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Document Camera Glossary

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Document Camera Terms - A

Document Camera Aliasing
When images from a document camera are rendered on a screen, sometimes jagged edges can be see along the outer edges of text and objects. This is caused by inadequate sampling techniques when a document camera’s image is reproduced by a computer. Document camera anti-aliasing is a software adjustment which corrects this jagged edge effect.
Document Camera Active Pixel Sensor (APS)
A document camera’s Active Pixel Sensor is a type of image sensor that contains pixel sensors with a photo detector that connects to a transistor readout and reset circuit. CMOs and CCDs are two typical types of document camera image sensors.
Ambient Light
Ambient light is any type of light that is emitted in the room where the document camera is being used, other than light produced by the document camera and projector or other display device.
ANSI is an abbreviation which stands for the American National Standards Institute. ANSI Lumens is a standard for measuring light output and is used for comparing projectors.
Active Matrix LCD
An active matrix LCD is a solid state device which can control every pixel in a display device to produce a very high quality image.
Amp or Amplifier
An amp or amplifier is a device than can be used along side a document camera to amplify either an audio or a video signal.
Document Camera Aspect Ratio
Aspect ratio is a term used to describe the height and width of the image displayed on the screen from the document camera. For example in a 16:9 document camera aspect ratio, the width of the image is 16/9 times the height. In any document camera aspect ration the first number is always the width, followed by the height.
Document Camera Audio In
Audio in is an input audio connection for a document camera. This type of document camera connection is usually a female RCA jack.
Document Camera Audio Out
Audio out is a document camera output connection used to carry an audio signal from the document camera to another device. This type of document camera output connection usually uses a female RCA jack.

Document Camera Terms - B

Backlit document camera accessory
A backlit document camera accessory is a device that is illuminated from behind, for example in some document camera remotes.
Bandwidth is a measurement of the rate of data transfer and is measured in bits per second.
Barco N.V.
Barco (which originally stood for Belgian American Radio Corporation) is a manufacturer of display devices which could be used with a document camera. Barco specializes in displays such as DLP and LCD projectors, flat panel televisions, LED displays and display walls.
Baud Rate
Baud rate is a data transmission speed. For example, 56K baud is 56,000 bits per second.
Bit map is a graphics format which a document camera might use where an image is defined on a bit by bit basis. This makes all points on the screen display directly accessible.
Is a graphics format that is defined on a bit-by-bit basis which makes all points on the screen display directly accessible.
BNC Document Camera Connections
Document cameras using either composite video cables or coaxial cables receiving R, G, B or horizontal sync. information, will most often have BNC terminators at the ends of these cables.
Build Slide
"Build series " slides can be used by presenters using a document camera to show audiences where their presentation is heading a line at a time. Each new line of information added to the presentation is highlighted in a bright color while the previous line changes to a darker color.

Document Camera Terms - C

CCD Document Camera Image Sensors
A charge coupled device, or CCD, is a type of document camera image sensor. CCD document camera image sensors are made up of an integrated circuit which contains an array of coupled, light sensitive capacitors.
CMOS Document Camera Image Sensors
CMOS, which stands for complementary metal oxide semiconductor, is a class of integrated circuit technology which is often used in document camera image sensors, highly integrated transceivers and data convertors as well as in chips such as static RAM, and microcontroller’s microprocessors.
Composite Video Document Camera Connectors
Composite video connectors are typically used to connect document cameras to analog displays. The composite video document camera connector is usually a yellow connector which is often found coupled with red and white audio connectors. Composite video is usually in standard format such as PAL, NTSC and SEECAM.
Compressed Document Camera Resolution
Compressed resolution is a method which might be used to reduce the resolution of a document camera’s signal to enable it to be used on a lower resolution display  device. The downside of compressing a document camera’s resolution is that the document camera’s image quality is reduced.
Document Camera Confidence Monitor
Document camera confidence monitors are small LCD monitors ranging from three inches to six inches in size. A document camera’s LCD confidence monitor allows the person using the document camera to see the image that will be displayed before it is displayed on the projection screen, television or computer. This allows the person using the document camera to check that the image is in the correct position and properly focused.
Document Camera Contact Image Sensors (CIS)
Contact Image Sensors (CIS) are a new type of document camera technology that is quickly replacing the CCD type image sensors in low power portable document cameras. A document camera contact image sensor is normally made up of focusing lens which covers a linear arrangement of light detectors. Illumination is provided by red, green and blue LEDs around the light detectors and lens. In general document cameras with CIS image sensors produce a lower image quality to document cameras with CCD devices.
Display device contrast ratio
The contrast ratio of a display device being used with a document camera is the ratio between the darkest images the display device can reproduce and the lightest images. A display device with a higher contrast ratio is better able to show subtle color details produced by the document camera and can display clearer images in environments with ambient light.

