Aspect Ratio
refers to the difference between the width and height of the screen, expressed as a ratio.  See Aspect Ratios.

AV Format (Audio Video Format)
is an aspect ratio 1:1, where the width is the same as the height.  See Aspect Ratios.

Colour Shift
occurs if the screen is not reflecting true colours.  All colours may appear slightly more red or blue, depending on the problem.

DLP Projectors
Digital Light Processing projectors are a new technology developed by Texas Industries.  In terms of optical characteristics, they are similar to LCD projectors, and their performance is optimised by the use of matte white projection material in a dark room, or a black screen in a light room.

DVD (Digital Video Disc)
A method of storing digital data, used for high quality images.  This usually requires a 16:9 aspect ratio (HDTV format).

Fixed Screen
See Frame Screen.

Frame Screen
A screen where the material is stretched under tension in a frame. See, for example,
LP Morgan Galleria

Front Projection
Where the screen is projected onto from the front (i.e.. the same side as the viewer).

Gain
A measurement of the reflectivity of the screen.  High gain screens were necessary for old projectors with low light output.  However, teaming a high gain fabric with a contemporary projector will result in two compromises - a narrow viewing angle and possible colour shift.
Matte white (gain = 1.1) is best for modern projectors in dark rooms.
Black screens (gain = 2) is best for modern projectors in light rooms.
See Screen Materials.

Galleria
A Frame Screen made in Australia by LP Morgan.

Glass-beaded
A type of screen material which uses small glass beads to increase screen gain, however there is a loss of resolution and viewing angle.  See Screen Materials.

HDTV (High Definition Television)
A modern system of television which will eventually replace current TV technology.  This system uses a different format, 16:9 instead of 4:3.  It is sometimes referred to as widescreen.

HDTV Format
The aspect ratio used for HDTV and DVD.  The ratio of width to height is 16:9 which is why it is referred to as widescreen.  See Aspect Ratios.

Hot Spot
A very strong differentiation of centre to edge brightness of a projected image.  Usually the centre is significantly brighter than the edges causing a "hot spot".  This is generally caused by poorly formulated screen materials and can be demonstrated in the most extreme example by projecting onto commercial whiteboards.  However, it should be stated that all projectors show some variation between the centre to edge brightness which is technically a hotspot, but usually it is of a degree which the human eye is unable to observe.

LCD Projectors
Liquid Crystal Display projectors are currently very popular video/data projectors.  Best results are achieved with matte white projection material in a dark room, or a black screen used in a light room.

Lenticular
An optical structure of vertically running ridge and groves.  Designed to enhance gain and horizontal viewing angle but may result in diminished resolution.

LP Morgan
An Australian manufacturer of high quality projection screens.  See LP Morgan.

Matte White
The best type of screen surface for modern projectors when used in a darkened room.  Provides best all round performance in terms of true colour reproduction, best possible resolution, widest possible viewing angle, no glare, zero hot spotting and can be washed if necessary.  See screen materials.

Maximum Viewing Distance
The distance from the screen to the furthest point from which a person will view the image comfortably. See Screen Sizes.

Minimum Viewing Distance
The distance from the screen to the closest point from which a person will view the image comfortably. See Screen Sizes.

Pearlescent
A synthetic mother of pearl spray on screen surface designed to increase screen gain to about 2.0 to 2.5.  Image quality may be compromised by a slight colour shift towards the red spectrum.  Additionally, the slightly shiny finish may promote hot spotting.

Plana U
A fabric used for LP Morgan Rondo screens and LP Morgan Galleria screens.

Rear Projection
A projection system were the projector is situated behind a translucent screen.  Used for situations with a lot of ambient light, but this technology has now mostly been replaced by front projection with black screens. See for example, Galleria Noir.

Resolution
The "sharpness" of an image.  The higher the resolution, the higher the sharpness quality.

Roller Screen
A screen which rolls down for use and rolls up out of the way when not in use.  See, for example, LP Morgan Rondo.

Rondo
A high quality, Australian made roller screen by LP Morgan.

Universal Mounting System (UMS)
A unique feature to LP Morgan screens which enables extremely easy installation as the wall or ceiling brackets may be mounted anywhere along the length of the case.

Video Format
A 3:4 ratio for viewing images from television, laser disc, video or a data source such as power point presentations.

Viewing Angle
The angle from which a person will be able to view the screen where the brightness is at least half as strong as when viewed directly from the front.

Viewing Distance
The distance from the screen to the point at which a person views the screen.  See Selecting the Correct Screen Size.