A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
– A –
Aliasing: Jagged edges along the outer edge of objects or text. Anti-aliasing refers to software adjustments that correct this effect. This effect is created by inadequate sampling techniques in computer-produced images.
Alpha Channel: The transparent channel of an image file. The Alpha channel can be manipulated with projection software to alter it’s color or transparency. Alpha channel data is also useful when layering projected images on top of one another.
Ambient Light: Light from sources other than the projector. Stage light, room light, and exit signs all provide ambient light. A successful projected image requires a projector bright enough to overcome the ambient light present in the room.
Analog: An analog color video signal contains black, white, brightness, and color information of an analog television image. When combined into one channel it is called composite video.
ANSI Lumens: ANSI stands for American National Standards Institute. It is a standard for measuring light output. Different lamps play a role on light output. Halogen lamps appear dimmer than another metal-halide, even if the two units have the same ANSI lumen rating. Type of LCD technology (active matrix TFT, Poly-Si, passive), type of overall technology (LCD vs. DLP vs. CRT), contrast ratios, among other factors can also affect the end result.
Aspect Ratio: The numeric relationship between a screen’s height and width. This ratio is often defined by the selected projection medium.
Auto Adjust: Setting on some projectors to automatically adjust the projector to the signal that is being sent to it. While useful in some settings it may need to be turned off if using mapping software. The mapping software can send a signal to the projector that would cause it to adjust to the wrong aspect ratio, which may cause the projected image map to appear off from the intended area.
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– B –
Balun: an electrical device that converts between a balanced signal (two signals working against each other where ground is irrelevant) and an unbalanced signal (a single signal working against ground or pseudo-ground). (from Wikipedia) Can be used as a part of a video extender device to cary digital video signals over long distances.
Bandwidth: The frequency range of a particular transmission method. In video systems, this value is expressed in MHz, and the better the signal, the greater the bandwidth required.
Bézier Curve: a parametric curve used by a computer to smooth a curve. Mapping software uses this curve to allow for mapping on to spherical or curved shapes.
Bit Mapped Graphics: The type of graphic that is defined and addressed on a bit-by-bit basis which makes all points on the screen display directly accessible.
BNC: (Bayonet Neill Concelman) Named after inventors Paul Neill & Carl Concelman. Used with coaxial cables, this connector receives all R, G, B, H-Sync and V-Sync information, and composite video.
Brightness: The perceived or quantified amount of luminance produced by a projector or reflected off of a surface. Projectors measure brightness in lumens.
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– C –
Camera: a device for capturing moving images and communicating the images into the computer. Some software allows for a camera input to allow live video to be used as projection content.
Cat 5/6: a twisted pair computer networking cable which uses 8P8C modular connectors. Inexpensive cable that can be used to create a private network between two or more computers.
Chrominance: Also known as Chroma, the color component of a video signal.
Codec: Standing for coder-decoder, a codec is a piece of software that allows a computer to decode or decompress a video or audio file, play it, and compress or encode video to a specific file type.
Color Resolution: The total number of colors available, expressed in bits per pixel.
Color Temperature: A method of measuring the “whiteness” of a light source. Metal halide lamps produce higher temperatures than halogen or incandescent lights.
Component Video: An analog video signal that has been broken down into 2 or more separate signals.
Composite Video: (CVBS) An analog video signal where all of the signal data is carried in one line level signal. Cable TV is an example of a composite video signal.
Container File: A media file which contains compressed audio and video data. Container file formats can support multiple video and audio file formats and can occasionally be misleading since two files with similar file extensions may require different codecs or players to be able to be played back.
Contrast Ratio: The ratio between brightest and darkest portions of a projected image. Projectors that are able to produce a higher difference between white values and black values create a clearer image with more subtle colors and shading.
Corner Pin: a feature in projection mapping software that allows the user to manipulate the four corners of a projection map to conform the map to the physical projection surface.
CPU: (Central Processing Unit) is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output operations specified by the instructions. The speed and power of a computers CPU may create a limiting factor in processing large amounts of video and projection mapping data.
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– D –
Diagonal Screen: One corner of a screen to the opposite corner. A 9FT high, 12FT wide, screen has a diagonal of 15FT. If the screen is 12×12, it would still rate 15FT diagonal since that would be the diagonal usable.
Digital: The way in which computers experience information. Computers see every piece of information passing through them as 1’s and 0’s. Complex images can be broken down into small pieces (bits) and those pieces can be defined as a series of on (1) and off (0) codes.
Display Port: A digital display interface. A connector and cable capable of carrying a digital signal from a computer to a display. Display port can also carry information for multiple displays, audio signals, data, network information, and power. Apple’s Thunderbolt port utilizes a mini display port connector.
Dithering: Making digital images appear smoother by adding color or random noise during the digitization process.
