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Key Document Camera Technology Features

Document cameras or digital presenters rely on a variety of innovative technology features in order to make them a useful tool for adding interactivity and excitement to presentations, as well as making document cameras easy for presenters to use. Document Camera Experts USA has put together this document camera technology information section to give you a better idea of what each of these document camera technology features is and what each one does make document cameras so useful in the classroom, boardroom, courtroom or laboratory.

1-CCD Document Cameras

A document camera’s CCD stands for a Charge Coupled Device. Every document camera CCD consists of hundreds of thousands of pixels on a very minute chip, arranged in a grid alignment. Each pixel on the CCD chip responds to light that it is exposed to by storing a small electrical charge. The pixels respond to brightness but not color, and in a 1-CCD document camera a color image (at about half the resolution of the CCD) is produced by splitting the CCD’s pixels into the three primary colors. Green uses half of the pixels, while red and blue use a quarter of the pixels each. A color image is then produced by the document camera as it calculates the missing pixels.

How a 1-CCD camera renders an image How a 3-CCD camera renders an image

3-CCD Document Cameras

A 3-CCD document camera chip functions slightly differently to a 1-CCD document camera chip. In a 3-CCD document camera, three separate charge coupled devices are used for each of the primary colors of light: Red, Green and Blue. The document camera’s electronics then merge one pixel from each CCD to make a color pixel. This results in an image that is rendered in full color resolution, as opposed to the half resolution in a 1-CCD document camera. This means that the 3-CCD document camera’s images look more true to life than those of the 1-CCD digital presenter.

How a 3-CCD camera renders an image

Displaying 35mm Slide Film on a Document Camera

Since a document camera is able to display transparent images, these types of digital presenters are able to show 33mm slide film, although this medium is now rarely used by presenters. Document cameras are more likely to be used to display opaque documents, transparent acetate slides or three dimensional objects.

BNC Document Camera Connectors

BNC stands for Bayonet Neill Concelman, and is an RF connector and a type of connector that is used to terminate coaxial cable. BNC connectors are very popular in the audio visual industry because it is a good quality method of terminating coaxial cable.

Document Camera CCDs

The CCD in a document camera stands for a Charge Coupled Device. A document camera’s Charge Coupled Device is an electrical component that is made up of a large number of pixels contained on a chip, and it is used for storing information and creating images. The pixels, or sensors, on a document camera’s CCD convert light from the document camera’s lens into an electrical signal output, which is then used by the document camera to produce an image. Since document camera CCDs only respond to brightness and not color, additional imaging technology is required in order for the document camera to display a colored image.

Composite Video Document Camera Signal

Video signal from a document camera may be transmitted in composite video, usually when the display device being used to show the document camera’s images is an analog device. Composite video signal is a video signal where the information for luminance (brightness) and the information for chrominance (color), as well as synchronization information for the document camera’s images are transmitted as a single signal. The composite video connectors are normally yellow, and are frequently paired with red and white audio connectors. Composite video is usually in standard format, for example NTSC, PAL and SEECAM.

Complementary Metal Oxide Semiconductor (CMOS) Document Cameras

The complementary metal oxide semiconductor (CMOS) in a document camera would be used in the document camera’s image sensor as an alternative to a 1-CCD or 3-CCD chip. CMOS is a class of integrated circuits which along with document camera image sensors might be found in static RAM, microcontroller microprocessors and other digital logic circuits.

Contrast measurement Auto Focus

A document camera or visualizer’s contrast measurement auto focus is a feature which helps a document camera display an image with the best contrast possible. Contrast auto focus is a feature that is frequently found in cameras and video cameras which do not have shutters. Contrast inside a sensor field is measured via the document camera’s lens. The difference in intensity between pixels next to each other on the sensor is increased as the image is focused correctly, which means that the document camera’s optical system can be adjusted until the maximum contrast is detected.

