Closed-Circuit Television (CCTV)
Description: http://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Three_Surveillance_cameras.jpg/220px-Three_Surveillance_cameras.jpg Surveillance cameras on a corner.
Description: http://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Dome_CCTV_cameras.JPG/220px-Dome_CCTV_cameras.JPG

Dome CCTV cameras
Closed-circuit television (CCTV) is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs frombroadcast television in that the signal is not openly transmitted, though it may employ point to point (P2P), point to multipoint, or mesh wireless links. Though almost all video cameras fit this definition, the term is most often applied to those used for surveillance in areas that may need monitoring such as banks, casinos, airports, military installations, and convenience stores. Videotelephony is seldom called "CCTV" but the use of video in distance education, where it is an important tool, is often so called.
In industrial plants, CCTV equipment may be used to observe parts of a process from a central control room, for example when the environment is not suitable for humans. CCTV systems may operate continuously or only as required to monitor a particular event. A more advanced form of CCTV, utilizingDigital Video Recorders (DVRs), provides recording for possibly many years, with a variety of quality and performance options and extra features (such as motion-detection and email alerts). More recently, decentralized IP-based CCTV cameras, some equipped with megapixel sensors, support recording directly to network-attached storage devices, or internal flash for completely stand-alone operation. Surveillance of the public using CCTV is particularly common in many areas around the world including the United Kingdom, where there are reportedly more cameras per person than in any other country in the world.[3] There and elsewhere, its increasing use has triggered a debate about security versus privacy.
The first CCTV system was installed by Siemens AG at Test Stand VII in Peenemünde, Germany in 1942, for observing the launch of V-2 rockets.[4] The noted German engineer Walter Bruch was responsible for the design and installation of the system.
In the U.S. the first commercial closed-circuit television system became available in 1949, called Vericon. Very little is known about Vericon except it was advertised as not requiring a government permit.[5]
CCTV recording systems are still often used at modern launch sites to record the flight of the rockets, in order to find the possible causes of malfunctions,[6][7] while larger rockets are often fitted with CCTV allowing pictures of stage separation to be transmitted back to earth by radio link.[8]
The history of CCTV in the United States varies from that of the United Kingdom. One of its first appearances was in 1973 in Times Square in New York City.[9] The NYPD installed it in order to deter crime that was occurring in the area however crime rates did not appear to drop much due to the cameras.[9] Nevertheless, during the 1980s video surveillance began to spread across the country specifically targeting public areas.[10] It was seen as a cheaper way to deter crime compared to increasing the size of the police departments.[9] Some businesses as well, especially those that were prone to theft, began to use video surveillance.[9]
During the 1990s digital multiplexing, which allowed for several cameras at once to record, and introduced time lapse and motion only recording, increased the use of CCTV across the country[10] and increased the savings of time an money. From the mid 1990s on, police departments across the country installed an increasing number of cameras in various public spaces including housing projects, schools and public parks departments.[9]Following the September 11 attacks, the use of video surveillance has become a common occurrence in the country to deter future terrorist attacks.[9]
In September 1968, Olean, New York was the first city in the United States to install video cameras along its main business street in an effort to fight crime.[11]
CCTV later became very common in banks and stores to discourage theft, by recording evidence of criminal activity. Their use further popularised the concept. The first place to use CCTV in the United Kingdom was King's Lynn, Norfolk.[12]
In recent decades, especially with general crime fears growing in the 1990s and 2000s, public space use of surveillance cameras has taken off, especially in some countries such as the United Kingdom.