DLP: (Digital Light Processing) Developed by Texas Instruments, DLP is a light processing system that utilized hundreds of thousands of tiny spinning mirrors to reflect images. Many feel it is the most accurate reproduction of color and images available today.
DMX: (Digital Multiplexing) A computer communication standard used by lighting consoles to exchange information with dimmers, intelligent lighting fixtures, and other stage machinery. Some show control software can communicate with lighting consoles in DMX.
Dowser: A physical barrier placed over the lens of a projector or between the lamp and the lens of a projector to block the light output from the projector. A dowser is often used to block all light from a projector during a blackout of stage light.
DVD: (Digital Video Disk) An optical disc data storage format used to store video information. The DVD format can store 4.7 gb of information in a single layer, some discs are double layer discs and can store 8.5 gb of information. Consumer DVD movies are limited to a resolution of 720×480. The same size discs are now used with the newer Blue Ray standard which allows for video with resolutions up to 1920×1080 and storage capacities of 25 gb for single layer and 50 gb for dual layer.
DVI: (Digital Visual Interface) Signal used to carry video between a computer and a display or projector. Can carry analog or digital signals. Can have one of three
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– E –
Edge Blending: A process that video mapping software uses to dim the portions of two or more projected images that overlap to produce a single seamless image.
Extender: A device which allows a video signal to be transmitted over a longer distance than a single cable will allow. Extenders range from signal amplification to encoding and decoding the original signal.
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– F –
File compression: The process of applying an algorithm to an image, audio, or video file to remove unnecessary information and make the file size smaller.
Firewire: A high speed input/output protocol used for rapid transfer of data between devices.
Flash Memory: A data storage method which requires no moving parts. Information is stored when written to the device and remains stable until written over.
Focal Length: Focal length is the distance between the lens and its focal point. A smaller focal length indicates a wider-angle lens.
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.
Frame Rate: The rate at which a device or video file plays or stores individual frames of video. Listed as frames per second (fps) Common rates are 24 fps or 30 fps.
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– G –
Gain: A measurement usually made perpendicular to screen center of the luminance transmitted by the screen, divided by the luminance radiating from the projector. Also can be described as the screens ability to gather light.
Gamma Correction: An adjustment of the brightness and contrast of a video output signal from a computer. Adjusting the Gamma of the output signal will allow an image to appear the same on an external monitor or projector as it does on the main display. Gamma adjustment can make an image appear brighter and crisper without appearing washed out.
Ghosting: A shadow or weak secondary image as seen on a monitor or display which is created by multiple path broadcast transmission errors.
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– H –
HDD: (Hard Drive Disk) Also known simply as Hard Drive. A data storage device for computers. Generally store data magnetically on disks which spin at a high rpm. Hard drives with higher transfer rates are desirable because a computer can access and process data faster.
HDMI: (High Definition Multimedia Interface) A digital multimedia interface used by many audiovisual devices. Capable of transferring audio and video signals on the same cable/connector. Video resolution is only limited by the bandwidth of the cable.
HDTV: Acronym for High Definition Television
High Definition: Video signal with a higher resolution than standard definition. Generally any video signal with a resolution higher than 720×480 is considered high definition.
High Gain Screen: A screen that uses one of 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.
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– I –
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 is not also upside down.
Isadora: A node based graphic programing software that was developed specifically for the performing arts. Isadora was created by Mark Coniglio.
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– J –
JPEG: (Joint Photographic Experts Group) A lossy format for digital image compression. Used on digital image files to reduce file size. A higher compression ratio reduces the file size more and degrades the quality of the original image.
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– K –
Keystone: The distortion of the projected image when the screen is not perpendicular with the center line of the projected image.
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– L –
Lamp: The light source inside of a projector or lighting instrument. Projector lamps are often expensive and require special handling to prevent damage. Projector brightness is often created with multiple lamps.
Layer: Used in video editing and playback software to mix images. Layers can occur over one another or blend with a host of controllable properties. While most software supports using multiple video layers at the same time the process is very taxing on the computer. Often the computer will slow down as more layers are added.
LCD: (Liquid Crystal Display) This technology comes in many forms, sizes, and resolutions. Its primary purpose is to present a digital image for viewing. They are used in many notebook computer displays and also used as technology inside a projector to project high-resolution digital images.
LCoS: (Liquid Crystal on Silicon) New technology which which combines the benefits of LCD and DLP technologies. Essentially an LCD on top of a mirror. LCoS is capable of higher pixel densities than LCD or DLP displays.
LED: Light Emitting Diode.
Lens: The optical component in a projector that transmits the image to the screen. Lenses are available in a variety focal lengths which allow a projector to be placed close to a screen or far from the screen while maintaining a similar sized projection area.
Lens Shift: A feature on some projectors that allows the projector to move the lens left, right, up, or down to help make a small adjustment of the projected image without moving the entire projector. Helpful when adjusting projectors which are stacked to increase brightness.