There are two ways to measure the contrast ratio of display devices which will display document camera images. The ANSI method of measuring contrast ratio uses an arrangement of sixteen alternating black and white rectangles. Full on/off contrast ratio is a measure of the ratio of light when the light output is completely black (off) and when it is completely white (on).

Cathode Ray Tube (CRT)
Cathode ray tube monitors (also called tube TVs) are an older type of display device which are increasingly being replaced by LCD and plasma flat panel television screens.

Document Camera Terms - D

DAT is an abbreviation for digital audio tape recorder/player
Decibel (db)
The decibel is a unit used to measure the strength of electronic sound signals.
Desktop Videoconferencing
Desktop videoconferencing is a videoconferencing session using a personal computer
Digital Light Processing (DLP)

Digital Light Processing (DLP) is a technology used in projectors which could project an image from a document camera. DLP technology was originally developed in 1987 by Dr. Larry Hornbeck at Texas Instruments. If an image from a document camera is projected on a DLP projector, the image from the projector is formed by thousands of tiny mirrors which each represent one pixel. The mirrors are positioned in a matrix on a semiconductor chip which is known as a Digital Micromirror Device (DMD). The number of mirrors on the DMD is representative of the resolution of the projected image, for example 800 pixels by 600 pixels, or 1024 pixel by 768 pixels.

Digital presenter
A digital presenter is another phrase used to describe a document camera or visualizer.
Document camera
Document cameras are the latest electronic imaging devices which can be used to display pages from a book, transparent overhead slides or three dimensional objects. Digital presenter and visualizer are other terms which mean the same thing as a document camera.

Document Camera Terms - E

Epidiascope visualizer
An epidiascope is an early version of an overhead projector, and an even earlier version of a digital presenter or visualizer. The epidiascope is often referred to as the opaque projector because it functions to display opaque materials by producing a bright light from above, and then uses a sequence of prisms and mirrors to focus the final image. An epidiascope will usually require a brighter bulb and a bigger lens than an overhead projector to enable it to project the reflected light.
An equalizer, or EQ as it is normally called, is a type of audio device which uses a number of frequency controls in order to manipulate the tone quality of sound signals.

Document Camera Terms - F

Document Camera Focal Length
Document camera focal length is the distance from the document camera’s lens to the focal point of the subject matter that the document camera is viewing. When the document camera’s lens is very close to the subject, a wider viewing angle must be used.
Front Projection
A document camera’s image could be displayed on a front projection device. This is a display device where the image is displayed by emitting light from the front of the screen on to the display surface. Front projection display devices are typically use LCD or DLP projection technology.

Document Camera Terms - G

Document Camera Genlock

When two video sources are synchronized it is termed genlock. Genlock is very important when a presenter is trying to overlay graphics from a computer on an image from a document camera, VCR or videodisc player.


When there are multiple path broadcast transmission errors, a weak secondary image or shadow is sometimes displayed in addition to the main image. This is termed ghosting.

Graphical User Interface (GUI)

A graphical user interfaces allow presenters to interact more easily with computers or other types of media devices which use graphical images, for example document cameras. A graphical user interface usually consists of special graphical element devices as well as text which combine to show the presenter which actions and information are available to them. The user can then execute these actions by manipulating the graphical elements.

