Aberration – Any inherent imperfections or deficiencies in a lens that leads to a loss in shape or sharpness of captured images or video.
ABF (Auto Back Focus) – Technology that allows the camera to adjust the position of the image sensor to obtain optimal focus. This feature can also be accessed via the Web Client.
Access Control (Physical) – Restrictive measures in the form of a device or system that restricts access to an area or facility to authorized personnel. Such measures include keypads, card readers, security turnstiles, and more.
Access Control System – A network of devices and hardware setup to help restrict access to entrances and exits of a specified area or building to designated parties.
AC Adaptor – An external power supply or transformer for electronic devices like wireless security cameras, gaming systems, laptops, and more. Also known as an AC converter, it converts the direct current (DC) from the wall outlet into an alternating current (AC) that the device will better handle.
ActiveX – A standard that enables software components to interact with one another in a networked environment, regardless of the language(s) used to create them. Comes in document, script, control, and other forms of the same name that the browser typically comes into contact with. The system typically downloads additional controls as needed.
AF (Autofocus) – A system by which the camera lens automatically focuses on a selected part of the subject.
AGC (Automatic Gain Control) – An electronic circuit that amplifies the video signal when the strength of the signal falls below a given value.
Alarm Input – An aspect of select security cameras, DVR recorders, and NVR recorders that accept signals from sensor devices. Such sensor devices include door or window sensors, motion detection lasers, and more that emit a signal upon being activated. This signal will set the home or business alarm off while also causing a security camera system to start recording.
ALC (Automatic Light Control) – A motion detection aspect of security systems that activate floodlights or connected devices that emits light upon activation by connected motion detectors or other devices.
Angle – The field of view, relative to a standard lens in a 35mm still camera, expressed in degrees, e.g. 30°. For practical purposes, this is the area that a lens can cover, where the angle of view is determined by the focal length of the lens. A wide-angle lens has a short focal length and covers a wider angle of view than standard or telephoto lenses, which have longer focal lengths.
Angle of View – May be expressed in Diagonal, Horizontal, or Vertical. Smaller focal lengths give a wider angle of view.
ANR (Automatic Network Recovery) – A function that can be found in or downloaded to NVRs (Network Video Recorders) that automatically store video data on IPC (Internet Protocol Camera) storage cards when the network is disconnected. After the recovery of the network, The NVR with this function automatically transfers the data stored through this method.
Aperture – The opening of the lens that controls the amount of light reaching the surface of the pickup device. The size of the aperture is controlled by the iris adjustment.
Aperture Scale – The aperture scale is referred to as an F-number. The international aperture scale is: F1, F1.4, F2, F2.8, F4, F4.6, F8, F11, F16, etc.
ARP (Address Resolution Protocol) – A protocol used to associate an IP address to a hardware MAC address. Upon being used, a request is broadcast on the local network to discover the MAC address for an IP address.
ARTPEC (Axis Real Time Picture Encoder) – A chip designed by Axis for image compression. It supports a range of CCD and CMOS sensors, built-in functionality for sharpening, backlight compensation, noise reduction and white balance, support for multiple Motion-JPEG streams, support for MPEG-4 part 2, up to 30 frames/second from 4 simultaneous video sources and real-time compression of up to 45 Megapixels/second.
ASIC (Application Specific Integrated Circuit) – A circuit designed for a specific application, as opposed to a general purpose circuit, such as a microprocessor.
Aspect ratio – A ratio of width to height in images. A common aspect ratio used for television screens and computer monitors is 4:3. High-definition television (HDTV) uses an aspect ratio of 9:16.
Aspherical Lens – A lens one or more of whose elements has a non-spherical surface. Aspherical surfaces are shaped to reduce the spherical and other aberrations.
Audio – Defined as one or several capabilities in a camera or electronic device. Such capabilities include producing noise, allowing for remote communications through the device, providing prerecorded messages, or scaring off intruders with loud alarms.
Auto Iris Lens – A function of security cameras that quickly adjusts the incoming light to allow for a superior image quality even during varying and shifting light conditions.
AVI (Audio Video Interleave) – A video format that supports simultaneous playback of audio and video.
B #
Back Focus – A term used to describe the relationship of the distance of the lens to the image device. This distance is critical to maintaining the proper depth of field through changing focal lengths and varying light conditions. The correct back focus is normally achieved by adjusting the image pick-up device on the camera itself.
Bandwidth – The given capacity a connection can transfer data in a given time. Often, the measurement used for this transfer of data is megabits per second or Mbps.
