ANSI Lumens - A standard for measuring the brightness. It is calculated by dividing a square meter image into nine equal rectangles, measuring the lux (or brightness) reading at the center of each rectangle, and averaging these nine points.
Aspect Ratio - The most popular aspect ratio is 4:3 (4 by 3). Early television and computer video formats are in a 4:3 aspect ratio, which means that the width of the image is 4/3 times the height.
Brightness - The amount of light emitted from a display or projection display or projection device. The brightness of projector is measured by ANSI lumens.
Color Temperature - The color appearance of white light. Low color temperature implies warmer (more yellow/red) light while high color temperature implies a colder (more blue) light. The standard unit for color temperature is Kelvin (K).
Component Video - A method of delivering quality video in a format that consists of the luminance signal and two separate chrominance signals and are defined as Y'Pb'Pr' for analog component and Y'Cb'Cr' for digital component. Component video is available on DVD players.
Composite Video - A video signal that combines the luma (brightness), chroma (color), burst (color reference), and sync (horizontal and vertical synchronizing signals) into a signal waveform carried on a single wire pair. There are three kinds of formats, namely, NTSC, PAL, and SECAM.
Compressed Resolution - If the input images are of higher resolution than the native resolution of the projector, the resulting image will be scaled to fit the native resolution of the projector. The nature of compression in a digital device means that some image content is lost.
Contrast Ratio - Range of light and dark values in a picture, or the ratio between their maximum and minimum values. There are two methods used by the projection industry to measure the ratio:
1 Full On/Off - 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 - measures 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.
Full On/Off - contrast is always a larger number thanANSIcontrast for the same projector.
dB - decibel - A unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels.
Diagonal Screen - A method of measuring the size of a screen or a projected image. It measures from one corner to the opposite corner. A 9 FT high, 12 FT wide, screen has a diagonal of 15 FT. This document assumes that the diagonal dimensions are for the traditional 4:3 ratio of a computer image as per the example above.
Digital – relating to an audio recording method in which sound waves are represented digitally (as on magnetic tape) so that in the recording wow and flutter are eliminated and background noise is reduced.
DHCP - Dynamic Host Configuration Protocol - A network protocol that enables a server to automatically assign a TCP/IP address to a device.
DLP®—Digital Light Processing™—Reflective display technology developed by Texas Instruments, using small manipulated mirrors. Light passing through a color filter is sent to the DLP mirrors which arrange the RGB colors into a picture projected onto screen, also known as DMD.
DMD - Digital Micro-Mirror Device - Each DMD consists of thousands of tilting, microscopic aluminum alloy mirrors mounted on a hidden yoke.
DNS - Domain Name System - An Internet service that translates domain names into IP addresses.
Document Camera - Document cameras, also less commonly referred to as visual presenters digital visualizers, docucams and digital overheads, are real-time image capture devices for displaying an object to a large audience. They are intended to replace overhead projectors in presentation scenarios such as classrooms, courtrooms, labs, and boardrooms. In addition to displaying information from traditional mediums such as foils, transparencies or slides, a document camera’s higher resolution allows the user to project text, photos or three dimensional objects in great detail.
A document camera when connected to a projector allows objects and printed material to be electronically presented to a large audience. It is ideal for presenting material that is not readily available in electronic form.
Focal Length - The distance from the surface of a lens to its focal point.
Frequency - It is the rate of repetition in cycles per seconds of electrical signals. Measured in Hz (Hertz).
HDCP - High-Bandwidth Digital - Content Protection - A specification developed by Intel™ Corporation to protect digital entertainment across digital interface, such as DVI, HDMI.
HDMI - High-Definition Multimedia Interface - HDMI carries both uncompressed high definition video along with digital audio and device control data in a single connector.
Hz - Hertz - Unit of frequency.
Interactive - Projector/Whiteboard - This technology encompasses any solution that enables active participation by the user with the projected content, rather than just the passive viewing of content.
IEEE802.11 - A set of standards for wireless local area network (WLAN) communication. 802.11b/g uses the 2.4 GHz band.
Keystone Correction - Device that will correct an image of the distortion (usually a wide-top narrow-bottom effect) of a projected image caused by improper projector to screen angle.
Maximum Distance -The distance from a screen the projector can be to cast an image that is usable (bright enough) in a fully darkened room.
Maximum Image Size - The largest image a projector can throw in a darkened room. This is usually limited by focal range of the optics.
Minimum Distance - The closest position that a projector can focus an image onto a screen.
NTSC - National Television Standards Committee - North American standard for video and broadcasting, with a video format of 525 lines at 30 frames per second.
PAL - Phase Alternating Line - A European broadcast standard for video and broadcasting, with a video format of 625 lines at 25 frames per second.
Reverse Image - Feature that allows you to flip the image horizontally. When used in a normal forward projection environment text, graphics, etc. are backwards. Reverse image is used for rear projection.
RGB - Red, Green, Blue - typically used to describe a monitor that requires separate signals for each of the three colors.
S-Video - A video transmission standard that uses a 4-pin mini-DIN connector to send video information on two signal wires called luminance (brightness, Y) and chrominance (color, C). S-Video is also referred to as Y/C.
SECAM - A French and international broadcast standard for video and broadcasting, closely related to PAL but with a different method of sending color information.
SSID - Service Set Identifiers - A name used to identify the particular wireless LAN to which a user wants to connect.
Short Throw Projector - Short throw projectors are used in applications where the distance to the projection screen must be minimized. Models are able to project onto a screen from as little as 1.5 feet away. These projectors come in both 4:3 and 16:9 aspect ratios and may include support for networking.
SVGA - Super Video Graphics Array - 800 x 600 pixels count.
SXGA - Super Extended Graphics Array - 1280 x 1024 pixels count.
UXGA - Ultra Extended Graphics Array - 1600 x 1200 pixels count.
VGA - Video Graphics Array - 640 x 480 pixels count.
WEP - Wired Equivalent Privacy -This is a method for encrypting communication data. The encryption key is created and notified only to the communicating user, so the communication data cannot be decrypted by a third party.
XGA - Extended Video Graphics Array - 1024 x 768 pixels count.
WXGA - Wide Extended Graphics Array - 1280 x 800 pixels count.
Zoom Lens - Lens with a variable focal length that allows the operator to move the view in or out making the image smaller or larger.
Zoom Lens Ratio -Is the ratio between the smallest and largest image a lens can project from a fixed distance. For example, a 1.4:1 zoom lens ratio means that a 10 foot image without zoom would be a 14 foot image with full zoom.