Document Camera Terms - H

H Sync
H Sync is an abbreviation which stands for horizontal synchronization. H synch functions as an indicator to tell the computer or video signal that it is the start of a line.
Hand Held Microphone
A hand held microphone is a microphone that could be used alongside a document camera in a presentation. These types of microphones can be either hard wired or wireless, and can be either attached to a stand or lectern or held by hand or attached to a stand or lectern.
High Definition Television (HDTV)
HDTV is a abbreviation for High Definition Television. Document camera images could be displayed on a high definition monitor or projector.
Hertz (Hz)
Hertz is a unit of measurement for frequency. 1,000 Hz is equal to 1,000 cycles every second.
High Gain Screen
A high gain screen is a type of screen which could be used to display an image form a document camera. High gain refers to a high level of image brightness on a typically white wall or a semi-matter screen. A high gain screen uses a variety of methods in order to collect light and reflect it back to people viewing the images from the document camera.

Document Camera Terms - I

Document Camera Image Sensor

A document camera’s image sensor is the device inside the document camera’s mechanics that converts the image that the document camera sees into an electronic signal. A document camera’s image sensor normally consists of an array of charge-coupled devices (CCD) or complementary metal oxide semiconductor (CMOS) sensors, for example active pixel sensors. Image sensors are also used in digital cameras and other imaging devices.

Inverted Image

If the projector you use to display your document camera’s image is mounted on the ceiling, it is likely that it will be fixed upside down. Projectors have inverted image features to turn the document camera’s image around so that it is displayed the right way up on the screen.

Interactive Whiteboard

Interactive whiteboards can be used in combination with a document camera during a presentation, and they are becoming increasingly more popular in classrooms and boardrooms around the world. A document camera coupled with an interactive white board is an excellent means of displaying interactive images and information. An interactive white board is typically used as an interactive computer screen – the image from a document camera can be annotated and manipulated by the presenter by touching the interactive whiteboard.


ISDN is an abbreviation for Integrated Services Digital Network.

Document Camera Terms - J

JPEG is an image format which could be saved from a document camera. JPEG stands for Joint Photographic Experts Group.

Document Camera Terms - K

An image from a document camera projected by a projector could suffer from keystone distortion, also called trapezoid distortion. This can happen if the bottom of the projection screen is at a higher level than the projector. If your document camera image experiences keystoning it should not be a problem since most new model projectors have a feature to correct this problem.
Kilohertz (Khz)

Kilohertz is a unit of measurement for frequency. 1Khz is equal 1,000 cycles every second.

Document Camera Terms - L

LCD Projection Panel
An LCD projection panel is a flat panel display device which uses liquid crystal display technology. An LCD projection panel could be used to display an image from a document camera.
Light Valve Projector
Light valve projectors are a type of projector used for displaying images on theatre sized screens. Light valve projectors are able to do this since they are capable of displaying very large images, and they are very bright.

The lumen (abbreviated to lm) is a measure of luminous flux – a standard of measurement of the perceived power of light. Lumens can be used to measure the power of a projector showing an image from a document camera. Luminous flux is a different measurement to radiant flux because a measurement of luminous flux is adjusted to take into account the varying sensitivity of the human eye to varying wavelengths of light. Radiant flux simply measures the total power of light emitted by the projection device.

Luminance is a measure of the intensity of light produced in a given direction. Luminance measures the amount of light that is emitted from or which passes through a particular area, falling inside a set solid angle.

Document Camera Terms - M

Megahertz (Mhz)
Megahertz is a unit of measurement for frequency. 1Mhz is equal to 1,000,000 cycles every second.
Metal Halide Lamp
A metal halide lamp is a type of projector lamp which could be used in a projector to produce the light needed to display a document camera image. Metal halide is the type of lamp that is used in the majority of higher end portable projector models. Metal halide lamps are able to produce an extremely white light that has a hint of blue in it, which can make halogen lamps look a yellowish color in comparison.
A mixer is a piece of audio visual equipment used to combine and adjust a number of signals from a variety of audio and video sources, for instance the audio signal from a microphone and the video signal from a document camera.
A monitor can be connected up to a document camera. The term monitor usually describes cathode ray tube televisions or computer video displays.
Document Camera Multimedia
Multimedia is one of the key benefits of using a document camera. It is media that brings together a variety of different types of information content and processing, for example, video and graphics from a document camera, annotated text and audio. Multimedia from document cameras helps to inform and entertain audiences.

