Below is a list of some common terms used in the presentation industry. Scroll through the entire list or click on a letter
below to search for a specific term.
Active Matrix LCD
A type of liquid crystal display (LCD) technology where each pixel is
actively controlled by a diode or a transistor, allowing greater color
and contrast quality than passive matrix LCD. The advantage is that each
pixel can be independently controlled.
Active Matrix TFT
A common type od LCD used in laptops, cameras, and
LCD projection panels that were produced in the late 1980s to early 1990s.
A typical active matrix TFT display is a single panel of LCD glass that
controls all three primary colors. TFT displays are noted for their quick
response time and their ability to display full motion video and animations
without image ghosting.
Ambient Light
Any light in the viewing room created by a source other
than the projector or screen.
Anamorphic Lens
An anamorphic lens is a lens that has different optical
magnification along mutually perpendicular radii. This provides the ability
to project a source image of one aspect ratio, such as 4:3, into a different
aspect ratio, such as 16:9, by using different magnifications for the
horizontal and vertical dimensions of the projected image.
ANSI Lumens
A measurement of the overall projector brightness,
representing the average of 9 points on the projected screen image on
a scale devised by the American National Standards Institute (ANSI). Depending
on the lamp, optics, and projector design, ANSI lumens range from 200
to 10,000 per projector.
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 x 4/3 = 12). A
resolution of 640x480 is a 4:3 format
(480 x 4/3 = 640). SXGA is a 5:4 aspect ratio (1280x1024), HDTV is 16:9
aspect ratio, and 35mm slides have a 3:2 aspect ratio.
Auto Balance
A system for detecting errors in color balance in black
and white areas of the picture and automatically adjusting the white and
black levels of both the red and blue signals as needed for correction.
Back Room Projector
A projector with a "long-throw" lens designed
to be used from the far back of the room, often in a projection booth,
balcony, or back of an auditorium. Many typical projectors have third
party lenses available for long-throw applications.
Backlit
Refers to a remote control, projection control panel,
or other object illuminated from behind. This is an asset when using the
projector in a darkened or semi-darkened room. Many projectors have backlit
remote controls, while the number of projectors with backlit control panels
is much smaller. As projectors have gotten brighter, room lights tend
to stay on, making the need for backlit controls less important.
Brightness
The attribute of visual perception in accordance with
which an area appears to emit more or less light. (Luminance is the recommended
name for the photo-electric quantity which has also been called brightness.)
Brightness is measured in lumens on a projector.
Bulb
A light source commonly mistaken for the light source
within a projector. Bulbs power incandescent room lighting. Lamps power
projectors.
Coated Optics
A variety of materials are put on to high quality lenses
for several reasons. One of the key reasons is to minimize the amount
of light reflected back to the lamp, and the amount of ambient light that
mingles with the focused light leaving the lens. Generally, good coatings
can add 15% or more to the brightness of a lens. Other coatings are used
for filtering colors.
Color Dynamics
"The whitest whites, reddest reds, etc."
High color dynamics are a result of dynamic range/contrast ratios. When
a unit is described as having excellent color dynamics, the practical
description might be "rich colors, excellent definition, and high
contrast."
Color Temperature
A method of measuring the "whiteness" of
a light source. Metal halide lamps have very high color temperatures compared
to halogen or incandescent lights.
Compatibility
Relates to the video and computer signal formats the
projector is capable of displaying.
Component Video
Component Video is a method of delivering quality vide
(RGB) in a format that contains all the components of the original image.
These components are referred to as luma and chroma and are defines as
Y'Pb'Pr' for analog component and Y'Cb'Cr' for digital component.
Composite Video Signal
The combined picture signal, including vertical and
horizontal blanking and synchronizing signals.
Compressed Resolution
Most projectors automatically accept images that are
of greater resolution than the native (true) resolution of the projector.
The resulting image is scaled to fit the native resolution of the projector
using a variety of scaling algorithms. Not all projectors use the same
compression algorithms; therefore, the quality of compression can vary.
The nature of compression in a digital device means that some image content
is lost.
