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AXIS P3301/AXIS P3304 - 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.
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 16:9.
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 and audio 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