Crime prevention

Experiments in the UK during the 1970s and 1980s (including outdoor CCTV in Bournemouth in 1985), led to several larger trial programs later that decade.[12]
These were deemed successful in the government report "CCTV: Looking Out For You", issued by the Home Office in 1994, and paved the way for a massive increase in the number of CCTV systems installed. Today, systems cover most town and city centres, and many stations, car-parks and estates.
A more recent analysis by Northeastern University and the University of Cambridge, "Public Area CCTV and Crime Prevention: An Updated Systematic Review and Meta-Analysis," examined 44 different studies that collectively surveyed areas from the United Kingdom to U.S. cities such as Cincinnati and New York.
The analysis found that:

  1. Surveillance systems were most effective in parking lots, where their use resulted in a 51% decrease in crime;
  2. Public transportation areas saw a 23% decrease in crimes;
  3. Systems in public settings were the least effective, with just a 7% decrease in crimes overall. When sorted by country, however, systems in the United Kingdom accounted for the majority of the decrease; the drop in other areas was insignificant.[13]

The results from the above 2009 “Public Area CCTV and Crime Prevention: An Updated Systematic Review and Meta-Analysis” conducted by Walsh and Farrington,[13][14] are somewhat controversial.[15] Earlier similar meta-analysis completed by Welsh and Farrington in 2002 showed similar results: a significant decrease in car park crime (41%), and a non-significant decrease of crime in public transit and public places.[16] This study was criticized for the inclusion of confounding variables (e.g. notification of CCTV cameras on site, improved street lighting) found in the studies analyzed (including car park studies). These factors could not be teased apart from the effect of CCTV cameras being present or absent while crimes were being committed.[14][15] Thus, a combination of factors might be important for the decrease in crime not just the CCTV cameras. The 2009 study admitted to similar problems as well as issues with the consistency of the percentage of area covered by CCTV cameras within the tested sites (e.g. car parks have more cameras per square inch than public transit).[14] There is still much research to be done to determine the effectiveness of CCTV cameras on crime prevention before any conclusions can be drawn.
There is strong anecdotal evidence that CCTV aids in detection and conviction of offenders; indeed UK police forces routinely seek CCTV recordings after crimes. Moreover CCTV has played a crucial role in tracing the movements of suspects or victims and is widely regarded by antiterrorist officers as a fudamental tool in tracking terrorist suspects. Large-scale CCTV installations have played a key part of the defences against terrorism since the 1970s. Cameras have also been installed on public transport in the hope of deterring crime, and in mobile police surveillance vans, often with automatic number plate recognition, and a network of APNI-linked cameras is used to manage London's congestion charging zone. Even so there is political hostility to surveillance and several commentators downplay the evidence of CCTV's effectiveness, especially in the US.However, most of these assertions are based on poor methodology or imperfect comparisons. A more open question is whether most CCTV is cost-effective. While low-quality domestic kits are cheap the professional installation and maintenance of high definition CCTV is expensive Gill and Spring did a cost-benefit analysis of CCTV in crime prevention that showed little monetary saving with the installation of CCTV as most of the crimes prevented resulted in little monetary loss. It was however noted that benefits of non-monetary value cannot be captured in a traditional cost-benefit analysis and were omitted from their study. To get a full understanding of the costs and benefits of CCTV in crime prevention these factors would have to be included. A 2008 Report by UK Police Chiefs concluded that only 3% of crimes were solved by CCTV. In London, a Metropolitan Police report showed that in 2008 only one crime was solved per 1000 cameras. In some cases CCTV cameras have become a target of attacks themselves
On July 22, 2005, Jean Charles de Menezes was shot dead by police at Stockwell tube station. According to brother Giovani Menezes, "The film showed that Jean did not have suspicious behaviour"
Because of the bombing attempts the previous day, some of the tapes had been supposedly removed from CCTV cameras for study, and they were not functional. An ongoing change to DVR-based technology may in future stop similar problems occurring.
In October 2009, an "Internet Eyes" website was announced which would pay members of the public to view CCTV camera images from their homes and report any crimes they witnessed. The site aimed to add "more eyes" to cameras which might be insufficiently monitored, but civil liberties campaigners criticized the idea as "a distasteful and a worrying development