Document Camera Terms - N

Networked Document Cameras
A document camera can be connected up to a network, which is usually described as a computer network which links two or more computers and peripherals together. This enables computers on the network to share the images and information from a document camera.

Document Camera Terms - O

Document Camera Optical zoom
Document cameras with optical zoom functionality have a zoom lens which is controlled by a motor. The document camera’s optical zoom is normally adjusted using the document camera’s control panel or its remote control. Document camera digital zoom is different since it does the same function digitally.
Overhead Projector
Overhead projectors (or OHPs) are essentially early predecessors of document camera technology. Overhead projectors are limited in their functions because they can only use transparencies to display an image. Document cameras can display transparencies, opaque documents and even 3D images to an audience.
Document Camera Overlay
Overlay is a technique that can be used to superimpose text or computer generated graphics on a still image or video captured from a document camera.

Document Camera Terms - P

Parallel Port
A parallel port is used to connect a variety of peripherals to a computer. An example of a peripheral which might use a parallel port connection is a computer printer.
Pixels are used to form an image from a document camera on a display device. Each pixel represents a single point on a graphical image and is an abstract sample rather than a square point. If an image from a document camera is not reproduced properly, for example if the resolution of the display device is not good enough, pixels can become visible as squares or dots.
Plenums are enclosed spaces in buildings which are frequently used for heating, air conditioning and ventilation. Cables may need to be run through these spaces, in which case this cabling must be plenum rated, meaning that the cables are enclosed with slow burning, fire resistant casing to meet building regulations.
Poly-silicon LCD
Poly-silicon LCD technology is used in very high end projectors which could be used to display graphics and images from a document camera. Poly-silicon LCD projectors have contrast ratios of 200:1 and higher, and also show increased color saturation properties.
Document Camera Power Zoom
Document camera power zoom is the same as document camera optical zoom - a zoom lens that is controlled by a motor using the document camera’s control panel or the document camera remote control.
Progressive Scan
Progressive scan is a video output format which outputs data sequentially as it is scanned by the display device. Progressive scan video format outputs a continuous, full frame video.

Document Camera Terms - R

RCA/Phono Document Camera Connector
RCA jacks are a variety of cable connectors which are often used to terminate document camera composite video and stereo audio cables. RCA connectors (derived from the name Radio Corporation of America, which introduced the design in the early1940s) are also called phono connectors or CINCH/AV connectors.
Rear Projection Screen
Graphics and video from a document camera can be projected on to a rear projection screen. Rear projection screens are display devices where a document camera’s image is projected on to a translucent screen from behind.
Remote Mouse and Keyboard Control
Remote mouse and keyboard control means that a presenter can use a computer with their document camera without needing to access the computer directly. This means that the presenter is not restricted and can move freely about the classroom.
Document Camera Resolution
Document camera resolution refers to the total number of pixels in the maximum screen viewing area. Typical document camera resolutions are 800 pixels by 600 pixels (SVGA resolution), 1024 pixels by 768 pixels (XGA resolution) and 1280 pixels by 1024 pixels (SXGA resolution).
RGB is an abbreviation for the three primary colors of light: Red, Green and Blue. These three colors are the basic components of light which make up the image on any display device.
RS-232 is a telecommunications standard for serial binary data interconnection between data terminal equipment (DTE) and data circuit-terminating equipment (DCE). RS-232C is often used in computer serial ports. A similar ITU-T standard is V.24.

Document Camera Terms - S

Scan Rate
A display device’s scan rate is calculated by the speed of the vertical and horizontal and lines. Scan rates are most frequently quoted in Hertz or Kilohertz.
Scanning in a display device is the electronic process of moving a beam of electrons across a cathode ray tube device’s surface.
SECAM is a type of television standard. It is the TV system used in many Eastern European countries and also France.
Serial Port
A serial port is an input or output connection on a computer that is used to send out data one bit at a time. A mouse is an example of a peripheral which uses a serial port.
Slide View Box
A slide view box is a device which contains a translucent panel and a source of illumination. A slide view box is used to sort through 35mm and 2"x2" slides before viewing them on a projection screen with a slide projector.
Sync Synchronization
Sync synchronization is the process where scanning signals keep the video display generator locked to the appropriate source.
SVGA Document Camera Resolution
SVGA document camera resolution stands for Super Video Graphics Array. This type of document camera resolution displays in 800 pixels by 600 pixels.
SXGA document camera resolution stands for Super Extended Graphics Array. This type of document camera resolution uses 1280 pixels by 1024 pixels to display images.
Super Extended Graphics Array. Resolution = 1280x1024 pixels

