ambient Light:

Any light in the viewing room created by a source other than the projector or screen.

Aspect Ratio:

The ratio of height to width of a frame or screen. In a 4:3 aspect ratio, the width of the image is 4/3 times the height. Most current TV and computer video formats are in a 4:3 aspect ratio. A 15 inch monitor is 12 inches wide by 9 inches high (9*4/3 = 12). A resolution of 640x480 is a 4:3 format (480*4/3 = 640). SXGA is a 5:4 aspect ratio is (1280x1024), HDTV is 16:9 for that movie theater feel, and 35mm slides are 3:2.

ANSI Lumens:

ANSI stands for American National Standards Institute. It is a standard for measuring light output. Different lamps play a role on light output. Halogen lamps appear dimmer than another metal-halide, even if the two units have the same ANSI lumen rating. Type of LCD technology (active matrix TFT, Poly-Si, passive), type of overall technology (LCD vs. DLP vs. CRT), contrast ratios, among other factors can also affect the end result.

Aliasing:

Jagged edges along the outer edge of objects or text. Anti-aliasing refers to software adjustments that correct this effect. This effect is created by inadequate sampling techniques in computer-produced images.

Bandwidth:

The frequency range of a particular transmission method. In video systems, this value is expressed in MHz, and the better the signal, the greater the bandwidth required.

Color Temperature:

A method of measuring the "whiteness" of a light source. Metal halide lamps produce higher temperatures than halogen or incandescent lights.

Color Resolution:

The total number of colors available, expressed in bits per pixel.

Compatible:

When different hardware or software can be used together without a major over-haul.

Contrast Ratio:

The ratio between white and black. The larger the contrast ratio the greater the ability of a projector to show subtle color details and tolerate extraneous room light. There are two methods used by the projection industry: 1) Full On/Off contrast measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. 2) ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio. When comparing the contrast ratio of projectors make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same projector.

Diagonal Screen:

One corner of a screen to the opposite corner. A 9FT high, 12FT wide, screen has a diagonal of 15FT. If the screen is 12x12, it would still rate 15FT diagonal since that would be the diagonal usable.

Digital Light Processing (DLP):

Developed by Texas Instruments, DLP is a light processing system that utilized hundreds of thousands of tiny spinning mirrors to reflect images. Many feel it is the most accurate reproduction of color and images available today.

Dot Pitch:

The distance between the dots on a CRT display. The closer together the dots are create a higher resolution of a displayed image.

Dithering:

Making digital images appear smoother by adding color or random noise during the digitization process.

EGA:

AKA Enhanced Graphics Array, EGA is an image which displays 640 pixels by 350 lines with 16 colors from a palette of 64 colors.

Front Room Projector or Position:

A unit that sits close to the screen, its short throw lens projects an image size that is about the same as the distance to the screen. 6FT diag. screen = 6FT distance. Generally the unit might be as close as 3/4 the screen size or as far as 1.2 times image size.

Front Room Projector or Position:

A projection unit that sits close to the screen, thereby requiring a shorter throw-distance.

Flat Screen:

A CRT made more flat than a standard tube by using more than one electron gun. Beneficial to people who require concise reproduction and great detail such as graphic designers.

Focal Length:

Focal length is the distance between the lens and its focal point. A smaller focal length indicates a wider-angle lens.

Genlock:

Synchronizing signals between two video sources, which is necessary when overlaying computer graphics on an image from VCR, camera, or videodisc player.

Ghosting:

A shadow or weak secondary image as seen on a monitor or display which is created by multiple path broadcast transmission errors.

High Gain Screen:

A screen that uses one of more methods to collect light and reflect it back to the viewing audience, which will increase the brightness of the image over a white-wall or semi-matte screen.

H Sync:

AKA Horizontal synchronization. A marker, which indicates to a computer or video signal that it, is the beginning of a line.

HDTV:

AKA High Definition Television. High definition, wide-screen television broadcasting with digital audio. Has a 16:9 Ratio.

Horizontal Frequency:

AKA kHz, the total number of horizontal lines scanned per second in a displayed image.

Horizontal Resolution:

The total number of vertical lines individually perceived across the horizontal rows of a monitor.

Hz:

AKA Hertz. A measure of frequency in cycles per second. Used to express the frequency of an electrical signal or event.

Invert Image:

Many projectors that are ceiling mounted are mounted upside down. Invert image corrects the image digitally so your projected image is not also upside down.

Interlacing:

Technique used to reduce flicker caused when the first created video field fades while the next is being written.

Keystone Correction:

A projectors ability to correct the effects of "pointing up" or "pointing down" at a screen enabling the projector user’s audience to view a rectangular image rather than one with a wider top or bottom.

Keystoning:

The distortion (usually a wide-top narrow-bottom effect) of a projected image caused by a projector "pointing up" or "pointing down" at its screen. Named after its similarity in shape to the keystone used in constructing an arch.