Bitmap – A data file representing a rectangular grid of pixels. It defines a display space and color for each pixel (or “bit”) in the display space. This type of image is known as a “raster graphic.” GIF’s and JPEG’s are examples of image file types that contain the data file.
Because a bitmap uses this fixed raster method, it cannot easily be rescaled without losing definition. Conversely, a vector graphic image uses geometrical shapes to represent the image, and can thus be quickly rescaled.
Bit rate – The measurement of bits per second transferred through a digital network.
BLC (Back Light Compensation) – A function of the camera that compensates for excessive light directed at the camera, which causes the video to bloom or the images in front of the light to be unusable.
Bluetooth – An open standard for wireless transmission of voice and data between mobile devices (PCs, handheld computers, telephones and printers).
Bonjour – Also known as zero-configuration networking, this Apple designed set of protocols provides for the network devices, applications, and services with a specific type of communication. Applicable with Windows and Apple devices in a network.
BOOTP (Bootstrap Protocol) – A protocol that can automatically configure a network device (give it an IP address). This protocol is the basis for a more advanced network management protocol, the Dynamic Host Configuration Protocol (DHCP).
Broadband – In network engineering terms, this describes transmission methods where two or more signals share the same carrier. In more popular terminology, the term is taken to mean high-speed data transmission.
C #
Camera Format – The approximate size of a camera image pickup device. This measurement is derived from the diagonal line of a chip or the diameter of the tube. Currently there are five format sizes in the CCTV industry: 1″, 2/3″, ?”, 1/3″ and, ?”
Cable – A catch-all term that can refer to sturdy metal ropes used in construction or insulated wiring crafted for a specific purpose like transmitting power or signals. For security systems, it is the wiring that circulates data and constantly powers each device.
C-Mount – An industry standard for mounting a lens to a camera where a 1? x 32 thread is employed and the distance from the image plane is 17.52mm from the shoulder of the lens. A C-mount lens may be used CS-mount camera with the use of a 5mm-adapter ring.
CCD (Charged Coupled Device) – This light-sensitive image device used in many digital cameras is a large integrated circuit that contains hundreds of thousands of photo-sites (pixels) that convert light energy into electronic signals. Its size is measured diagonally and can be 1/4″, 1/3″, 1/2″ or 2/3″.
CGI (Common Gateway Interface) – A specification for communication between a web server and other (CGI) programs. For example, an HTML page that contains a form might use a the program to process the form data once it is submitted.
CIF (Common Intermediate Format) – Refers to the analog video resolutions 352×288 pixels (PAL) and 352×240 pixels (NTSC). See also Resolution.
Client/server – Describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfils the request. Typically, multiple client programs share the services of a common server program. A web browser is a client program that requests services (the sending of web pages or files) from a web server.
CMOS (Complementary Metal Oxide Semiconductor) – A widely used type of semiconductor that uses both negative and positive circuits. Since only one of the circuit types is on at any given time, these devices require less power than chips using just one type of transistor. Image sensors in the same category also allow processing circuits to be included on the same chip, an advantage not possible with CCD sensors, which are also much more expensive to produce.
Coaxial cable – The standard means of transmitting analog video in a CCTV system that is also used by cable companies to distribute television in residential buildings.
Codec – In communications engineering, this is usually a coder/decoder. The device is used in integrated circuits or chips that convert e.g. analog video and audio signals into a digital format for transmission. They convert received digital signals back into analog format while also using analog-to-digital conversion and digital-to-analog conversion in the same chip.
Codec can also mean compression/decompression, in which case it is generally taken to mean an algorithm or computer program for reducing the size of large files and programs.
Composite video – A type of video signal in which the red, blue and green signals (sometimes audio signals too) are mixed together.
Compression – Encoding a video or image file to efficiently take up less data and be more easily shared.
Contrast – Defines the degree of difference between the lightest and darkest parts of an image or video stream.
Control unit – If a CCTV system has more than one camera, there must be a way to control the video signals going to recorders and monitors. There are three basic types of Video Control Unit: Multiplexer, Switch and Quad.
CS-Mount – A relatively new industry standard for mounting a lens to a camera where a 1″ X 32 thread is employed and the distance from the image plane from the shoulder of the lens is 12.52mm. A CS-mount lens may NOT be used on a C-mount camera.
D #
Day and Night Camera – A security camera that records quality video in full daylight and low light settings. This capability is done through an advanced CCD chip or sometimes an adjustable internal system that uses infrared technology that automatically covers during the day.
DC TYPE AUTO-IRIS – Auto-iris lenses where the iris is controlled by the circuitry of the camera.
DC-Iris – This special type of iris is electrically controlled by the camera, to automatically regulate the amount of light allowed to enter.
