Glossary
1080i: 1080i is ATSC high definition 1920 x 1080 interlaced video format where a frame of video is delivered in two fields. The first field contains the odd lines of the image, while the second field contains the even lines. Each field is updated every 1/60th of a second resulting in 30 frames of video per second.
1080p: 1080p is ATSC high definition 1920 x 1080 progressive scan video format where a complete frame of video is delivered at either 60 or 24 frames per second.
1080p: 1080p is ATSC high definition 1920 x 1080 progressive scan video format where a complete frame of video is delivered at either 60 or 24 frames per second.
16:9: Aspect ratio of an HDTV signal which is 16 units by 9 units, whatever size those units may be. In the film trade aspect ratios are described in relation to one, which means this aspect ratio is described as 16/9 or 1.78:1.
3LCD: Common 3 color system for projecting images via LCD or liquid crystal display. Uses dichroic mirrors to separate the RGB components of white light coming from a projection lamp. Each color is feed to separate LCD panels which control the about of colored light that passes through. The light from each LCD is recombined using a dichroic prism before going out the lens and on to a screen.
ANSI: American National Standards Institute. A private organization that coordinates and administers various voluntary consensus standards such as ANSI lumens. The first ANSI standard was for pipe threading in 1919 when it was called the American Engineering Standards Committee.
ANSI Contrast: Contrast is 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.
ANSI Lumens: ANSI lumens is a measurement of the overall brightness of a projector. Because the center of a projected image is brighter than the corners, ANSI lumens is the most accurate representation of the image brightness. ANSI lumens are calculated by dividing a square meter image into 9 equal rectangles, measuring the lux (or brightness) reading at the center of each rectangle, and averaging these nine points.
Aspect Ratio: The ratio of image width to image height. Standard television is 4:3 or 1.33:1. Panavision or Cinemascope is 2.35:1 with 1.85:1 being quite common as well. Widescreen displays are 1.78:1 or 16:9.times the height. For example, if you want an image 40 inches high then you need a screen that is at least 40 * 1.78 inches wide or 71 inches. Other relatively common aspect ratios are 3:2, 4:3 and 5:4.
Auto Balance: A system for detecting errors in color balance in white and black areas of the picture and automatically adjusting the white and black levels of both the red and blue signals as needed for correction.
Blooming: Video distortion where an overly bright screen object causes phosphors near it to excite therefore enlarging the object and softening its edges.
Blue Laser: Color of the laser used with Blu-ray high definition DVDs. Blue laser light has a shorter wavelength than red, which is why blue lasers can retrieve and store more data in a given physical area.
Brightness: Overall light output from an image. While a brightness control can make an image brighter, it is best used to better define the black level of the image.
Center Channel: Center designated signal of a 5.1 audio system. Typically for home theater, the corresponding speaker should be as close as possible to the video image associated with the sound.
Channel: A separate signal or signal path.
Component Video: Component Video is a method of delivering quality video (RGB) in a format that contains all the components of the original image. These components are referred to as luma and chroma and are defined as Y'Pb'Pr' for analog component and Y'Cb'Cr' for digital component. . It is comprised of luminance (Y) and two chrominance channels of blue minus luminance and red minus luminance.
Composite Video Signal: Single signal version of video where both chroma and luma are carried with chroma on a 3.58MHz sideband of the luminance signal, usually through a 75 Ohm cable. Poorest quality signal type.
Contrast: Contrast increases as the white point increases. Increasing the white point creates a greater difference between white and black.
Contrast Ratio: The ratio between white and black. The larger the contrast ratio the greater the ability of a video device to show subtle color details and tolerate ambient room light. There are two industry methods used: 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 video devices 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 video device.
CRT: Cathode Ray Tube.
D-ILA: Direct Drive Image Light Amplifier. Proprietary JVC version of LCoS light valve technology.
Diagonal: The diagonal of a screen or flat panel can be computed by using the Pythagorean theorem: squaring the width, squaring the height, adding them together and taking the square root. A 100" diagonal 16:9 screen measures 49" high by 87" wide; a 100" diagonal 4:3 screen measures 60" high by 80" wide. Use the Projection Calculator to get screen dimensions on all common aspect ratios.
DLP: DLP (Digital Light Processing) is a commercial name for a display technology from Texas Instruments (TI). The technology inside is often referred to as DMD (Digital Micro-Mirrors). It consists of an array of mirrors where each mirror represents a pixel element. For example, a high-definition DLP projector or rear projector with 1920 x 1080 pixel resolution would have over 2 million tiny mirrors. Each mirror is attached to an electronically driven hinge that controls the amount of colored light that is reflected from the mirror into the projection lens and onto a screen. Projection systems using DLP technology use 1 to 3 DMD devices.
DMD: Digital Micromirror Device. Name of the actual imaging chip used in a Texas Instruments DLP projection systems.