Compressed SVGA
Unlike CRT monitors, LCD and DLP projectors only have
one "true" resolution. Most projectors on the market are VGA
(640x480) resolution. To project an 800x600 image to a VGA projector,
the original 800x600 signal must be compressed down to VGA. This is done
by interpolating the data and trying to best display all the information
with only two-thirds of the pixels (307,000 vs 480,000). the resulting
image gives you SVGA page size, but some sacrifice of image quality.
Compressed SXGA
Found on XGA projectors, compressed SXGA handling allows
these projectors to handle up to 1280x1024 SXGA resolution.
Compressed XGA
Found on SVGA projectors, compressed XGA handling allows
these projectors to handle 1024x768 XGA resolution.
Compression Mode
A method of displaying images in a reduced size format.
A compressed image usually has part of the image information discarded.
The result is a projected image that has light and dark lines and text
characters with thick and thin line widths.
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.
Convergence
The alignment of the red, green, and blue video image
signals on a projected display system.
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 foot high,
12 foot wide screen has a diagonal of 15 feet (traditional 4:3 ratio).
Even if the screen is 12x12 ft., the diagonal is still 15 feet because
that would be the diagonal of the usable area.
Display Size
The diagonal length of the LCD plate. Typical sizes
are 8.4" to 12.1".
DLP
Acronym for Digital Light Processing, a data projection
technology developed by Texas Instruments using a microprocessor to display
bright, colorful images in fully lit rooms. Used primarily in portable
and ultra-portable projectors, the DLP chip is the size of a postage stamp
and contains millions of microscopic mirrors - one for each pixel - that
flip on an axis, reflecting light through a color wheel to create an image.
DVI
Acronym for Digital Visual Interface. DVI is a standard
that defines the digital interface between digital devices, such as projectors
and personal computers. For devices that support DVI, a digital to digital
connection can be made that eliminates the conversion to analog and thereby
delivers an unblemished image.
F-number
Refers to the amount of brightness that a lens allows
through the screen. Ideally, the f-number should not deviate much from
different zoom angles.
Field
One half of a video frame consisting of either all
of the even-numbered scan lines or all of the odd-numbered scan lines
in a frame.
Focal Length
The distance from the surface of a lens to its focal
point. A smaller focal length indicates a wider-angle lens.
Focus
A point at which rays of light converge. It is adjusted
to clarify a blurry image.
Front Room Projection or Position
Front projection is when a projection unit sits in
front of the screen.
Genlock
Synchronizing signals between two video sources, which
is necessary when overlaying computer graphics on an image from a 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.
Halogen Lamps
Used in most low and medium priced projectors, these
lamps last about 40 hours, with consistent output throughout the lamp
life. Although halogens look very white compared to a normal incandescent
lamp, they are not a s white as metal halide units. Cost of operation
is generally under $0.50 per hour. Most projectors using halogen lamps
carry a spare lamp inside.
HDTV
AKA High Definition Television. High definition, wide-screen
television broadcasting with digital audio.
High Gain Screen
A screen that uses one or 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.
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.
Image Size
The size of a projected image, usually measured diagonally.
Infra-Red (IR) Remote
The traditional remote control, it transmits infra-red,
like a television remote control. Typical range is limited to 30 or 35
feet. Infra-red requires line of sight or a bounce off a hard surface.
The presenter must pay attention to where the remote is pointed. Some
projectors have an IR sensor in both the front and rear of the projector,
which can be useful. When working at or near the maximum distance, pointing
directly at the receiver is necessary.
Interlaced Video
Video systems in which each frame of video consists
of two video fields. The odd-numbered lines are contained in the first
field and the even-numbered lines are contained in the second field. When
the image is delivered to a video device, such as a television, the odd
and even fields are delivered at 50 or 60 fields per second so you see
an integrated image.
Interlacing
Technique used to reduce flicker caused when the first
created video field fades while the next is being written.
Invert Image
Many projectors that are ceiling-mounted are mounted
upside down. Invert image corrects the image digitally so your projected
image does not appear upside down. Projectors typically are ceiling-mounted
upside down because most have built-in keystone correction to compensate
for the distortion created by "pointing up" from the table to
the screen. Usual positioning has the projector nearly even with the bottom
of the screen in a table top position, or, when ceiling-mounted, even
with the top of the screen.