DCIF (Double Common Intermediate Format) – A format of color images whose resolution is 528 x 384 pixels (PAL) or 528 x 320 pixels (NTSC)
Decoder – Paired with an encoder, this device breaks down incoming data that comes from newer cameras and is encoded by the following encoder for older systems..
Deinterlacing – Changing videos made for analog (interlaced) to progressive or non-interlaced mediums. This is for higher quality modes of viewing video like video broadcasts, Blu-Ray, LCD computer monitors, and HDTV.
DOF (Depth of Field) – The regions in front of and behind the focused distance where the image remains in focus. When greater, more of the scene near to far is in focus. Lens aperture and scene lighting will greatly influence the D.O.F.
DHCP (Dynamic Host Configuration Protocol) – Is a protocol that lets network administrators automate and centrally manage the assignment of Internet Protocol (IP) addresses to network devices in a network.
The protocol uses the concept of a “lease” or amount of time that a given IP address will be valid for a computer. The lease time can vary, depending on how long a user is likely to require the network connection at a particular location. It also supports static addresses for e.g. computers running web servers, which need a permanent IP address.
Digital Watermark – This technology embeds the device information onto the recorded video. They may be used to verify the authenticity or integrity of the video or to show the identity of its owners.
DNS (Domain Name System) – Is used to locate and translate Internet domain names into IP (Internet Protocol) addresses. A domain name is a meaningful and easy-to-remember name for an Internet address. For example the domain name www.example.com is much easier to remember than 192.0.34.166. The translation tables for domain names are contained in Domain name servers.
Domain server – Domains can also be used by organizations that wish to centralize the management of their (Windows) computers. Each user within a domain has an account that usually allows them to log in to and use any computer in the domain, although restrictions may also apply. The domain server is the server that authenticates the users on the network.
Dual Stream – It means a channel of video images passing through the video coder, and output 2 independent bit streams. The resolution, frame rate, bit rate and other parameters of output bit stream can be set independently. The output dual steam can meet different demands, for example, one for hard disk storage and the other for network transmission.
Duplex – A point to point communication system made up of two or more connected systems or devices that feature two way communication.
Dynamic Adjustment of Encoding Parameters – The user adjusted encoding parameters can take effect at once without pausing or restarting of network transmitting and recording.
In the surveillance system, for static monitoring scene, video can be recorded in low bit rate through reducing resolution, image quality, bit rate and frame rate, while changing of image scene requires higher resolution , bit rate and frame rate of video, etc to get high quality video stream. Since the above parameters can be dynamically modified, continuous images can be maintained without switching files frequently. And it does not only meet the requirement of high-quality images at critical moments, but also save the disk space and network bandwidth.
E #
EIS (Electronic Image Stabilization) – Reduces the affects of vibrations or slight movements from environmental affects like wind, machinery, or other sources.
Extension Tubes – Various size spacers used between the camera and lens to reduce the Minimum Object Distance. Not recommended for use with zoom lenses due to the loss of tracking ability.
Encoder – A device used to adapt data captured by an analog camera into a signal that matches what newer IP camera systems use. Generally, this device is paired with a decoder to make older cameras work with modern camera systems.
Ethernet – The most widely installed local area network technology that typically uses special grades of twisted pair wires. The most commonly installed systems that include the technology are 10BASE-T and 100BASE-T10, which provide transmission speeds up to 10 Mbps and 100 Mbps respectively.
ETRAX (Ethernet Token Ring AXIS) – A chip that is the cornerstone of Axis technology and the ‘brain’ in nearly all Axis products. A multipurpose Linux chip with integrated Ethernet networking and extremely flexible I/O options.
F #
F-Number – Indicates the brightness of the image formed by the lens, controlled by the iris. The smaller this is, the brighter the image.
F-Stop – A term used to indicate the speed of a lens. The smaller the F-number the greater amount of light passes through the lens.
Factory default settings – These are the settings that originally applied for a device when it was first delivered from the factory. If it should become necessary to reset a device to its factory default settings, this will, for many devices, completely reset any settings that were changed by the user.
Field of View – The horizontal or vertical scene size at a given length from the camera to the subject.
Firewall – A cyber security barrier between networks, e.g. between a Local Area Network and the Internet. The barrier ensures that only authorized users are allowed to access the one network from the other while it can be software running on a computer or it can be a standalone hardware device.
Focal Length – The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite position. The focal length determines the size of the image and angle of FOV seen by the camera through the lens. This is the center of the lens to the image pickup device.
Fixed Iris – A function of security cameras that forces the system to remain consistent when receiving light when recording. This function is ideal in indoor environments like homes, schools, and offices.