DNR: Digital Noise Reduction. A system that reduces picture noise by comparing previous frames to the present and smoothing out what appears to be noise to the algorithm. Helps reduce flickering in still parts of a video image.
DVI: Digital Visual Interface. DVI is a standard that defines the digital interface between digital devices such as projectors, flatscreens 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.
Front Projection: A system where the projector sits in front of the screen with the image getting reflected back to the audience.
Front Room Projector: A projector that sits close to the screen and is capable of throwing a large image.
Full On/Off Contrast: Contrast is the ratio between white and black. The larger the contrast ratio the greater the ability of a projector or flat panel to show subtle color details and tolerate extraneous room light. There are two methods used: 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 contrast ratio, make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for a given product.
Gamma: Relationship between input video voltage and output brightness. Determines how mid-tones appear as eye sensitivity is non-linear and display devices use different methods to account for this as well as their own display characteristics.
HDMI: HDMI (High Definition Multimedia Interface) is an uncompressed, all-digital audio/video interface that supports audio/video sources such as a set-top box, DVD player, A/V receiver, and video monitors such as a digital projector or digital television (DTV). HDMI is backward compatiable with DVI 1.0 specification and supports HDCP.
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio, and interactive controls on a single cable. It transmits all ATSC (Advanced Television Systems Committe) HDTV standards and supports 8-channel digital audio. First product releases using HDMI occurred in 2003.
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio, and interactive controls on a single cable. It transmits all ATSC (Advanced Television Systems Committe) HDTV standards and supports 8-channel digital audio. First product releases using HDMI occurred in 2003.
HDTV: High-Definition Television. Generic term that indicates a higher resolution format than previous standards. At present, denotes anything higher than a 480p signal. Most common formats are 720p, 1080i and 1080p.
HDTV capable: A television that supports 720p or 1080i or higher resolutions and has a built-in HDTV tuner for off-air reception of HD signals from a special antenna. To view cable and satellite HDTV programming, a cable set-top-box or satellite receiver is required.
HDTV ready: A television that supports 720p or 1080i or higher resolutions and does not have a built-in HDTV tuner for off-air reception of HD signals from a special antenna. To view cable and satellite HDTV programming, a cable set-top-box or satellite receiver is required.
High Gain Screen: A screen that uses one of many methods to collect light and reflect it back to the audience, which dramatically increases the brightness of the image over a white wall or semi-matte screen. Technologies used include curved screens, special metal foil screens (some polarized), and certain glass bead screens. High gain screens achieve higher brightness by directing more of the reflected light towards the center of the screen.
Horizontal Resolution: Amount of pixels across an image, from left to right. A 1920 x 1080 HDTV has a horizontal resolution of 1920 pixels.
LCD: Liquid Crystal Display. A display device for generating color images using a matrix of LCD pixel elements. Each pixel element consists of 3 sub-pixels and an RGB color filter of red (R), green (G), and blue (B). By controlling the voltage to each sub-pixel of an LCD, each cluster of RGB pixels can create a full spectrum of colored light. LCDs are used in flatscreen displays, cameras and notebook computers to name a few.
Nearly every projector made with LCD technology uses 3 separate LCDs, one each for red, green and blue. Light from the projector lamp is separated into RGB with a set of dichroic mirrors. The three light beams (RGB) are passed through separate LCDs and recombined to project a color image.
LCoS: Liquid Crystal on Silicon. Type of LCD panel that reflects light as opposed to blocking it. Usually offers a comparatively high fill rate creating a smooth image but generally has difficulty giving a high contrast ratio.
LED: Light Emitting Diode. A light generating technology that uses a semiconductor diode that emits monochromatic (single color) light when charged. LEDs are used in remote controls that are used to control electronic devices such as large displays. They are also used in pocket projectors as a light source, large outdoor electonic displays, and as indicators on electoronic devices such as power supplies and cameras.
Lens Shift: The Lens Shift feature of a projector allows the optical lens to be physically shifted up and down (vertical) and/or left and right (horizontal). Some lens shift mechanisms are motorized with vertical lens shift being the most popular. Lens shift will can avoid or minimize the need for keystone correction. It is also used to geometrically align images when stacking projectors.
Light Valve Projector: A projector that uses an imaging system that either blocks or reflects light such as LCD, LCoS or DLP.
Lumen: A measurement unit of total illumination. Typically a 100-watt light bulb outputs 1700 lumens over a wide area. Projector light output is measured in ANSI lumens. A projector with a higher lumen number will produce a brighter image for a given image size.
OLED: Organic Light Emitting Diode. A self-illuminating, energy-efficient, direct-view imaging system. Uses an organic film sandwiched between 2 transparent electrodes.
information.
information.
Projector: A projector is a device that integrates a light source, an 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. These devices attach to a computer or video device as you would connect a monitor or television.