Document Camera Depth of Field

A document camera’s depth of field is the distance in front of the document camera’s subject matter, and beyond it, that the document camera’s camera can bring into focus. The document camera’s depth of field is therefore an especially important feature when considering viewing three dimensional objects with the document camera, so that details in the foreground and background can both be focused properly.

Displaying Document Camera Images on DLP Projectors or TVs

Video and images captured by a document camera’s image sensor could be displayed on a DLP television or DLP projector. DLP is an abbreviation for Digital Light Processing which is an image reproduction technology that was originally developed in 1987 by the company Texas Instruments. To create an image from a document camera on a DLP projector, the projector uses a large number of very tiny mirrors which are contained on a semiconductor chip. Each tiny mirror represents one pixel of the document camera’s image, and the actual number of mirrors depends on the specific resolution of the display device, such as 1920 pixels by 1080 pixels (HDTV resolution) or 800 pixels by 600 pixels (SVGA resolution). Together, the mirrors and chip are known as a Digital Micromirror Device (DMD).

DVI Document Camera Connection

The Digital Visual Interface (DVI) is a video interface which could be used to give more sharpness to the visual quality of document camera images and video streams displayed on a wide variety of digital displays, for example digital LCD and DLP projectors and flat panel LCD TVs or monitors. The main purpose of DVI when used with a document camera would be to transport uncompressed digital video data from the document camera to the display device.

HDMI Document Camera Connection

The video signal from a document camera can be transmitted with an HDMI cable if an HDMI connection is available. HDMI stands for High Definition Multimedia Interface. An HDMI connection will usually display the best possible document camera picture as it is a completely digital video interface which is able to transmit streams of data that are uncompressed. HDMI is also a very versatile type of connection for a document camera, since it supports any computer or television video format, whether these be standard definition or high definition. HDMI cables also support 8 channels of digital audio.

Displaying Document Camera Images in HDTV

If the images and video from a document camera or digital presenter are shown in high definition television (HDTV), they will likely look very sharp, crisp and high quality, since HDTV is a digital TV broadcasting system which has a far higher resolution than traditional TV broadcast formats such as PAL, NTSC or SECAM which are used in varying parts of the world.

Document Camera Image Sensors

A document camera’s image sensor is a type of imaging device which functions to turn a visual image captured by a document camera’s lens into an electric signal which can then be processed by the document camera’s electronics. In a document camera specifically, the technology used in the image sensor would most likely either be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

Infrared Document Camera Remote Control

A document camera’s infrared remote control could be used to control the document camera’s functions remotely from a short distance away. The document camera’s remote control will usually take the form of a small, hand held wireless device which may be able to control the document camera’s zoom lens, auto focus feature or image capture functions, and will usually communicate with the document camera via an infrared or radio connection. Document camera remote controls are useful for presenters who might need to be mobile and venture away from the document camera during the presentation, or if the document camera is mounted on the ceiling.

Displaying Document Camera Images on LCD Projectors or TVs

A document camera, digital presenter or visualizer may frequently be connected to a LCD television or monitor, or an LCD projector which would be used to display the images and video from the document camera to an audience. LCD stands for liquid crystal display, and LCD displays are often flat, thin display devices made up of a number of crystals sandwiched between two electrode layers, and each crystal acts as a pixel in the display of the document camera’s images.

LED Document Camera Illumination

The illumination for the subject matter of document camera or visualizer is usually provided from either a light box, or with LED lighting structures. LED stands for a light emitting diode, which is an electroluminescent semiconductor device. LEDs are typically used for document camera illumination because they are efficient, and they are able to last a long time

Document Camera Lenses

The document camera’s lens is the device in the camera which focuses light from the document camera’s input on to the document camera’s image sensors. The document camera’s lens will usually be made from a piece of either shaped glass or plastic.

