CCTV - Closed-circuit television
CCTV (closed-circuit television) is a TV system in which signals are not publicly distributed but are monitored, primarily for surveillance and security purposes.
CCTV relies on strategic placement of cameras, and observation of the camera's input on monitors somewhere. Because the cameras communicate with monitors and/or video recorders across private coaxial cable runs or wireless communication links, they gain the designation "closed-circuit" to indicate that access to their content is limited by design only to those able to see it.
Older CCTV systems used small, low-resolution black and white monitors with no interactive capabilities. Modern CCTV displays can be color, high-resolution displays and can include the ability to zoom in on an image or track something (or someone) among their features. Talk CCTV allows an overseer to speak to people within range of the camera's associated speakers.
CCTV is commonly used for a variety of purposes, including:
- Maintaining perimeter security in medium- to high-secure areas and installations.
- Observing the behavior of incarcerated inmates and potentially dangerous patients in medical facilities.
- Traffic monitoring.
- Overseeing locations that would be hazardous to a human, for example, highly radioactive or toxic industrial environments.
- Building and grounds security.
- Obtaining a visual record of activities in situations where it is necessary to maintain proper security or access controls (for example, in a diamond cutting or sorting operation; in banks, casinos, or airports).
CCTV is finding increasing use in law-enforcement, for everything from traffic observation (and automated ticketing) to an observation of high-crime areas or neighborhoods. Such use of CCTV technology has fueled privacy concerns in many parts of the world, particularly in those areas in the UK and Europe where it has become a routine part of police procedure.
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A 2009 systematic review by researchers from Northeastern University and University of Cambridge used meta-analytic techniques to pool the average effect of CCTV on crime across 41 different studies. The results indicated that
- CCTV caused a significant reduction of crime by on average 16%.
- The largest effects of CCTV were found in car parks, where cameras reduced crime by on average 51%.
- CCTV schemes in other public settings had small and non-statistically significant effects on crime: 7% reduction in city and town centers and 23% reduction in public transport settings.
- When sorted by country, systems in the United Kingdom accounted for the majority of the decrease; the drop in other areas was insignificant.
The studies included in the meta-analysis used quasi-experimental evaluation designs that involve before-and-after measures of crime in experimental and control areas. However, several researchers have pointed to methodological problems associated with this research literature. First, researchers have argued that the British car park studies included in the meta-analysis cannot accurately control for the fact that CCTV was introduced simultaneously with a range of other security-related measures. Second, some have noted that, in many of the studies, there may be issues with selection bias since the introduction of CCTV was potentially endogenous to previous crime trends. In particular, the estimated effects may be biased if CCTV is introduced in response to crime trends.
It has been argued that problems of selection bias and endogeneity can be addressed by stronger research designs such as randomized controlled trials and natural experiments. A 2017 review published in Journal of Scandinavian Studies in Criminology and Crime Prevention compiles seven studies that use such research designs. The studies included in the review found that CCTV reduced crime by 24-28% in public streets and urban subway stations. It also found that CCTV could decrease unruly behaviour in football stadiums and theft in supermarkets/mass merchant stores. However, there was no evidence of CCTV having desirable effects in parking facilities or suburban subway stations. Furthermore, the review indicates that CCTV is more effective in preventing property crimes than in violent crimes.
Another question in the effectiveness of CCTV for policing is around uptime of the system; in 2013 City of Philadelphia Auditor found that the $15M system was operational only 32% of the time. 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 fundamental 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 vehicles, often with automatic number plate recognition, and a network of APNI-linked cameras is used to manage London's congestion charging zone.
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 Spriggs did a Cost-effectiveness analysis (CEA) 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. Critics however noted that benefits of non-monetary value cannot be captured in a traditional Cost Effectiveness Analysis and were omitted from their study. 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.
Cities such as Manchester in the UK are using DVR-based technology to improve accessibility for crime prevention.
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. Civil liberties campaigners criticized the idea as "a distasteful and a worrying development".
In 2013 Oaxaca hired deaf police officers to lip read conversations to uncover criminal conspiracies.
In Singapore, since 2012, thousands of CCTV cameras have helped deter loan sharks, nab litterbugs and stop illegal parking, according to government figures.
In recent years, the use of body worn video cameras has been introduced for a number of uses. For example, as a new form of surveillance in law enforcement, with cameras located on a police officer's chest or head.
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.
Many cities and motorway networks have extensive traffic-monitoring systems, using closed-circuit television to detect congestion and notice accidents. Many of these cameras however, are owned by private companies and transmit data to drivers' GPS systems.
The UK Highways Agency has a publicly owned CCTV network of over 3000 Pan-Tilt-Zoom cameras covering the British motorway and trunk road network. These cameras are primarily used to monitor traffic conditions and are not used as speed cameras. With the addition of fixed cameras for the active traffic management system, the number of cameras on the Highways Agency's CCTV network is likely to increase significantly over the next few years.
The London congestion charge is enforced by cameras positioned at the boundaries of and inside the congestion charge zone, which automatically read the licence plates of cars. If the driver does not pay the charge then a fine will be imposed. Similar systems are being developed as a means of locating cars reported stolen.