Prevalence
The number of CCTV cameras in the UK is not known for certain because there is no requirement to register CCTV cameras. However, an article published in CCTV Image magazine estimates that the number of cameras in the UK is 1.85 million. The number is based on extrapolating from a comprehensive survey of public and private cameras within the Cheshire Constabulary jurisdiction.This works out as an average of one camera for every 32 people in the UK, although the density of cameras varies from place to place to such a degree as to make this figure almost meaningless. The Cheshire report also claims that the average person on a typical day would be seen by 70 CCTV cameras, although many of these sightings would be brief glimpses from cameras in shops.
The Cheshire figure is regarded as more dependable than a previous study by Michael McCahill and Clive Norris of UrbanEye published in 2002. Based on a small sample in Putney High Street, McCahill and Norris estimated the number of surveillance cameras in private premises in London at around 500,000 and the total number of cameras in the UK at around 4,200,000. According to their estimate the UK has one camera for every 14 people. Although it has been acknowledged for several years that the methodology behind this figure is somewhat dubious, it has continued to be quoted in the absence of a better figure.
The CCTV User Group estimates that there are around 1.5 million CCTV cameras in city centres, stations, airports, major retail areas and so forth. This figure does not include the smaller surveillance systems such as those that may be found in local corner shops and is therefore broadly in line with the Cheshire report.
Research conducted by the Scottish Centre for Crime and Justice Research and based on a survey of all Scottish local authorities, identified that there are over 2,200 public space CCTV cameras in Scotland


Hacking and video art
Hackers and guerrilla artists have exposed the vulnerabilities of the video systems in an act dubbed "video sniffing.They have crossed feeds, uploaded their own video feeds and used the video footage for artistic purposes.


Industrial processes
Industrial processes that take place under conditions dangerous for humans are today often supervised by CCTV. These are mainly processes in the chemical industry, the interior of reactors or facilities for manufacture of nuclear fuel. Special cameras for some of these purposes include line-scan cameras and thermographic cameras which allow operators to measure the temperature of the processes. The usage of CCTV in such processes is sometimes required by law

Technological developments

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Surveillance camera at London (Heathrow) Airport with a wiper for clear images during rain

Computer controlled analytics and identification
Today’s High-definition CCTV cameras have many computer controlled technologies that allow them to identify, track, and categorize objects in their field of view.
Video Content Analysis (VCA) is the capability of automatically analyzing video to detect and determine temporal events not based on a single image. As such, it can be seen as the automated equivalent of the biological visual cortex.
A system using VCA can recognize changes in the environment and even identify and compare objects in the database using size, speed, and sometimes colour. The camera’s actions can be programmed based on what it is “seeing”. For example; an alarm can be issued if an object has moved in a certain area, or if a painting is missing from a wall, or if a smoke or fire is detected, or if running people are detected, or if fallen people are detected and if someone has spray painted the lens, as well as video loss, lens cover, defocuss and other so called camera tampering events.
VCA analytics can also be used to detect unusual patterns in a videos environment. The system can be set to detect anomalies in a crowd of people, for instance a person moving in the opposite direction in airports where passengers are only supposed to walk in one direction out of a plane or in a subway where people are not supposed to exit through the entrances
VCA also has the ability to track people on a map by calculating their position from the images. It is then possible to link many cameras and track a person through an entire building or area. This can allow a person to be followed without having to analyze many hours of film. Currently the cameras have difficulty identifying individuals from video alone, but if connected to a key-card system, identities can be established and displayed as a tag over their heads on the video.
There is also a significant difference in where the VCA technology is placed, either the data is being processed within the cameras (on the edge) or by a centralized server. Both technologies have their pros and cons.[49]
Facial recognition system Is a computer application for automatically identifying or verifying a person from a digital image or a video frame from a video source. One of the ways to do this is by comparing selected facial features from the image and a facial database.
The combination of CCTV and facial recognition has been tried as a form of mass surveillance, but has been ineffective because of the low discriminating power of facial recognition technology and the very high number of false positives generated. This type of system has been proposed to compare faces at airports and seaports with those of suspected terrorists or other undesirable entrants.
Computerized monitoring of CCTV images is under development, so that a human CCTV operator does not have to endlessly look at all the screens, allowing an operator to observe many more CCTV cameras.[ These systems do not observe people directly. Instead, they track their behavior by looking for particular types of body-movement behavior, or particular types of clothing or baggage.
To many, the development of CCTV in public areas, linked to computer databases of people's pictures and identity, presents a serious breach of civil liberties. Critics fear the possibility that one would not be able to meet anonymously in a public place or drive and walk anonymously around a city. Demonstrations or assemblies in public places could be affected as the state would be able to collate lists of those leading them, taking part, or even just talking with protesters in the street.