Measuring Document Camera Display Devices in Lumens

An LCD or DLP projector that could be used to display a document camera’s video or images will be often be rated for its "brightness" in terms of the number of lumens (symbol lm) that it is able to produce. The lumen is actually more accurately known as the International System of Units denomination of luminous flux which is a measure of the perceived power of light. Luminous flux is actually adjusted to compensate for the changing reactions of the human eye to varying light wavelengths.

Defining Pixels

An image from a document camera shown on a display device will be made up of a number of pixels, which is a term that is a combination of the words "picture" and "element". One pixel of a document camera’s image is a tiny graphical element, which when combined with thousands of other pixels makes up the document camera or digital presenter’s images. The resolution of the display device being used to show the visualizer’s image will be the determining factor in how visible the pixels are. In higher resolution devices, there are enough pixels available to create the image to render the pixels smooth and indistinct from each other. Lower resolutions may result in the document camera’s image experiencing pixilation, where jagged outlines of pixel corners can be clearly seen.

Defining Progressive Scan

A document camera’s images could be displayed on a display device such as a television utilizing progressive scan, also called non interlaced scanning. Progressive scan is used in LCD, plasma and DLP technology televisions, and is defined as any technique for transmitting, storing or displaying moving images, such as video from a document camera, in which the lines of each frame are drawn right after one another. Progressive scan is different to interlaced scan, used in traditional CRT TV systems, where first the odd lines of the image signal, then the even lines are drawn on the screen.

RCA or Phono Document Camera Connectors

RCA connectors (which stands for Radio Corporation of America, the company which first came up with the design in the 1940s) which may be found on cables connecting to or from a document camera or digital presenter, are also referred to as CINCH/AV connectors, RCA jacks, or phono connectors. The RCA connector is a type of connector that is commonly used by manufacturers of audio visual equipment such as document cameras and is often used as a connector for composite document camera video signals – colored yellow for composite video and red and white for associated audio.

RJ-45 Networked Document Cameras

Many new models of digital presenters and document cameras are supplied with an RJ-45 jack, which is an Ethernet jack for connection to the internet via a network cable. This feature enables the document camera to be connected up to a computer network, and it also means that the document camera’s firmware can be easily updated

Using a Document Camera as a Scanner

A computer scanner is a piece of imaging equipment which analyzes a two dimensional or three dimensional object and takes a digital image of it, which is then stored on the computer or the scanner itself. A digital presenter or document camera could actually be described as a type of scanner since a document camera can take well focused snap shots of these types of objects (for example printed text, photographs or handwriting) and then store them on the document camera itself or on a computer if one is connected.

Document Camera SD Cards

Document cameras often have storage space for images captured by the document camera, although this space is often limited. Many document cameras have the option to increase the size of the memory available for storing images using an SD card, or Secure Digital card. SD cards are a non-volatile flash memory card format which was developed by Toshiba, Matsushita and SanDisk to be used in portable devices which now includes document cameras, cellphones, GPS units and portable computers. Different sizes of SD card can be purchased to increase the document camera’s memory capacity.

Document Camera Signal

S-Video stands for Super Video, and is also called component video or Y/C video. If a video signal from a document camera is transmitted as an S-Video signal, this means that the information for luminance (brightness) and the information for chrominance (color) for the document camera’s images are transmitted separately. This gives much more picture clarity to the document camera image displayed on the display device over a traditional composite video signal where the luminance, chrominance and synchronization data are transmitted as a single signal.

SVGA Document Camera Resolution

SVGA stands for Super Video Graphics Array, and was originally developed as an extension to IBM’s VGA resolution standard. The term SVGA is usually used to describe a resolution of 800 pixels by 600 pixels. However, unlike other resolution standards which describe a specific resolution, the term Super VGA (defined by the Video Electronics Standards Association - VESA) is actually used to describe a wide range of computer display standards which a document camera’s image might be displayed using.