Other surveillance cameras serve as traffic enforcement cameras.
A CCTV system may be installed where any example, on a Driver-only operated train CCTV cameras may allow the driver to confirm that people are clear of doors before closing them and starting the train.
Many sporting events in the United States use CCTV inside the venue for fans to see the action while they are away from their seats. The cameras send the feed to a central control center where a producer selects feeds to send to the television monitors that fans can view. CCTV monitors for viewing the event by attendees are often placed in lounges, hallways, and restrooms. This use of CCTV is not used for surveillance purposes.
Organizations use CCTV to monitor the actions of workers. Every action is recorded as an information block with subtitles that explain the performed operation. This helps to track the actions of workers, especially when they are making critical financial transactions, such as correcting or cancelling of a sale, withdrawing money or altering personal information.
Actions which an employer may wish to monitor could include:
- Scanning of goods, selection of goods, introduction of price and quantity;
- Input and output of operators in the system when entering passwords;
- Deleting operations and modifying existing documents;
- Implementation of certain operations, such as financial statements or operations with cash;
- Moving goods, revaluation scrapping and counting;
- Control in the kitchen of fast food restaurants;
- Change of settings, reports and other official functions.
Each of these operations is transmitted with a description, allowing detailed monitoring of all actions of the operator. Some systems allow the user to search for a specific event by time of occurrence and text description, and perform statistical evaluation of operator behaviour. This allows the software to predict deviations from the standard workflow and record only anomalous behaviour.
Use in schools
In the United States, Britain, Australia and New Zealand, CCTV is widely used in schools due to its success in preventing bullying, vandalism, monitoring visitors and maintaining a record of evidence in the event of a crime. There are some restrictions on installation, with cameras not being installed in an area where there is a "reasonable expectation of privacy", such as bathrooms, gym locker areas and private offices (unless consent by the office occupant is given). Сameras are generally acceptable in hallways, parking lots, front offices where students, employees, and parents come and go, gymnasiums, cafeterias, supply rooms and classrooms. The installation of cameras in classrooms may be objected to by some teachers.
Criminals may use surveillance cameras to monitor the public. For example, a hidden camera at an ATM can capture people's PINs as they are entered, without their knowledge. The devices are small enough not to be noticed, and are placed where they can monitor the keypad of the machine as people enter their PINs. Images may be transmitted wirelessly to the criminal. Even lawful surveillance cameras sometimes have their data go into the hands of people who have no legal right to receive it.
Computer-controlled analytics and identification
Computer-controlled cameras can 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, but rather object classification. 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, defocus and other so called camera tampering events.
VCA analytics can also be used to detect unusual patterns in an environment. The system can be set to detect anomalies in a crowd, for instance a person moving in the opposite direction in airports where passengers are supposed to walk only in one direction out of a plane or in a subway where people are not supposed to exit through the entrances.
VCA can 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.
A 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. Insta 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. Conservative critics fear the possibility that one would no longer have anonymity in public places. 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.
Comparatively harmless are people counter systems. They use CCTV equipment as front end eyes of devices which perform shape recognition technology in order to identify objects as human beings and count people passing pre-defined areas.
Retention, storage and preservation
Most CCTV systems may record and store digital video and images to a digital video recorder (DVR) or, in the case of IP cameras, directly to a server, either on-site or offsite.
There is a cost in the retention of the images produced by CCTV systems. The amount and quality of data stored on storage media is subject to compression ratios, images stored per second, image size and is effected by the retention period of the videos or images. DVRs store images in a variety of proprietary file formats. Recordings may be retained for a preset amount of time and then automatically archived, overwritten or deleted, the period being determined by the organisation that generated them.
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. Increasingly, 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.
A growing branch in CCTV is internet protocol cameras (IP cameras). It is estimated that 2014 was the first year that IP cameras outsold analog 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 phone, this is considered remote access. For professional or public infrastructure security applications, IP video is restricted to within a private network or VPN, or 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 homeowners 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.
New York City has a similar network called the Domain Awareness System.
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 Service, Transport 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 allow different security systems, like CCTV, access control, intruder alarms and intercoms to operate together. For example, when an intruder alarm is activated, CCTV cameras covering the intrusion area are recorded at a higher frame rate and transmitted to an Alarm Receiving Centre.
Wireless security cameras
Many consumers are turning to wireless security cameras for home surveillance. 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, but lack the reliability of hard-wired cameras. 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.
In Wiltshire, UK, 2003, a pilot scheme for what is now known as "Talking CCTV" was put into action; allowing operators of CCTV cameras to order offenders to stop what they were doing, ranging from ordering subjects to pick up their rubbish and put it in a bin to ordering groups of vandals to disperse. In 2005, Ray Mallon, the mayor and former senior police officer of Middlesbrough implemented "Talking CCTV" in his area.
Other towns have had such cameras installed. In 2007 several of the devices were installed in Bridlington town centre, East Riding of Yorkshire.