Keystone/Keystoning
Keystoning is the distortion that occurs when the projector
is not perpendicular to the screen. Instead of a rectangular image, the
incorrect image is typically shown to be wider across the top and shorter
across the bottom, resembling the keystone of an arch.
Keystone Correction
Keystone correction makes the projected image rectangular.
This can be accomplished by positioning the projector to be perpendicular
to the screen. Since this is not always possible, most projectors are
equipped with keystone correction that allows the image to be keystone
corrected by adjusting optics, making mechanical adjustments, or applying
digital correction to the image. Keystone correction can be one or two
dimensional and manual or automatic depending on the projector and the
manufacturer.
Lamp
The bright source of a projector partially responsible
for the sharpness and clarity of an image.
Lamp Life
Lamps used in projectors tend not to burn out suddenly,
but to dim gradually. Lamp life refers to how long the lamp can be on
until it starts to become too dim for adequate use. The life expectancy
of the lamp in the projector varies from 40-70 hours on the low end (mainly
halogen lamps) to as many as 4,000 hrs. Fortunately, most projectors today
have lamps that will last at least 1,000 hours. That may be adequate to
meet your needs, but keep in mind that most lamp replacements cost anywhere
from $200 to $500. Two of the most common lamp types are metal halide
and UHP lamps. Both types project very white light and typically last
750 to 2000 hours. In contrast, halogen lamps have shorter lives and tend
to project a more yellow image. Xenon lamps are often used in high-end
projectors.
LCD
Acronym for Liquid Crystal Display. Liquid crystals
exist in an intermediate state between liquid and solid, and realign under
electrical stimulation. This technology comes in many forms, sizes and
resolutions. Its primary purpose is to present a digital image for viewing.
Exceptionally slim and lightweight, LCDs are commonly used in many notebook
computer displays, TV displays, and inside projectors to project high-resolution
digital images.
Lens Shift
The lens shift feature of a projector allows the optical
lens to be physically shifted up and down (Vertical) or left and right
(Horizontal). Most lens shift mechanisms are motorized with vertical lens
shift being the most popular. Projectors that have lens shift allow users
to optically correct for keystone distorted images. The lens shift feature
is also used to help geometrically align images when stacking projectors.
Lenticular
A screen surface with 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 in a projection booth in the back of a
theater, or from the back of a large classroom. Long throw lenses enable
a projector to decrease its image size over the standard lens at the same
throw distance. With a long throw distance the user is able to project
a smaller image so it will fit on the screen. A typical long throw lens
might have to be used 50 to 100 feet back to project a 10 foot diagonal
image.
Lumen
A unit of measurement of the amount of visible light
energy coming from a light source and perceived by the eye. One lumen
is the light of one candle power on each square foot of a sphere at a
radius of one foot from the light source.
Lux
A standard for measuring light. Numbers provided by
manufacturers often do not provide the necessary additional information
needed to compare one projector to another.
Maximum Distance
Sometimes, though rarely, this refers to the distance
from the screen that a projector can focus the image. Most of the time,
it is the manufacturer's opinion of how far from a screen the projector
can be to cast a useable (bright enough) image in a fully darkened room.
Generally, this is very subjective. One projector might quote a distance
that allows it to produce a 25 foot diagonal image, while another, brighter
projector might quote a distance equal to only a 20 foot diagonal image.
Maximum Image Size
The largest image a projector can throw in a darkened
room. This is usually limited by the focal range of the projector's optics.
Menu Driven
This refers to the type of controls on a projector.
A typical menu driven system will first offer a menu of major categories,
such as Computer, Video, Audio, Display, Options, etc. After selecting
a choice from the main menu, another menu appears with more specific options
related to your original menu choice. Many projectors which are menu driven
also offer the most widely used functions in a non-menu fashion as well.
For example, there might be separate buttons on the remote for volume,
brightness, contrast, etc.
Metal Halide Lamp
This is the type of lamp used in most high-end, portable
projectors. They typically have a half-life of 1000-2000 hours. This means
that they slowly lose intensity (brightness) as they are used, and that
at the "half-life" point, they are half as bright as when new.
Metal Halide lamps output a very "hot" temperature light, similar
to mercury vapor lamps used in street lights. Metal Halide whites are
super white (with a hint of blue) and make the white light of a Halogen
lamp appear very yellowish by comparison.