Lenticular: A screen surface that has 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 a projection booth in the back of a theater, or from the back of a large classroom.
Luma: The brightness of the black and white component of a video signal.
Lumen: a measure of the total amount of visible light emitted by a source.
Luminance: The measured brightness of a screen, expressed in foot-lamberts.
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– M –
Madmapper: Software manufactured bu Garage Cube, which allows for mapping a projected image on to 3 dimensional surfaces.
Mapping: A process of using computer software to alter a projected image to conform to surfaces that are not flat or square.
Masking: A process of using computer software to black out a portion of a projected image to prevent the image from unintentionally “spilling” onto adjacent surfaces.
MATROX: Manufacturer of multi-out external graphics cards. Allows for expanded outputs from one computer display port.
Media Server: Any device capable of storing and playing back audio and video. DVD players, computers, and even tablets can be used as media servers. If multiple outputs are required media servers require faster processors to function.
Mesh warp: A feature of some mapping software which treats the projector output as a mesh or grid which can be manipulated through the software to bend around corners or adhere to a rounded surface.
Metal Halide Lamp: The type of lamp used in most high-end portable projectors. These lamps output a very “hot” temperature light, similar to lamps used in streetlights. Metal Halide whites are super white (with a hint of blue) and make Halogen lamp white very yellowish by comparison.
MIDI: Musical Instrument Digital Interface. Used as a communication protocol between devices that have a MIDI port. Simple communication of on/off is the most common communication.
Mini Display Port: Apple form of low-profile video out. Thunderbolt adapters are backwards compatible to this format.
Mirroring: To send the same signal to local and remote monitors.
Multiple Display Adapter: A device which allows a computer with a single video output to expand the single output to use 2 or 3 output devices. See MATROX.
Multiplexing: The condensing of many signals into a few or one signal that still represents all of them. 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.
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– N –
Network: Allows two or more computers to exchange information quickly and easily.
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– O –
Opacity: A measure of the transparency of an image. Software may use opacity to create a fade in and fade out effect when introducing an image. Opacity data can also be stored in an images Alpha channel. This will allow that image to have transparent and opaque regions and will allow images layered under them to be visible through the transparent regions.
OSC: Open Sound Control. A protocol for computers to communicate with other multimedia devices. Some show control software will use OSC to communicate with digital sound mixers, synthesizers, and other devices to control multiple devices from one source.
Overlay: The capability to superimpose computer-generated graphics and/or text on motion or still video.
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– P –
Pixel: Short for picture element. The smallest element in a displayed image. 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).
Pixel Density: A measurement of the number of pixels within a given area. See also Resolution. Pixel Density can be measured in PPI (Pixels Per Inch) or for printing DPI (Dots Per Inch)
Poly-Si (silicon) LCD: A popular LCD technology for the top of the line LCD projectors, which results in increased color saturation, with contrast ratios above 200:1.
Power Zoom: A zoom lens with the zoom in and out controlled by a motor, usually adjusted from the control panel or a remote control. This is as compared to Digital zoom, which does this same function Digitally.
Projection Axis: The direction of an imaginary line extending from the center of the projection lens through the screen’s center.
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– Q –
Qlab: Cue based show control software made by Figure 53. Qlab is used for sound and projection design to organize and implement designs. Qlab can interface with lighting and sound consoles to allow users to control multiple production elements from one computer.
Quartz Composer: A node based computer programing language for processing graphical data. Quartz composer runs on Mac OS and allows users to create their own graphics processing programs. Some projection software will allow users to use their Quartz Composition files to alter the projected image.
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– R –
RAM: (Random Access Memory) The working memory of a computer system. A computer will move information into the RAM to be able to process it then will either save it to a hard drive or export the data to a display. Some software will allow you to pre-load large files into RAM to speed up the process of working with the file.
Raster Graphics: The process with which the majority of graphics are stored and displayed in a computer environment. The image is divided into a grid of pixels and data is stored about each pixel.
RCA connector: The connector used with VCRs and stereos for composite video signals and audio. RCA refers to Radio Corporation of America. Also, sometimes called an AV (Audio/Video) or phono (for phonograph) connector.
Real Time: The transfer of data that returns results so quickly that the process appears to be instantaneous.
Rear Projection: Projecting an image through a translucent screen material for viewing from the opposite side. This method of projection is also an option for home theater use in large spaces.
Render: The process of a computer generating an image from an image model or image file. The computer takes geometric, physical, and lighting data in and generates an image to a display. Projection software adds position, mapping, and edge blending data to this as well. The process of rendering an image can be taxing on the processor if there is too much data to process. Simplifying the requirements of the image may allow it to render faster.
Resolution: Number of pixels (or dots) per unit of area, measure in number of pixels wide by the number of pixels high that can be displayed on the screen or monitor. More pixels per unit of area produce a higher resolution.