Retention, storage and preservation
Most CCTV systems record and store digital video and images to a Digital Video Recorder or in the case of IP cameras directly to a server, either on-site or offsite.
The amount of data stored and the retention period of the video or pictures are subject to compression ratios, images stored per second, image size and duration of image retention before being overwritten. [51]
Recordings are usually kept for a preset amount of time and then automatically archived, overwritten or deleted. The amount of time the videos are kept allow retrieval and review in the event a crime was committed or the information needs to be studied for any number of reasons.


Closed-circuit digital photography (CCDP)
Closed-circuit digital photography (CCDP) is more suited for capturing and saving recorded high-resolution photographs, whereas closed-circuit television (CCTV) is more suitable for live-monitoring purposes.
However, an important feature of some CCTV systems is the ability to take high resolution images of the camera scene, e.g. on a time lapse or motion-detection basis. Images taken with a digital still camera often have higher resolution than those taken with some video cameras. Increasaingly, low-cost high-resolution digital still cameras can also be used for CCTV purposes.
Images may be monitored remotely when the computer is connected to a network.

IP cameras
A growing branch in CCTV is internet protocol cameras (IP cameras). IP cameras use the Internet Protocol (IP) used by most Local Area Networks(LANs) to transmit video across data networks in digital form. IP can optionally be transmitted across the public internet, allowing users to view their cameras through any internet connection available through a computer or a 3G phone. For professional or public infrastructure security applications, IP video is restricted to within a private network or VPNor can be recorded onto a remote server.


Networking CCTV cameras
The city of Chicago operates a networked video surveillance system which combines CCTV video feeds of government agencies with those of the private sector, installed in city buses, businesses, public schools, subway stations, housing projects etc. Even home owners are able to contribute footage. It is estimated to incorporate the video feeds of a total of 15,000 cameras.
The system is used by Chicago's Office of Emergency Management in case of an emergency call: it detects the caller's location and instantly displays the real-time video feed of the nearest security camera to the operator, not requiring any user intervention. While the system is far too vast to allow complete real-time monitoring, it stores the video data for later usage in order to provide possible evidence in criminal cases
London also has a network of CCTV systems that allows multiple authorities to view and control CCTV cameras in real time. The system allows authorities including the Metropolitan Police ServiceTransport for London and a number of London boroughs to share CCTV images between them. It uses a network protocol called Television Network Protocol to allow access to many more cameras than each individual system owner could afford to run and maintain.
The Glynn County Police Department uses a wireless mesh-networked system of portable battery-powered tripods for live megapixel video surveillance and central monitoring of tactical police situations. The systems can be used either on a stand-alone basis with secure communications to nearby police laptops, or within a larger mesh system with multiple tripods feeding video back to the command vehicle via wireless, and to police headquarters via 3G.

Integrated systems
Integrated systems allow users to connect remotely from the internet and view what their cameras are viewing remotely, similar to that of IP cameras. In one incident, a lady from Boynton Beach, Florida was able to watch her house get robbed and contacted police directly from her office at work.[54]

Wireless security cameras

Description: http://upload.wikimedia.org/wikipedia/en/thumb/e/ef/Lorex_digital_wireless_camera.jpg/220px-Lorex_digital_wireless_camera.jpg
Many consumers are turning to wireless security cameras for home surveillance also. Wireless cameras do not require a video cable for video/audio transmission, simply a cable for power. Wireless cameras are also easy and inexpensive to install. Previous generations of wireless security cameras relied on analog technology; modern wireless cameras use digital technology which delivers crisper audio, sharper video, and a secure and interference-free signal.