FTP (File Transfer Protocol) – Is an application protocol that uses the TCP/IP protocols, used to exchange files between computers/devices on networks.
Frame – Is a complete video image. In the 2:1 interlaced scanning format of the
RS-170 and CCIR formats, this video image is made up of two separate fields of 262.5 or 312.5 lines interlaced at 60 or 50 Hz to form a complete one, which appears at 30 or 25 Hz. In video cameras with a progressive scan, each frame is scanned line-by-line and not interlaced; most are also displayed at 30 and 25 Hz.
Frame Rate – The number of consecutive frames that are recorded or shown in a video within a given amount of time. Modern entertainment and security cameras generally focus on achieving well over 24 frames in one second, measured explicitly as frames per second or FPS.
FPS – Frames per second.
Full-duplex – Transmission of data in two directions simultaneously. In an audio system this would describe e.g. a telephone system. Half-duplex also provides bi-directional communication, but only in one direction at a time, as in a walkie-talkie system. See also Simplex.
G #
Gain – When concerning voltage, the increase in ratio from output to input. This is measured in decibels or dB.
H #
HD-TVI (High Definition Transport Video Interface) – Is an open standard for analog video transmission and is based on the original analog transmission media. Advantages in such a standard include:
- Farther transmission distance
- Higher video resolution
- Reliable anti-interference performance as it carries low-frequency signal
HDCVI – High Definition Composite Video Interface
HDD (Hard disk drive) – is the mechanism that controls the positioning, reading and writing of the hard disk, which furnishes data storage.
HLC (High Light Compensation) – A function that handles conditions with a strong light source towards the camera, there will be over-exposed areas, or “high light.” The function automatically recognizes and constrains the high light to make objects more distinguishable.
Hunting – An industry term used to describe a auto-iris lenses inability to stabilize under certain light conditions.
I #
Infrared – Light that is low frequency and used by devices like security cameras with night vision to allow recording in low light or complete darkness.
IRIS – A mechanical diaphragm which can be controlled manually or automatically to adjust the lens aperture.
L #
Lens Format – The approximate size of a lens projected image. In most cases the lens will project a image slightly greater than the designated image size to insure the pickup device is completely covered. It is recommended that camera and lenses are the same format size. A lens of a larger format size can be used on a smaller format camera, however a smaller format lens should never be used with a larger format camera.
Lens Speed – Refers to the lens aperture or its ability to transmit light. This is measured in F-stops.
Level Control – Used to set the auto-iris circuit to a video level desired by the user. Turning the level potentiometer towards the HIGH position will open the iris allowing more light to pass through the lens, towards the LOW will close the iris allowing less light to pass through the lens.
M #
Manual Iris Lens – A lens with a manual adjustment to set the iris opening (aperture) to a fixed position. This type lens is generally used in fixed lighting conditions.
Megapixel – A unit of measurement in digital imaging equal to one million pixels.
MOD (Minimum Object Detection) – The closest distance a given lens will be able to focus upon a object. Generally the smaller the focal length the shorter the closest distance. This distance can be altered with use of extension tubes.
Motion Detection – If there is any motion in the configured detection area, the camera will automatically detect the event and can trigger preconfigured alarms or recording. Users can set sensitivity level, detection area, and arming schedule accordingly.
Multi-Address Mode – Is an NVR (Network Video Recorder) function on networks with more than one NIC (Network Interface Controller). Each NIC works independently with separate parameter settings, which can be assigned with a different IP address in a different network. The function can be used to establish network isolation.
N #
Night Vision Camera – Specific security cameras that use infrared technology to provide a clear view into low light or completely dark environments. Unlike night and day cameras, these surveillance cameras can see in total darkness with the specific distance dependent on the particular camera.
Noise Reduction – A feature in modern security cameras for home and business use that improves the quality of recorded data by mitigating the visible effects brought by noise. Especially effective for low light videos and also known as DNR on commercial security cameras, this feature incorporates frame-by-frame analysis known as 2D or scans multiple frames at once in a given time known as 3D. Either can be accompanied by spatial noise reduction, which smooths out areas of high-frequency noise.
O #
Outdoor Camera – Specific classification of security cameras made more sturdy through features that may include a weatherproof exterior, cold weather resistance, infrared, anti-glare lens, and a tamper-proof design. Additionally, such parts of security systems require more durable security camera mounts for enhanced viability.
P #
Pinhole Lens – Lenses used primarily in covert applications where the camera/lens must remain out of sight.
Pixel – The smallest controllable unit of measurement in digital imaging while also improving resolution when more in number.
