Closed-circuit television (CCTV), also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point (P2P), point to multipoint (P2MP), or mesh wired or 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, stores, and other areas where security is needed. Though Videotelephony is seldom called ‘CCTV’ one exception is the use of video in distance education, where it is an important tool.
Surveillance of the public using CCTV is common in many areas around the world. In recent years, the use of body worn video cameras has been introduced as a new form of surveillance, often used in law enforcement, with cameras located on a police officer’s chest or head. Video surveillance has generated significant debate about balancing its use with individuals’ right to privacy even when in public.
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, utilizing digital 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 cameras, perhaps equipped with megapixel sensors, support recording directly to network-attached storage devices, or internal flash for completely stand-alone operation.
There are about 350 million surveillance cameras worldwide as of 2016. About 65% of these cameras are installed in Asia. The growth of CCTV has been slowing in recent years.
The earliest video surveillance systems involved constant monitoring because there was no way to record and store information. The development of reel-to-reel media enabled the recording of surveillance footage. These systems required magnetic tapes to be changed manually, which was a time consuming, expensive and unreliable process, with the operator having to manually thread the tape from the tape reel through the recorder onto an empty take-up reel. Due to these shortcomings, video surveillance was not widespread. VCR technology became available in the 1970s, making it easier to record and erase information, and use of video surveillance became more common.
During the 1990s, digital multiplexing was developed, allowing several cameras to record at once, as well as time lapse and motion-only recording. This increased savings of time and money which then led to an increase in the use of CCTV.
Recently CCTV technology has been enhanced with a shift toward Internet-based products and systems, and other technological developments.
Closed-circuit television was used as a form of pay-per-view theatre television for sports such as professional boxing and professional wrestling. Boxing telecasts were broadcast live to a select number of venues, mostly theaters, where viewers paid for tickets to watch the fight live. The first fight with a closed-circuit telecast was Joe Louis vs. Joe Walcott in 1948. Closed-circuit telecasts peaked in popularity with Muhammad Ali in the 1960s and 1970s, with “The Rumble in the Jungle” fight drawing 50 million CCTV viewers worldwide in 1974, and the “Thrilla in Manila” drawing 100 million CCTV viewers worldwide in 1975. In 1985, the WrestleMania professional wrestling show was seen by over one million viewers with this scheme. As late as 1996, the Julio César Chávez vs. Oscar De La Hoya boxing fight had 750,000 viewers. Closed-circuit television was gradually replaced by pay-per-view home cable television in the 1980s and 1990s.
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. Another early appearance was in 1973 in Times Square in New York City. 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. Nevertheless, during the 1980s video surveillance began to spread across the country specifically targeting public areas. It was seen as a cheaper way to deter crime compared to increasing the size of the police departments. Some businesses as well, especially those that were prone to theft, began to use video surveillance. 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. CCTV later became common in banks and stores to discourage theft, by recording evidence of criminal activity. In 1998, 3,000 CCTV systems were in use in New York City. A study by Nieto in 2008 found many businesses in the United States had invested heavily in video surveillance technology to protect products and promote safe workplace and consumer environments. A nationwide survey of a wide variety of companies found that 75 percent utilize CCTV surveillance. In private sector CCTV surveillance technology is operated in a wide variety of establishments such as in industry/manufacturing, retailing, financial/insurance/banking, transportation and distribution, utilities/communications, health care, and hotels/motels, parking areas, jewelry shops.
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. The first use by local government was in King’s Lynn, Norfolk, in 1987. 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 an increase in the number of CCTV systems installed. Today, systems cover most town and city centres, and many stations, car-parks and estates.
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.
CCTV systems are often used for security monitoring purposes in organizations and homes.
Video surveillance and terrorism
Material collected by surveillance cameras has been used as a tool in post-event forensics to identify tactics, techniques and perpetrators of terrorist attacks. Furthermore, there are various projects − such as INDECT − that aim to detect suspicious behaviours of individuals and crowds. It has been argued that terrorists won’t be deterred by cameras, that terror attacks aren’t really the subject of the current use of video surveillance and that terrorists might even see it as an extra channel for propaganda and publication of their acts. In Germany calls for extended video surveillance by the country’s main political parties, SPD, CDU and CSU have been dismissed as “little more than a placebo for a subjective feeling of security”.
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.