QXGA: QXGA is a display resolution of 2048 horizontal pixels by 1536 vertical pixels giving a total display resolution of 3,145,728 pixels. A QXGA display has 4 times the resolution of an XGA display.
characteristic of sequential color systems with low refresh rates.
characteristic of sequential color systems with low refresh rates.
Rear- Projection TV: All-in-one display consisting of a translucent screen with a rear projector system.
Resolution: A measure of the ability of a display or sound system to render detail.
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. Considered a higher quality video source than composite video.
Screen Gain: As it applies to projectors, gain is the measurement of a projection screen’s light reflectance with unity gain being one. A high gain screen will reflect more light along a narrower path than lower gain screen. Screen gains under one use a gray screen to absorb ambient light to help maintain contrast ratios.
Screen Trigger: A 12V connection from a projector to an electric screen which tells the screen to deploy when the projector is turned on and roll up when the projector is turned off.
Screendoor Effect: An image distortion caused by digital imagers with a low fill rate. Looks like the picture is seen through a screen door with thin vertical and horizontal black lines and is commonly noticeable on lower resolution LCD displays. An LCD display fitted with a microlens array helps reduce this problem.
Shielded: A feature of speakers and cables where a metal layer is added to contain and protect a signal
Short Throw Lens: A lens designed to project the largest possible image from a short distance. Most front projection systems use a short throw lens and are required for rear projection where the depth behind the screen is limited.
cable and satellite services.
SVGA: SVGA is a display resolution measuring 800 pixels horizontally by 600 pixels verically giving a total display resolution of 480,000 individual pixels. SVGA has a 4:3 aspect ratio.
SXGA: SXGA is a display resolution measuring 1280 pixels horizontally by 1024 pixels vertically giving a total display resolution of 1,310,720 individual pixels. SXGA has a 5:4 aspect ratio.
TFT: Thin Film Transistor. A type of LCD display where each pixel is controlled by one to four transistors. TFT screens are sometimes called active matrix LCDs.
UXGA: UXGA is a display resolution measuring 1600 pixels horizontally and 1200 pixels vertically giving a total display resolution of 1,920,000 individual pixels. UXGA has an aspect ratio of 4:3.
from the bottom right of the screen to the top left after painting a field or frame.
from the bottom right of the screen to the top left after painting a field or frame.
VGA: VGA is a display resolution measuring 640 horizontal pixels and 480 vertical pixels giving a total display resolution of 307,200 individual pixels. VGA has a 4:3 aspect ratio.
Wi-Fi: Wi-Fi is Wireless Fidelity, and is a type of wireless network used to connect digital devices without the need for cables. It is mostly used for wireless broadband access and inexpensive consumer wireless antennas are available at electronics stores. There are four specifications currently in the family: 802.11, 802.11a, 802.11b, and 802.11g.
Wi-Fi (802.11a): An IEEE specification for wireless networking that operates in the 5 GHz frequency range (5.725 GHz to 5.850 GHz) with a maximum 54 Mbps data transfer rate. The 5 GHz frequency band is not as crowded as the 2.4 GHz frequency, because the 802.11a specification offers more radio channels than the 802.11b. These additional channels can help avoid radio and microwave interference.
Wi-Fi (802.11b): International standard for wireless networking that operates in the 2.4 GHz frequency range (2.4 GHz to 2.4835 GHz) and provides a throughput of up to 11 Mbps. This is a very commonly used frequency. Microwave ovens, cordless phones, medical and scientific equipment, as well as Bluetooth devices, all work within the 2.4 GHz frequency band.
Widescreen: Any aspect ratio that is wider than 4:3. Widescreen televisions are 16 units wide and 9 units tall. Common widescreen film aspect ratios are 1.66:1, 1.85:1 and 2:35:1.
WSXGA: WSXGA defines a class of SXGA displays with a width resolution sufficient to create an aspect ratio of 16:9. A WSXGA display has 1920 to 1600 pixels horizontally and 1080 to 900 pixels vertically.
WXGA: WXGA defines a class of XGA displays with a width resolution sufficient to create an aspect ratio of 16:9. Resolution is defined by the number of pixels that a display uses to create an image. A WXGA display has 1366 to 1280 pixels horizontally and 768 to 720 pixels vertically.
XGA: XGA is a display resolution measuring 1024 pixels horizontally and 768 pixels vertically giving a total display resolution of 786,432 individual pixels. XGA has a 4:3 aspect ratio.
Y/Cb/Cr: Digital component video. Y stands for the luma signal itself and Cb is the blue signal subtracted
Zoom Lens: A lens with a variable focal length providing the ability to adjust the size of a projected image without moving the projector or provide a range of projector placements that can produce the same size image.
Zoom Ratio: Is the ratio between the smallest and largest image a lens can projector 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 a 10 image at 21 feet at maximum zoom (15 x 1.4 = 21 feet). A zoom lens is "not as bright" as a fixed lens, and the higher the ratio, the less light output.