Power Supply – Devices that connect to a home or business electrical supply through standard electrical outlets and filter a specified current to instruments like security cameras and other electronic systems. Examples of such devices include AC adapters, which detail the specific amount of electricity that will pass through them.
Pre-Position Lenses – Specially designed lenses with extra mechanical/electrical components to allow for computer interfacing. The extra components allows the lens (when used with the appropriate controller) to feedback to the controller information relevant to zoom and focus propositioning allowing the controller to quickly scan to a pre-selected scene, arriving in focus at the proper zoom point without operator intervention.
R #
RAID (Redundant Array of Independent Disks) – A storage technology that combines multiple disk drive components into a logical unit. The setup stores data over multiple hard disk drives to provide enough redundancy so that data can be recovered if one disk fails. Data is distributed across the drives in one of several ways called “RAID levels,” depending on what level of redundancy and performance is required.
Resolution – The specific reference to the number of pixels in a given frame on a monitor, television screen, or any other electronic display.
S #
SD Card Support – The capability of any electronic device to receive an SD card and use it as internal storage.
Shutter – The specific function of regular and security cameras that filters the required amount of light necessary into the sensor to allow for viewable imagery.
Shutter Speed – The speed at which the shutter can operate when adjusting to the needs of a sensor in a regular, surveillance, or security camera.
Smart IR – Provides cameras the capability to edit the level of infrared light projected by the device to fit the specific distance for viewing.
S/N Ratio – Specifically meaning signal to noise ratio, which is used to precisely compare the preferred signal to the exact background noise. With security cameras, the ratio refers to what a camera can take in terms of signal noise and still deliver a satisfactory result.
Spot Filter – A neutral density filter paced at the center of one of the elements (or on an iris blade) to increase the high end of the F-stop range of the lens.
T #
Telephoto – A term used to describe lenses that have a high focal number causing the reproduced image to appear larger than human eye reproduction.
Tracking – A zoom lenses ability to remain in focus throughout the entire zoom range.
Transformer – Devices made to increase or decrease voltage from a power source to instruments like video surveillance products and other electronics. Examples of such devices include AC adaptors, phone chargers, and more.
V #
VARI-FOCAL – A low cost version of a zoom lens designed to meet installers needs for versatility. This lens does not have the ability to track from wide to telephoto.
VCA (Video Content Analysis) – is the capability to analyze video automatically to detect and determine temporal and spatial events. Many smart functionalities can be implemented with the capability such as intrusion detection, line crossing detection, etc.
VIDEO TYPE LENS – An auto-iris lens with internal circuitry for processing of the video signal which controls the iris movements.
VQD (Video Quality Diagnosis) – Is a feature that monitors the video for abnormal qualities (i.e., blurred image, abnormal brightness, and color cast). An alarm will be triggered and linked with configured response actions.
W #
Weatherproof – A description applied to the exterior of a product like outdoor cameras, sometimes the product entirely, that signifies it can be reliable outside. This description should, however, be seen as a quality only for regular weather patterns. It may not be as effective in extreme cold, coastal environments, water submersion, or to tampering.
WDR (Wide Dynamic Range) – In conditions with very bright and dark areas, such as at an entrance door in an office building or an entranceway to an indoor parking garage or tunnel, a camera may capture over-exposed images in bright areas and under-exposed images in dark areas, which greatly affects image quality. A camera with the capability can help solve this issue. By combining images with short exposure (for bright areas) and long exposure (for dark areas) into one image, the technology captures both bright areas and dark areas clearly.
Wireless Camera – Cameras defined by the lack of wiring used for installation and the use of Wi-Fi, radio, Bluetooth, or another signal to transfer data. While these devices use much less wiring during install, they generally require power through AC adaptors or ethernet cables.
Z #
Zoom Lens – A lens with the ability to change its focal length manually or through the use of a controller to cover a variety of needs.
Zoom Ratio – The ratio of the starting focal length (wide) to the ending focal length (telephoto) of a zoom lens. A 10X zoom will magnify the image at the wide end by 10 times. Examples of a 10X zoom lenses; 8mm~80mm, 12mm~120mm.
# #
2D DNR (Digital Noise Reduction) – Also known as 2D Digital Noise Reduction, this feature is common in the modern security camera. Applied to captured videos, it is an improvement that analyses each frame and removes the grainy effect caused by noise.
3D DNR (Digital Noise Reduction) – Also known as 3D Digital Noise Reduction, this improvement is a standard feature for modern security cameras for home and business use. The feature scans multiple frames of a video in a given time and removes the physical effects of noise which tend to be granular.