LCD:

AKA liquid crystal display. This technology comes in many forms, sizes, and resolutions. Its primary purpose is to present a digital image for viewing. They are used in many notebook computer displays and also used as technology inside a projector to project high-resolution digital images.

Laser Pointer:

A hand held device that emits a thin laser beam that focuses a bright dot (usually red) on projected images or just about anywhere. Used by presenters to direct the viewer's eye to a particular point of interest.

Lenticular:

A screen surface that has an embossed geometric shaped pattern that affects view/angle performance and reflection of ambient light.

Long Throw Lens:

A lens designed for projection from the back of a room. Long throw lenses would be used a projection booth in the back of a theater, or from the back of a large classroom. A long throw lens would have to be 50 to 100 FT back to project a 10FT diagonal image.

Metal Halide Lamp:

The type of lamp used in most high-end portable projectors. These lamps output a very "hot" temperature light, similar to lamps used in streetlights. Metal Halide whites are super white (with a hint of blue) and make Halogen lamp white very yellowish by comparison.

Multimedia Presentations:

The integration of text, art, graphics, photography, animation, audio, and video into presentations.

Multiplexing:

The condensing of many signals into a few or one signal that still represents all of them. An LCD panel performs the de-multiplex function. It takes video signals that contain whole frames of video data and displays them as individual signals on each pixel.

NTSC:

The USA’s broadcast standard for video and broadcasting. It is actually a lower resolution than systems used in most of the world. However, by the year 2002 stations will be required to broadcast higher resolution video signals. Has a 4:3 ratio. Also known as Video Format.  

Overhead Projector (OHP):

An OHP is designed to project images from transparencies onto a screen.

PAL:

AKA Phase Alternation by Line. The standard color system used throughout Western Europe, except in France.

Poly-Si (silicon) LCD:

A popular LCD technology for the top of the line LCD projectors, which results in increased color saturation, with contrast ratios above 200:1.

Power Zoom:

A zoom lens with the zoom in and out controlled by a motor, usually adjusted from the control panel or a remote control. This is as compared to Digital zoom, which does this same function Digitally.

Projection Axis:

Direction of the "imaginary" line that extends from the center of the projection lens through the center of the screen.

RGB:

Red, Green, Blue; the type of monitor generally used with computers. RGB input or output often referred to as Computer input or output.

RCA connector:

The connector used with VCRs and stereos for composite video signals and audio.

Rear Projection:

Projecting an image through a translucent screen material for viewing from the opposite side. This method of projection is also an option for home theater use in large spaces.

Resolution:

Number of pixels (or dots) per unit of area, measure in number of pixels wide by the number of pixels high that can be displayed on the screen or monitor. More pixels per unit of area produce a higher resolution.

Simulated color:

Also known as "false color," or "colorized." Projected colors that are not the same as the original image. Some products use a single, colorized LCD, often with purple for dark shades and yellow for light shades (purple background/yellow foreground). Therefore, what should appear on a screen as blue may be yellow, green may be purple.

SVGA:

AKA Super VGA. Refers to a computer signal that is higher than the standard VGA resolution of 640 pixels by 480 lines with 16 or 256 colors. SVGA graphics cards may output resolutions such as 1024 x 768, 1280 x 1024, 1600 x 1200 pixels or higher, with 16.7 million colors displayed.

Throw Distance:

Length of the projection beam required for a projector to produce and image of a desired size.

UXGA:

Resolution of a computer generated image. A UXGA projector will be able to display a 1600x1200 image from a computer running in a UXGA video mode. If the computer is not running in a UXGA video mode, typically the projector will resize the image to 1600 x 1200.

VGA Resolution:

VGA Resolution normally refers to a 640 x 480 pixel display, regardless of the number of colors available. Originally VGA was 640 x 480 16 colors.

Varifocal Lens:

A projector lens that has three focal elements contained in a single assembly.

Vertical Resolution:

The total number of horizontal lines that can be perceived in the vertical direction of the screen.

VGA:

AKA Video Graphics Array. This is the standard interface for the IBM PS/2. It is the only analog graphics card IBM has used (other cards handle digital information) 720 x 400 in the text mode, graphics mode 640 x 480 resolution.

Video Compatibility:

Ability of computers and projection units to transmit and receive data to read and/or project various video tape standards such as NTSC, PAL, SECAM and S-VHS.

XGA:

Acronym for Extended Graphics Adapter. A standard introduced by IBM that includes VGA as well as resolutions up to 1024 pixels by 768 interlaced lines.

Zoom Lens:

A lens with a variable focal length. This translates to being able to adjust the size of the image on a screen by adjusting the zoom lens, instead of hAudio Visual Innovationsng to move the projector closer or further.