Industry Terms, Jargon - Glossary
_ | 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
AUTO or MANUAL IRIS : Generally we tend to use auto iris lenses externally where there are variations in the lighting levels. Manual iris lenses are used normally for internal applications where the light level remains constant. However, with the introduction of electronic iris cameras it is now possible to use manual iris lenses in varying light conditions and the camera should electronically compensate. There are several considerations to this option though: the setting of the F stop becomes critical; if the iris is opened fully to allow the camera to work at night, the depth of field will be very small and it may be more difficult to achieve sharp focus even during the day. The camera can maintain normal video levels, but it cannot affect the depth of field. If the iris is closed to increase the depth of field, the low light performance of the camera will be reduced.
B
Box Camera :
  • When mounting to a wall or any vertical area
  • When viewing long distances where a long lens is required, which would not fit inside a dome or bullet camera
  • When extreme low light conditions are not a consideration
NOTE: If the box camera is within someone’s reach the camera is usually inserted in a protective enclosure. If the lighting is extremely low box cameras can be inserted inside enclosures that have built-in infra-red illuminators but the camera must be infra-red sensitive. Meaning it is able to utilize the infra-red illuminators from an external source.
Browser : Short for Web browser , a software application used to locate and display Web pages. The two most popular browser s are Netscape Navigator and Microsoft Internet Explorer. Both of these are graphical browser s, which means that they can display graphics as well as text.
C
Caching : One problem in providing accurate results is the caching performed by your PC and ISP. Caching reduces the number of pages requested at the host server, as popular pages are stored locally either as temporary files on your hard drive or in the ISP's page cache. Since log files only record files requested from the server, the number registered in the log file can be incorrectly low.
CIF (Common Intermediate Format) : is used to standardize the horizontal and vertical resolutions in pixels of YCbCr sequences in video signals. A CIF is commonly defined as one-quarter of the 'full' resolution of the video system it is intended for (listed below as 4CIF). Note that this full resolution does not match what is currently referred to as D1 video (based upon Sony's D1 format).
Video resolutions (in pixels) x NTSC-based x PAL-based
CIF (NTSC 352 × 240) - (PAL 352 × 288)
4CIF (NTSC 704 × 480) - (PAL 704 × 576)
D1 (NTSC 720 × 480) - (PAL 720 × 576)
NTSC is the video system or standard used in North America and most of South America. In NTSC, 30 frames are transmitted each second. Each frame is made up of 525 individual scan lines.
PAL is the predominant video system or standard mostly used overseas. In PAL, 25 frames are transmitted each second. Each frame is made up of 625 individual scan lines.
D
DEPTH OF FIELD : The depth of field refers to the area within the field of view which is in focus. A large depth of field means that a large percentage of the field of view is in focus, from objects close to the lens often to infinity. A shallow depth of field has only a small section of the field of view in focus. The depth of field is influenced by several factors. A wide angle lens generally has a larger depth of field than a telephoto lens, and a higher F stop setting typically has a larger depth of field than a lower setting. With auto iris lenses, the automatic adjustment of the aperture also means constant variation of depth of field. The small depth of field is most apparent at night when the lens is fully open and the depth of field is at its minimum. Objects that were in focus during the day may become out of focus at night.
DivX Compression : DivX is a software application that uses the MPEG-4 standard to compress digital video, so it can be downloaded over a DSL/cable modem connection in a relatively short time with no reduced visual quality. The latest version of the codec, DivX 4.0, is being developed jointly by DivXNetworks and the open source community. DivX works on Windows 98, ME, 2000, CE, Mac and Linux.
E
Extranet : refers to an Intranet that is accessible externally with authorization.
F
Firewall or proxy server : The incoming web traffic that passes through a firewall or proxy server to reach the web server is in most cases identified by a single IP address of the firewall or proxy server. This is called Address Translation. The log file will in a case like this only contain one unique IP Address even if multiple users from behind the same firewall or proxy server visited the web site. Analyzers will these visits as visits from the same user.
Focal length : The focal length of the lens is measured in mm and directly relates to the angle of view that will be achieved. Short focal lengths provide wide angles of view and long focal lengths become telephoto, with narrow angles of view. A "normal" angle of view is similar to what we see with our own eye, and has a relative focal length equal to the pick up device. Our online lens calculator is a simple to use device for estimating focal length, object dimension, and angles of view.
FTP : (File Transfer Protocol) the protocol for exchanging files over the Internet. FTP software is generally needed to communicate with a web server to send/recieve files. Some browser s include built-in support to handle FTP.
H
H.263 : Based on H.261 with enhancements that improve video quality over modems. It supportsCIF, QCIF, SQCIF, 4CIF and 16CIF resolutions.
H.264 : H.264, also known as MPEG-4 AVC (Advanced Video Coding), is a video compression standard that offers significantly greater compression than its predecessors. The standard offers up to twice the compression of the current MPEG-4 ASP (Advanced Simple Profile), in addition to improvements in perceptual quality. The H.264 standard can provide DVD-quality video at under 1 Mbps, and is optional for full-motion video over wireless, satellite, and ADSL Internet connections.
I
Infra-red Cameras :
  • When there are extreme low light conditions
  • When the camera is not within someone’s reach
NOTE: The distances infra-red cameras can see are based upon its illumination capacity. Infra-red cameras have LED’s, which cast out into the darkness. Realistically, a good rule of thumb (but not an absolute) is figure 1 foot for each LED. Therefore, if a camera has 30 LED’s then it probably can see about 30 feet. There are some newer LED’s called Cat’s Eyes, which have more power, but they are not very common. You would notice a Cat’s Eye by the extra large size of the LED’s. With respect to infrared quality it has more to do with the intensity of the LED's and the distance they cover. One thing to note is that infrared LED's do have a limited life since they are illuminating so they do burn out over time. Just because one camera has more LED's than another does not mean it can cast a longer distance, there are different strengths in the LED's. Unfortunately, again for the consumer it is hard to properly compare.
Intranet : a local internet application accessible only to an organization's members or employees, or others with authorization. Intranets are generally used to facilitate business processes or share information and data between an organization.
ISO/IEC : International Organization for Standardization - a non-governmental organization that works to promote the development of standardization to facilitate the international exchange of goods and services and spur worldwide intellectual, scientific, technological and economic activity.
International Electrotechnical Commission - international standards and assessment body for the fields of electrotechnology