Mid Room Projector
Designed to sit in a position that is not too close
or too far from the screen. For a 10 foot screen, typical placement is
12.5 to 25 feet away. Most mid-room projectors have zoom lenses.
Minimum Distance
The closest position that a projector can focus an
image onto a screen.
Multimedia Presentations
The integration of text, art, graphics, photography,
animation, audio, and video into presentations.
Multiplexing
The condensing of many signals into a few signals or
a single signal that still represents all of the original signals. 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.
Native Resolution
The computer resolution that optimizes the projector
resolution. When buying a projector, you should always match the resolution
of your notebook to the native resolution of your projector.
Network
Connecting two or more computers and/or networkable
devices for data sharing or remote control of devices.
Non-Interlaced
Each line is scanned during each total vertical (full)
screen refresh.
NTSC
Acronym for National Television Systems Committee,
the standard for the United States, administered by the Federal Communications
Committee (FCC). NTSC is 525 lines of resolution transferred at a rate
of 30 frames per second.
PAL
Known as Phase Alternate Line, PAL is the standard
color system for video and broadcasting used throughout Western Europe
(except France). The phase of the color carrier alternates from line to
line. PAL is 625 lines of resolution transferred at 25 frames per second.
Passive Matrix
The use of simple driver electronics in an LCD projector
panel where the pixels are turned on and off using a row-and-column format.
the amount of control on each pixel is limited, which results in lower
contrast ratios and a slower response time than active-matrix LCD projection
panels.
Poly-Si (silicon) LCD
A popular LCD technology for top of the line LCD projectors.
Monochrome Poly-Si LCDs are typically placed in each of the three color
light paths inside a projector, one each of Red, Green, and Blue. This
results in increased color saturation, with contrast ratios above 200:1.
Poly-Si technology is also a bit faster than the Active Matrix TFT for
smooth video and multimedia.
Pixel
Short for picture element. The smallest graphic unit
that can be displayed on the screen, usually a single-colored dot. A color
pixel is a combination of red, green and blue subpixels. Total pixels
are usually expressed in horizontal x vertical dimensions (e.g. 640 x
480).
Power Down
A modern term for turning something off.
Power Zoom
A zoom lens with the zoom in and out function controlled
by a motor, usually adjusted from the control panel or a remote control.
Progressive Scan
A type of display in which all the horizontal lines
of an image are displayed at one time in a single frame. Progressive scan
is unlike an interlaced scan in which a frame consists of two separate
fields with the first field of odd horizontal lines and the second field
of even horizontal lines. Progressive scan is used by projectors, computer
monitors, some TVs and HDTV systems, and some digital camcorders.
Projection Axis
Direction of the "imaginary" line that extends
from the center of the projection lens through the center of the screen.
Projector
A projector is a device that integrates a light source,
optics system, electronics, and display(s) for the purpose of projecting
an image from a computer or video device onto a wall or screen for large
image viewing. There are hundreds of products available in the market
and they are differentiated by their resolution, performance and features.
These devices attach to a computer or video device the same as you would
connect a monitor.
QXGA
QXGA is used to define a specific display resolution.
Resolution is defined by the number of individual dots that a display
uses to create an image. These dots are called pixels. A QXGA display
has 2048 horizontal pixels and 1536 vertical pixels giving a total display
resolution of 3,145,728 individual pixels that are used to compose the
image delivered by a projector. A QXGA display has four times the resolution
of an XGA display.
Real Time
The transfer of data that returns results so quickly
that the process appears to be instantaneous.
Rear Screen Projection
Projecting an image through a translucent screen material
for viewing from the opposite side. With rear projection, the projector
is placed behind the screen, invisible to the audience. It projects onto
the screen and the audience sees the image on the other side. Since the
image is projected through the screen, the image must be reversed. Good
rear projection screens actually produce brighter images than some standard
screens. Ideally a projector with a short throw lens is used to avoid
wasting space behind the screen. The projector can be placed even with
the middle of the screen, without blocking anyone's view, so keystoning
is not a problem.
Refresh Rate
The number of times the screen image is "painted"
or refreshed per second, expressed in Hz.
Remote
A small handheld device separate from the projector,
which contains projector controls, such as volume, brightness, etc. The
remote control allows the presenter freedom of movement.
