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P3344
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Axis P3344 [63/68] Glossary of terms

Glossary of Terms

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. web

browsers may come into contact with ActiveX controls, ActiveX

documents, and ActiveX scripts. ActiveX controls are often

downloaded and installed automatically as required.

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.

ARP (Address Resolution Protocol) - This protocol is used to

associate an IP address to a hardware MAC address. A request

is broadcast on the local network to discover the MAC address

for an IP address.

ARTPEC (Axis Real Time Picture Encoder) - This chip is used

for image compression, and image processing such as

conversion of raw image sensor data, color correction,

sharpening, noise filtering etc.

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.

Autoiris (DC-Iris) - This special type of iris is electrically

controlled by the camera, to automatically regulate the amount

of light allowed to enter.

Bitmap - A bitmap is 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.’ GIFs and JPEGs are examples of image file types

that contain bitmaps.

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 bit rate (in kbit/s or Mbit/s) is often referred to

as speed, but actually defines the number of bits/time unit and

not distance/time unit.

Bonjour - Also known as zero-configuration networking,

Bonjour enables devices to automatically discover each other

on a network, without having to enter IP addresses or configure

DNS servers. Bonjour is a trademark of Apple Computer, Inc.

Broadband - In network engineering terms, this describes

transmission methods where two or more signals share the

same carrier. In more popular terminology, broadband is taken

to mean high-speed data transmission.

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, a HTML page that contains a form

might use a CGI program to process the form data once it is

submitted.

CIF (Common Intermediate Format) - CIF refers to the analog

video resolutions 352x288 pixels (PAL) and 352x240 pixels

(NTSC). See also Resolution.

Client/Server - 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

CMOS is 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, CMOS chips require less power

than chips using just one type of transistor. CMOS image

sensors 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.

Codec - In communications engineering, a codec is usually a

coder/decoder. Codecs are used in integrated circuits or chips

that convert e.g. analog video signals into a digital format for

transmission. The codec also converts received digital signals

back into analog format. A codec uses 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.

Compression - See Image compression.

DC-Iris (Autoiris) - This special type of iris is electrically

controlled by the camera, to automatically regulate the amount

of light allowed to enter.

DHCP (Dynamic Host Configuration Protocol) - DHCP is a

protocol that lets network administrators automate and

centrally manage the assignment of Internet Protocol (IP)

addresses to network devices in a network.

DHCP 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.

DHCP also supports static addresses for e.g. computers running

web servers, which need a permanent IP address.

DNS (Domain Name System) - DNS 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

Axis P3344 [63/68] Glossary of terms

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