SST : Security-Systems Technology

Analytics
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
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

SB - 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.