Resolution
The number of screen pixels that can be displayed by
a projector. Most units have a standard of 640x480 pixels or 800x600 pixels
(VGA and SVGA, respectively). More pixels per unit of area produce a higher
resolution, giving more detail in the display of an image. Some higher
resolutions include, XGA (1024x768 pixels) and SXGA (1280x1024 pixels).
Response Time
The time it takes for a pixel to turn on and off. Typically
measured in milliseconds, an active matrix LCD projection panel's response
time is fast enough to display full-motion video and rapid mouse cursor
movement.
Reverse Image
Reverse image is a feature found on most projectors
that flips 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. The basic signal components of the
color video signal.
RS-232C
A cable that connects a computer and its peripherals.
Scaler
A scaler, also know as a video line doubler or scan doubler, increases
the number of lines of vertical resolution from 525 to 1,050 lines. Though
it starts with a fixed, 525-line signal, the device uses a mathematical
algorithm to create 525 more lines in between the lines coming from the
signal. The result is a much sharper image. Nearly all LCD projectors
today include some type of video scaler, since they must scale the 525-line
image to the native resolution of the projector.
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. This format offers a higher quality than composite video, but
a lower quality than component video.
SECAM
Sequential Couleur Avec Memorie. The color television
standard developed in France. SECAM is mostly used in France and Eastern
European countries. 625 lines/50Hz.
Serial Port
A data I/O port on the computer enabling other devices
or computers to link with the computer. Also referred to as RS-232C or
COM port.
Short Throw Lens
A lens designed to project the largest possible image
from a short distance. Most front room projectors use short throw lenses.
They are often required for rear projection, where the depth behind the
screen is limited. A typical short throw lens might produce a diagonal
image size of 10 feet from a distance of 7 to 10 feet. A short throw lens
enables the projector to increase its image size over the standard lens
at the same throw distance. The user can create larger images at closer
distances.
SVGA
Acronym for Super Video Graphics Display. SVGA is used
to define a specific display resolution equating to 800x600 pixels.
SXGA
Acronym for Super Extended Graphics Adapter. SXGA is
used to define a specific display resolution equating to 1280x1024 pixels.
UHP
Acronym for Ultra High Performance and/or Ultra High
Efficiency, a term typically used with metal halide lamps that power ultra-bright
projectors.
Uniform Brightness
The lack of brighter or dimmer areas of a projected
image across a lighted surface.
USB
Acronym for Universal Serial Bus, a peripheral connection
interface for low-speed devices. Notable for its easy swapability.
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 mode, typically
the projector will resize the image to 1600x1200.
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.
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.
Video Standards
The type of video inputs an LCD projector can accept.
Leading standards include NTSC, SECAM, and PAL.
VGA
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). 720x400 resolution in text mode, 640x480
resolution in graphics mode.
WSXGA
WSXGA defines a class of SXGA displays with a width
resolution sufficient to create an aspect ratio of 16:9. Resolution is
defines by the number of individual dots (pixels) that a display uses
to create an image. A WSXGA display has 1920 to 1600 horizontal pixels
and 1080 to 900 vertical pixels respectively that are used to compose
the image delivered by the projector.
WXGA
WXGA defines a class of XGA displays with a width resolution
sufficient to create an aspect ratio of 16:9. Resolution is defines by
the number of individual dots (pixels) that a display uses to create an
image. A WXGA display has 1366 to 1280 horizontal pixels and 768 to 720
vertical pixels respectively that are used to compose the image delivered
by the projector.
Xenon Arc Lamp
The same light source used in motion picture projectors,
produces pure, white illumination to ensure color accuracy and saturation.
Lamps have a stable color over their 1000 hour life.
XGA
Acronym for Extended Graphics Adapter. A graphics standard
introduced by IBM that includes VGA and extended resolution up to 1024x768
pixels.
Zoom Lens
A lens with a variable focal length providing the ability
to adjust the size of the image on a screen by adjusting the zoom lens,
instead of having to move the projector closer or further away from the
screen.
Zoom Lens Ratio
This 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. Conversely, a 10 foot diagonal image at 15 feet
with no zoom would still be 10 foot image at 21 feet at maximum zoom (15
x 1.4 = 21 feet).
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