Glossary of Terms

The Security industry is a complex and often highly technical business. Our glass is the last word in the security terms.

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ActiveX is a standard that enables software components to interact with one another in a networked environment, regardless of the language(s) used to create them. Web browsers may come into contact with ActiveX controls, ActiveX documents, and ActiveX scripts. ActiveX controls are often downloaded and installed automatically as required.

AF (Autofocus)

A system by which the camera lens automatically focuses on a selected part of the subject.


The field of view, relative to a standard lens in a 35mm still camera, expressed in degrees, i.e. 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.

ARP (Address Resolution Protocol)

This protocol is used to associate an IP address to a hardware MAC (Media Access Control) address. A request is broadcast on the local network to discover the MAC address for an IP address.

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.

Auto Iris (AI)

This special type of iris is electrically controlled by the camera, to automatically regulate the amount of light allowed to pass through the lens to the image sensor of the camera.

Auto White Balance (AWB)

Auto White Balance is a color camera feature that uses a complex algorithm to set the proper balance of primary colors (red -green-blue) to reproduce accurate color images when displayed on a monitor.
The AWC circuit samples the image and tries to determine what is the neutral or gray or white area or areas of the image and then using that reference sets the RGB values accordingly. For the best results a white card is held in the camera’s view (at least 40% of scene) when AWB is selected. Many surveillance cameras do not cover static scenes therefore ATW circuits are used for constantly monitoring, re-evaluating and adjusting the color values. There are also manual color settings (R +B) that can be used if the scene that the camera is viewing has constant consistent lighting.
Many cameras have presets that reference values for lighting given in degrees of Kelvin. These reference values are typically referencing outdoor sunlight from 6200°≥10,000° and indoor lighting from 2000≥5500 depending on if the light is from tungsten(2000°-3500°) or fluorescent(4000°-5500°) bulbs.

Automatic Gain Control (AGC)

Automatic Gain Control is employed in CCTV cameras in an attempt to keep the output signal at or near the specified one volt peak to peak (written 1Vp-p). The video signal output is sampled and fed back into the video amplifier as a reference to maintain the recommended one volt output signal. The AGC circuit in most modern day CCTV cameras with auto-iris lenses only comes into play after the lens iris is fully open.  Some AGC circuits can amplify the video signal as much as 32 times but with every increase in amplification more video noise is introduced into the picture. Video noise is seen as graininess, blotchiness or distortion.  If a camera’s menu has AGC settings as an option choose the lowest amount of AGC gain to give a usable picture during the time of lowest light.

AVI (Audio Video Interleave)

A video format that supports simultaneous playback of audio and video