RGB: Red, Green, and Blue. Refers to the mixing of red, green, and blue subpixels in a display to create color. Also refers to a type of analog signal in which the three color signals travel on separate channels between the computer and the monitor or projector.
RS-232C: A serial signal that computers and electronic equipment use to communicate and exchange data.
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– S –
SATA: (Serial ATA) Serial Advanced Technology Attachment. An interface used to attach a hard drive to a motherboard. An SATA hard drive will have a significantly higher data transfer rate than a non SATA hard drive.
Screen: Projection screen or surface. Screens come in several shapes, sizes, textures, and are made with different types of materials. Screens are designed to be projected on the front or the back and are optimized for various lighting conditions.
SSD: (Solid State Drive) A data storage device similar to a hard drive. A SSD drive does not have moving parts and does not store data magnetically. A SSD stores data as flash memory and can retrieve data faster than a conventional hard drive. The faster retrieval rate is attractive to projection design systems since it speeds up the throughput of data in the system.
Surface: A designation in Qlab software for a virtual video output for projected data. One or more projector can be attached to a surface. A surface can then be mapped onto a screen or set.
SVGA: (Super Video Graphics Array) Analog signal used to carry video between a computer and a display. Original resolution 800×600.
S-Video: Separate Video, Super Video, Split Video, or Y/C, an analog video signal which separates the black and white, and color portions of the video signal. Maximum resolution is 720×576.
SXGA: (Super Extended Graphics Array) Analog signal used to carry video between a computer and a display. Original resolution 1280×1024.
SXRD: (Silicon X-Tal Reflective Display) Sony’s proprietary liquid crystal on silicon (LCoS) display system. Used in their high end projectors, capable of achieving 4K resolution.
Syphon: Open source software for Mac OS which allows applications to share video data.
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– T –
Test Pattern: An image with a pattern of colors and black and white squares that can be used when setting up a projector. The pattern can be helpful when adjusting brightness, contrast, and color data. Grid like patterns can be useful when focusing a projector onto a surface.
TFT: (Thin Film Transistor) A technology used to make Active Matrix LCD panels wherein each pixel has its own transistor switch.
Throw Distance: The length of the projection beam necessary for a particular projector to produce an image of a specified size.
Throw Ratio: The ratio of the distance between the projector and the screen and the screen width. The ratio is determined by dividing the distance to the screen by the screen width. This information is helpful in determining projector location and lens selection.
Thunderbolt Port: An input-output (I/O) port primarily used on newer Apple computers. The port utilizes a mini-display port connector and supports high speed transfer of data. On newer machines the port can replace firewire, video output, audio input-output, and network specific ports. The Thunderbolt protocol allows for a faster transfer of information than firewire or usb.
Timecode: A series of numeric codes that different pieces of equipment can use to synchronize their operations. A timecode is typically generated by one machine or piece of software and then transmitted to other machines or software which follow the timecode.
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– U –
USB: (Universal Serial Bus) Refers to the communications protocols, connectors, and cables used by computers to connect to a wide array of devices.
UXGA: (Ultra Extended Graphics Array) Analog signal used to carry video between a computer and a display. Original resolution 1600×1200.
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– V –
Vector Graphics: Computers can use geometric primitives to store and display graphical information. The computer will use points, lines, shapes, curves and polygons to represent an image. Information on color, shape, thickness, and fill of the primitives is also stored.
Video Black: The brightness of a projected image that is all black. Since projectors always produce light to project an image light is produced to project a black image. This projected light must be considered and dealt with when using video projectors in a theatre. When all of the stage lights black out projectors will often need to have a dowser to completely block the lens so that no light can be projected onto the stage.
Video Card: An expansion card that can be installed in a computer to help speed up the processing of video data. Sometimes called a graphics accelerator.
Video Ram: (VRAM): Video Random Access Memory. VRAM is a component of a computer video card which acts as a buffer between the system processor and the video output. Images are processed through the system processor and written to the VRAM. Systems with video cards with higher amounts of VRAM are better able to process large amounts of video data without slowing down the system or lowering the quality of the video output.
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.
VGA: (Video Graphics Array) Analog signal used to carry video from a computer to a display or projector. Original resolution was 640×480 but VGA can now carry a high definition signal.
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– W –
WXGA: (Wide Extended Graphics Array) Analog signal used to carry video between a computer and a display. Original resolution 1366×768.
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– X –
XGA: (Extended Graphics Array) Analog signal used to carry video between a computer and a display. Original resolution 1024×768.
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– Y –
Y/C Connector: A 4-pin DIN connector used for high-end S-video sources. Y carries the luma or luminance signal and C carries the chroma or chrominance signal. Both Y and C are paired with a ground wire.
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– Z –
Zoom Lens: A lens with a variable focal length. This translates to being able 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.