Ambient Light
All light in a viewing room produced by sources other than the screen.

Aspect Ratio
The numeric relationship between a screen's height and width. This ratio is often defined by the selected projection medium. Hence, NTSC Video (U.S. television) has an aspect ratio of 3:4.

Bend Angle
The angle through which a projected light ray must be diverted from its original path to reach a viewer's eyes.

Borders
The black portion surrounding the viewing area of a screen.

Brightness
A viewer's subjective response to luminance.

Contrast Ratio
The numeric relationship between the brightest and the darkest portions of a display expressed in foot-lamberts as a ratio of Max:Min.

CRT
Cathode Ray Tube. Same technology used in TV and computer monitors.

DLP
This technology is based on the Digital Micromirror Device™ (DMD™) which uses over 500,000 microscopic mirrors on the SVGA chip to reflect images on screen.

Drop
The area between the top of the viewing area and the bottom of the screen housing.

Foot-Candle
The fundamental unit of illumination representing the light intensity over a 1 square foot surface which is 1 foot away from a standard candle.

Foot-Lambert
A unit of luminance equivalent to 1 lumen per square foot.

Gain
A measurement usually made perpendicular to screen center of the luminance transmitted by the screen, divided by the luminance radiating from the projector.

HDTV
Acronym for High Definition Television

Keystone
The distortion of the projected image when the screen is not perpendicular with the center line of the projected image.

LCD
Liquid Crystal Display. Commonly used in digitized projection.

Lenticular
Screen surface comprised of a geometric embossing pattern. The shape of the pattern affects view\angle performance and reflection of ambient light.

Luminance
The measured brightness of a screen, expressed in foot-lamberts.

Projection Axis
The direction of an imaginary line extending from the center of the projection lens through the screen's center.

SVGA
Super Video Graphic Array. Common computer screen resolution. (800 x 600)

Throw Distance
The length of the projection beam necessary for a particular projector to produce an image of a specified size.

VGA
Video Graphic Array. Common computer screen resolution. (640 x 480)

Viewing Angle
The angle from a specified viewing position to the center of the screen. It is usually measured on the horizontal or on the vertical axis. Specified in this guide as optimum screen brightness from screen center to either side.