SXGA Document Camera Resolution

The standard computer monitor resolution SXGA, which stands for Super Extended Graphics Array, means that if an image from a document camera was displayed on an SXGA resolution device it would use a maximum of 1280 pixels horizontally by 1024 pixels vertically – a total pixel number of 1,310,720. Displaying a document cameras’ image on an SXGA device as opposed to an XGA device (the resolution which SXGA superseded) would produce a sharper image, since XGA only uses 1024 pixels horizontally by 768 pixels vertically.

Document Cameras and Telemedicine

Telemedicine is a term that is usually used in reference to using communications technology and information technology for the delivery of clinical care. This could mean that hospital might use a document camera to broadcast an operation or procedure across a computer network using videoconferencing, allowing people in geographically separate areas to interact with the images from the document camera.

Controlling a Document Camera Using Touch Screen Technology

Touch screens are a technology developed to allow users to interact with a display that is able to show and receive information on the same screen. Whereas a keyboard and mouse are the traditional ways to control a device, for example using a document camera via a PC connection, a touch screen overlay could replace these devices as the primary input method used to control the document camera. This could potentially make the system more user friendly.


TWAIN is an interesting document camera related term which is not actually an acronym for a document camera technology feature. In fact, the word TWAIN was originally used to describe the difficulties experienced when trying to interface image scanners with computers. It has also been said to stand for "Technology (or Toolkit or Thing) Without An (or Any) Intelligent (or Important or Interesting) Name". Despite not having a proper name, TWAIN is an important feature which could be used to allow a document camera to be controlled by a computer program, allowing the computer program to use the document camera’s output to acquiring images.

USB Document Camera Connection

USB, which stands for Universal Serial Bus, is a type of connection which was originally developed for computers as a universal method of connecting peripheral components such as keyboards or mice. The aim of this was to remove the complications with device drivers for computer parallel ports and serial ports. Since then the USB connection has become extremely common on a variety of devices, such as document cameras, video game systems and mp3 players. USB is often the connection that would be used to connect a document camera to a computer or laptop.

Video Conferencing with a Document Camera

A document camera can be an extremely useful digital device to share images of printed documents or 3D objects during a videoconference, also known as a videoteleconference. Videoconferencing with a document camera allows two or more individuals or groups in multiple locations to interact with live video, audio and the feed from the document camera simultaneously. This makes visual collaboration between groups in different geographical locations much easier.

VGA Document Camera Resolution

The abbreviation VGA, which stands for Video Graphics Array, is frequently used to refer to the analog computer display resolution which could display images from a document camera in 640 pixels horizontally by 480 pixels vertically. The VGA computer display standard was originally marketed by IBM in 1987. While a document camera’s image could be reproduced on a display device with a VGA resolution, it is unlikely that this would be the case since the VGA standard has been obsolete in display devices for a number of years, except in the pocket PC market which is beginning to adopt the VGA resolution as its new standard. In fact, if the term VGA is being applied to document camera technology, it is more likely that it is referring to the 15 pin D subminiature VGA connector which could be used to carry the video signal of many resolutions from a document camera to a display device.

The 640 pixel by 480 pixel VGA resolution was superseded officially by the XGA standard developed by IBM, but in actual fact there were a number of supersessions by other computer manufacturers, whose extensions to the VGA standard became known as Super VGA.   

WSXGA+ Document Camera Resolution

If a document camera’s images are reproduced on a display device with WSXGA+ resolution (which stands for Widescreen Super eXtended Graphics Array resolution), it is most likely that the device is a computer, since this 1680 pixel by 1050 pixel 16:10 aspect ratio resolution is a computer display standard. WSXGA+ is actually the widescreen version of SXGA+, however WSXGA+ is not approved by any organization.

XGA Document Camera Resolution

If the image from a document camera is displayed on a device with an XGA (eXtended Graphics Array) resolution, the document camera image will be reproduced on the device in a maximum of 1024 pixels horizontally by 768 pixels vertically. The XGA resolution standard was introduced in 1990 by IBM.