Codec - A video codec is software that can compress a video source (encoding) as well as play compressed video (decompress).
CIF - Common Intermediate Format - a set of standard video formats used in videoconferencing, defined by their resolution. The original CIF is also known as Full CIF (FCIF).
QCIF - Quarter CIF (resolution 176x144)
SQCIF - Sub quarter CIF (resolution 128x96)
4CIF - 4 x CIF (resolution 704x576)
16CIF - 16 x CIF (resolution 1408x1152

ISP : (Internet Service Provider) a company that provides accessto the Internet. For a monthly fee, the service provider gives you a software package, username, password and access phone number. Equipped with a modem, you can then log on to the Internet and browse the World Wide Web and USENET, and send and receive e-mail.
J
JPEG : Stands for Joint Photographic Experts Group. It is also an ISO/IEC working group, but works to build standards for continuous tone image coding. JPEG is a lossy compression technique used for full-color or gray-scale images, by exploiting the fact that the human eye will not notice small color changes.
JPEG : Stands for Joint Photographic Experts Group. It is also an ISO/IEC working group, but works to build standards for continuous tone image coding. JPEG is a lossy compression technique used for full-color or gray-scale images, by exploiting the fact that the human eye will not notice small color changes.
L
M
MPEG : Stands for the Moving Picture Experts Group MPEG is an ISO/IEC working group, established in 1988 to develop standards for digital audio and video formats. There are five MPEG standards being used or in development. Each compression standard was designed with a specific application and bit rate in mind, although MPEG compression scales well with increased bit rates.
P
Pan Tilt Zoom (PTZ) Cameras :
  • When you want live control of the camera and adjusting the manual pan, tilt or zoom on a fixed cameras is not practical
  • When you want to set up a camera to tour the premises
  • When you want to view several angles from a single camera
NOTE: Pan, Tilt, Zoom cameras cost anywhere from 5x – 10x the cost of a fixed camera. The Pan, Tilt, Zoom camera cannot record or see where it is not looking. You cannot pan, tilt or zoom after it has been recorded (this can only be done with a 360 degree camera). Making a PTZ camera wireless adds thousands to the cost. PTZ cameras can though perform various functions not possible with a fixed camera. You can control a PTZ camera and zoom in optically up to 36x and beyond digitally up to 12x giving zoom capabilities in the 100’s. The PTZ’s have intelligence and can be programmed to perform pre-defined tours and upon the event of an alarm the camera can swing to a specified location before continuing its tour. An operator can override and take control of the camera at any time.
S
V
Video Compression :
At its most basic level, compression is performed when an input video stream is analyzed and information that is indiscernible to the viewer is discarded. Each event is then assigned a code - commonly occurring events are assigned few bits and rare events will have codes more bits. These steps are commonly called signal analysis, quantization and variable length encoding respectively. There are four methods for compression, discrete cosine transform (DCT), vector quantization (VQ), fractal compression, and discrete wavelet transform (DWT).

Discrete cosine transform is a lossy compression algorithm that samples an image at regular intervals, analyzes the frequency components present in the sample, and discards those frequencies which do not affect the image as the human eye perceives it. DCT is the basis of standards such as JPEG, MPEG, H.261, and H.263.

Vector quantization is a lossy compression that looks at an array of data, instead of individualvalues. It can then generalize what it sees, compressing redundant data, while at the same time retaining the desired object or data stream's original intent.

Fractal compression is a form of VQ and is also a lossy compression. Compression is performed by locating self-similar sections of an image, then using a fractal algorithm to generate the sections.

Like DCT, discrete wavelet transform mathematically transforms an image into frequency components. The process is performed on the entire image, which differs from the other methods (DCT), that work on smaller pieces of the desired data. The result is a hierarchical representation of an image, where each layer represents a frequency band.

VIDEO DRIVE or DIRECT DRIVE : With auto iris lenses it is necessary to control the operation of the iris to maintain perfect picture levels. Video driven lenses contain amplifier circuitry to convert the video signal from the camera into iris motor control. With direct drive lenses, the camera must contain the amplifier circuitry, and the lens now only contains the galvanometric iris motor making it less expensive. The deciding factor depends on the auto iris output of the camera. Most now have both types.
W