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
All industries have their own
“buzz” words and specific language. The use of computer
vision to analyse security video draws from three different industries:
CCTV
Computer Networking
Machine Vision
Each of which brings some of its own jargon to the market. We
have tried to include a simple list of the most common terms you
are likely to find quoted in articles and sales presentations
as you evaluate vendors and systems in this area.
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802.11
A standard for wireless computer networking
Analytics - Wikipedia says
The use of computer algorithms to filter incoming CCTV video feeds;
to alert an operator to events.
Behaviour Recognition
A sophisticated method of Analytics where people and / or vehicles
are tracked between images to see if they are acting usually or
unusually.
Bit Depth - Wikipedia says
The number of digital shades that the brightness value for a given
pixel is converted into. Black is always given a value of zero,
in 8 bit processing white is 255 (256 shades) and in 10 bit processing
white is 1023 (1024 separate digital shades).
Blob Analysis
Unknown objects in an image are often called blobs, the analysis
of their shape, size motion etc in order to classify them is often
known as blob analysis.
CCD
Charge Coupled Device. A type of semiconductor chip designed to
accurately convert the incoming photons into an electrical signal.
Made up of a matrix of discrete sensing areas called pixels
Centriod
The (x,y) balance or centre of mass of an object, often the point
used in tracking
algorithms.
Checksum
A 16 bit calculated field used to ensure detection of corrupted
data transfer in TCP/IP communications.
Colour Space
A mathematical representation of colour controlled by a number
of colour components like RGB or HSB.
Compression Ratio
This is the ratio of uncompressed image data size to the compressed
image data size. The higher the ration, the greater the amount
of compression.
Content Analysis
Another name for Video Analytics
Concept Coding
Another name for Video Analytics
Digital Signal Processor
(DSP)
A semiconductor microprocessor specifically designed for processing
digital signals like digital images.
DHCP
Dynamic Host Configuration Protocol. A computer networking protocol
that provides dynamic assignment of IP addresses.
DNS
Domain name system – a system for naming resources on TCP/IP
networks
Dynamic range
The brightness range of an image’s digital scale also known
as Grey Scale
Encryption
This is the process of systematically altering data to make it
unreadable to unauthorised users.
Feature Extraction
Normally the second step in image analysis that seeks to measure
the individual features of the blobs or objects in the scene.
Firewall
This is a device that protects a network from unauthorised access.
Fuzzy logic
See Neural network
Fully Functional camera
A camera which is live to a Control Room and has Pan, Tilt and
Zoom functionality available.
FTP
File Transfer Protocol. This is a method of transferring data
between systems on a computer network with significant built in
error checking to prevent data loss or corruption. In addition
to transferring files it can create and delete directories and
display the content of directories.
Grey Scale
See Dynamic range
HSB - Hue,
Saturation and Brightness colour space
A mathematical colour representation based on how humans perceive
colour.
H.261
A standardised image compression scheme for motion image sequences,
based on transform coding techniques
I Frame
This is the Image frame in motion compression algorithms, like
MPEG4, used as the basis to compare the next n frames to; thereby
enabling only the transmission their changes from the I Frame
and thereby reducing the amount of data transmitted.
IP Address
A method of locating a physical resource like a computer or digital
camera on a TCP/IP computer network
Image Analysis
The processing of image data in a computer, to extract quantitative
measurements and classify the results.
Image Compression
The reduction of the data size in a digital image, by removing
forms of data redundancy from the raw image data.
Image segmentation
The first stage in image analysis, which seeks to simplify the
data into its basic component elements or objects within the scene.
Interframe Coding
The technique used in compression methods like MPEG4 which looks
for dis-similarities between the image frame and a previous reference
frame
Intelligent Video
See Analytics
JPEG
A standard image compression technique that works on single images.
Lossless compression
A form of image compression where the data content of the original
image is precisely preserved.
Lossy Compression
The original content is not preserved but the quality is set at
some arbitrary level.
MJPEG
A specialised form of JPEG for the compression of image sequences.
MPEG4
Image Compression algorithm based on I Frames. Similar to H.261
Neural Network
A method of object classification that is based on training the
software using actual image data.
Nyquist limit
50% of the sampling rate. A digitised image will contain no spatial
frequency content above the Nyquist limit. Therefore a camera
with 100 pixels in the x axis will not resolve anything smaller
than 2 pixels wide or 2% of the field of view.
Object
Any element of interest in the image, such as a person or vehicle.
Blobs are converted into objects during image analysis.
Object Classification
The third stage of image analysis where the feature measurements
of a blob are compared against a set of criteria to determine
if the blob belongs to a particular class of objects, for example
vehicles.
Object Tracking
A method of following an object through successive image frames
to determine how it is moving relative to other objects. This
is most commonly done by measuring the position of the centroid
of the object in (x, y) in successive frames.
PAL
Phase alternation line. The composite colour specification for
analogue CCTV cameras, primarily found in Europe with a frame
rate of 25 frames per second.
Pixel
The smallest discreet spatial component in a digital image. Also
a single photo-sensing element in a CCD sensor.
Progressive Scan
A form of camera acquisition timing where all the pixels in the
CCD are exposed at the same time. It removes the image blur caused
in PAL standard cameras due to fast moving objects.
Reference Frame
See I Frame
Router
A connectivity device that forwards data based on the IP address
Shape Measure
Any measurement that describes some aspect of an blob’s
shape characteristics such as area, height, perimeter distance
or a ratio between two or more such characteristics (height :
area). This is often used to help to determine Object Classification.
Smart Camera
A camera which has a built in Digital Signal Processor, to allow
the image processing to be performed within the camera and only
the result transmitted.
Smart CCTV Camera
A sub set of Smart Cameras specifically designed for security
applications where they will alert predefined people and systems
when a specific security breach is occurring. They require very
limited computer bandwidth except when their inbuilt image processor
believes that an event maybe taking place.
Subnet
A logical subdivision of the address space defined by a TCP/IP
network ID.
TCO
Total Cost of ownership – the cost of purchasing, operating,
maintaining and ultimately disposing of electronic systems
TCP/IP
A protocol system for computer communications across networks
and the internet. Two key features are end node verification,
the sending and receiving systems are responsible for acknowledging
and verifying the transmission; and dynamic routing, where the
data path is based to the present conditions and may pass through
multiple routes.
Tracking
The following of a blob or an object on a frame to frame basis
to see how it moves with respect to the rest of the scene.
UDP
A non reliable, but fast connectionless transport protocol for
moving data between systems in a TCP/IP environment. There is
limited error checking.
Voxel
A three dimensional version of a pixel. |