Document Camera Terms - T

Telephone Interface
A telephone interface is used to connect a telephone line to a sound system in order for many people to be able to hear audio properly in a large conference call.
TFT-LCD stands for Thin Film Transistor-Liquid Crystal Display technology. This is a kind of active matrix liquid crystal display and is identical to LCD. Thin-Film Transistor technology improves the quality of the displayed image in both LCD projectors and flat panel LCD displays, both of which can be used to display graphics and video from a document camera. TFT LCD monitors are continually replacing older cathode ray tube technology computer monitors.
Throw Distance
A projector’s throw distance is the required distance between the projector and the screen in order for the projector to display an image of a certain size.

Document Camera Terms - U

Document Camera UXGA Resolution
Document camera UXGA resolution is a 1600 pixel by 1200 pixel document camera resolution. UXGA is an abbreviation for Ultra eXtended Graphics Array. UXGA resolution is four times the resolution of SVGA (800 x 600).

Document Camera Terms - V

Document Camera Varifocal Lens
A varifocal document camera lens is a lens which contains three focal elements which are housed in a single assembly.
Vertical Resolution
Vertical resolution is the amount of horizontal lines that can be seen in the vertical direction of the display.
Document Camera VGA Resolution
Document camera VGA resolution is a 640 pixel by 480 pixel resolution which stands for Video Graphics Array.
Video Conferencing

Document cameras can be used with video conferencing equipment to effectively allow groups or individuals to communicate over long distances. As well as being able to hear the other party as with a conference call, video conferencing allows the two parties to see each other.

Video Compatibility
Video compatibility is how well a display device, such as a DLP or LCD projector or a computer monitor is able to receive data and play a variety of video standards, for example, SECAM, PAL and NTSC.
Document Camera Video In/Out
Video in/out uses a female BNC or RCA connector to transmit the signal from a document camera, VCR or DVD player to a display device such as a computer monitor or DLP or LCD projector.
Video Switchers
Video switchers are devices that are used when there are a number of video signals which need to connect to one or more display devices. For example, you may use a video switcher to switch the display on a monitor from a computer signal to a document camera signal and back.
A visualizer is another word used to describe a document camera or digital presenter. Occasionally document camera manufacturers use these different terms to differentiate their document cameras in the marketplace.
V sync is an abbreviation for vertical synchronization. Vertical synchronization marks the beginning of a frame in a video signal.

Document Camera Terms - W

Whiteboard (Interactive)
See Interactive Whiteboard.

Document Camera Terms - X

XGA Document Camera Resolution
XGA document camera resolution stands for Extended Graphics Array. An XGA document camera resolution is 1024 pixels by 768 pixels.

Document Camera Terms - Y

Y/C Document Camera Signal
Y/C is a type of document camera signal which is also called separate video, (abbreviated to s-video). Y/C connectors carry analog video signals from the document camera to the display device which are split into two separate signals, one for brightness and one for color. This is different to a composite video signals which carry both the color and brightness information in a single signal line. Y/C signals is the most commonly used document camera video signal and carries high bandwidth 480i or 576i resolution video (standard definition video). Y/C cables need separate cables to carry audio signals.
A Y cable is a type of cable which divides a monitor’s signal so that a signal from a document camera could be used simultaneously with both a monitor and another display device, for example a document camera confidence monitor.

Document Camera Terms - Z

Document Camera Zoom lens
A document camera’s zoom lens is a lens that has a variable focal length. This allows the user of the document camera to adjust the size of the image being projected on the projection screen by adjusting the zoom lens via the document camera’s control panel or its remote control device.