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CCTV video footage is a great source of evidence for courts and law enforcement agencies all
around the world. With the fundamental shift from analogue to digital surveillance systems, the amount
of CCTV video footage that is used in courtrooms in the form of the evidence has rapidly increased.
A CCTV system is expensive to implement, manage and maintain. If it is installed incorrectly or
maintenance procedures are not put into place, the entire CCTV solution can be very ineffective in
providing enough information about a security incident that may occur on your premises.
The evidential value of CCTV footage directly depends on its visual quality, integrity and the
authenticity of the original video files. The evidential value of CCTV footage also depends on the
procedures used for the gathering and handling of the image material retrieved from the CCTV system.
Bad equipment selection, mistakes in system setup and irregular maintenance can reduce the overall
performance of many CCTV systems. As a result, at the time of a crime being committed, a CCTV
system may not be able to capture the video with best possible quality. Later on, law enforcement officials
cannot retrieve valuable information from the footage that could help them identify any suspects, restore
the chain of events or quickly resolve the crime.
Very often, the suspect denies his involvement in the crime and the collected CCTV footage cannot
provide enough details that represent any distinctive features of the suspect (facial features, tattoos,
clothing, type of vehicle, license number plate, etc.).
Insufficient training of the staff can also lead to mistakes in the handling and retrieval of CCTV
footage, resulting in damaged video material, a reduction in its original quality or the integrity of the
video material being compromised.
The purpose of this document is to specify the major aspects that may affect the visual quality of
CCTV footage and its performance in effectively recording video.
1. Operational Guidance

Main purposes of surveillance:
Safety/security – CCTV provides an aid to the security and safety of your establishment.
Deterrence – a CCTV system can deter potential criminals and it can be used for crime
Crime investigation – the content of the image material can be examined by law enforcement
Reduction in insurance costs – a CCTV system installation can be requested by an insurance
There are some issues that should be taken into account before purchasing a CCTV surveillance
There are no post-production techniques that can significantly improve the initial quality of
CCTV footage that has been captured. The initial quality must be in accordance with the aim of
Often, it is not possible to cover all the security aspects (wide-angle and close-up images) with
one surveillance camera or several cameras of the same range. Good coverage of the premises using
different types of cameras with different lenses can offer multiple chances to record a suspect on camera.
There are no proper industry standards concerning the resolution, recorded media format, frame
rate, data and file formats. Most CCTV system manufacturers don’t even adhere to an AVI standard, or an
agreed to specification for the DVR hardware and software, file formats, compression and encoding.
There are now thousands of poorly documented or undocumented DVR systems. There are plenty of
unbranded low-cost DVR systems on the market now that cannot provide any customer support and may
contain faulty hardware or firmware. Check online for some customer reviews before purchasing
unknown or unbranded DVR systems.
The effective use of a CCTV system is not possible without properly planned operational
management, detailed documentation and sufficient training of the personnel using it, especially
regarding system control and the retrieval and extraction of the recorded video files.
The legal laws and operational and security procedures that protect the integrity of digital
evidence and its authenticity should be followed at all times.
1.1. Observational Purposes
Before the purchase and installation of a system, it is crucial to specify the purpose of the
observation (what should be seen, when and where?). Will the camera be viewing a wide area fairly close
to the camera? Will images from a narrow area or far away be important? What are the lighting
conditions, and will they change?
There are several security purposes that a CCTV system may serve:
a) Monitoring your territory and detecting the movement of people or vehicles:
It may be suitable for covering a wide area such as a car park to watch the flow of traffic, or the
movement of people where you do not need to pick out individual figures or detect the presence of a
person in the image without needing to see their face.
The figure of a person or a car moving in the area should occupy 5 – 10% of the screen height. The
observer has to be able to see the figures of people in variable weather and lighting conditions. Cameras
used for the purposes of monitoring and detecting movement can be used in wide areas where you do
not expect to capture any reasonable detail of the moving subjects or their actions.
Figure 1. person occupies 5-10% of the screen height
Outdoor cameras usually serve for the purposes of monitoring and detecting. For this reason, the
selection of an appropriate camera that can work in variable weather and lighting conditions with
protection against damage or vandalism is crucial. It will be well worth the time involved in choosing an
appropriate lens for your Monitor/Detect cameras in order to achieve the sustainable visual quality of
your video recordings. (see technical guidance for varifocal and auto-iris lenses).
b) Observing the events happening in your territory:
This is useful in areas where it is necessary to monitor a group of individuals such as outside
nightclubs and pubs, streets in a town centre, aisles and stock rooms in shops, car parking and other
places where the reasonable detail of the subject (person or car) is needed with some context to their
activity by monitoring the area around them.
If a still camera is used for this purpose, the figure of a person or a car moving in the area should
occupy 25 – 40% of the screen height:
Figure 2. A person occupies 25 – 40% of the screen
For outdoor cameras, the observer has to be able to see some characteristic details of the individual
or vehicle (such as clothing, type or model of the vehicle and probably some other distinctive details). For
indoor cameras, the lighting and camera focus should be adequate to capture clear images both day and
If you are using security staff for monitoring purposes, Pan-Tilt-Zoom (PTZ) cameras that are
capable of remote directional and zoom control can be used as an option.
c) Recognising people or vehicles involved in some event:
You should be able to say with a high degree of certainty whether or not an individual shown is the
same as someone seen before, recognise somebody you know, or determine that somebody is not known
to you.
If a still camera is used for person recognition purposes, the figure of a person should occupy at
least 50% of the screen height. The characteristic features of the person (clothing, posture, objects being
carried) or a vehicle (make, model, colour) have to be seen.
CCTV frames with such a level of detail usually allow law enforcement officials to capture the
major distinctive features of the suspect and identify him, or determine if the person seen on the footage
was involved in other crimes in the area.
One of the distinctive features of a person is his or her height. If there is a risk of masked robbery, it
is essential to be able to measure the height of the suspect using frames from your CCTV.
The measurement of a suspect’s height is essential, in that the entire figure of the suspect from their
feet to the top of their head can be seen at some point of the suspect’s movement with part of the floor
they are standing on.
d) Identifying people involved in some event:
In this case, it is necessary to be able to identify an individual in such a way that it can be
established beyond a reasonable doubt, and to record high quality facial images that can be used in a court
to prove someone’s identity beyond a reasonable doubt.
The figure of the person should occupy at least 100% of the screen height. The subject’s face must
fill at least 15% of the total image (frame):
Figure 3. A person occupies more than 100% of the screen, face fills 15% of the screen
If you need to be able to identify someone from your CCTV image, a higher resolution, better
dynamic range and faster lens should be chosen for the camera. The minimum recommended resolution is
640 x 480 pixels. But remember, some cheap types of hardware (for example, web cameras) with this
amount of resolution are not suitable for facial recognition no matter what.
Camera height is very important, so make sure it is close to eye level. It helps to be able to see
facial features at a good angle or identify a suspect wearing a peaked cap.
Suitable and sufficient lighting will also have an influence on the visibility of facial features. If you
have bright light coming in from a window, you may need to add some light from the opposite direction
of the natural light in order to even things out, or install a window shade.
1.2. Location and Activity to monitor, Site plan
Good coverage of your premises offers multiple chances to capture a suspect on camera. Ideally,
you need to have all four types of cameras (Monitor, Observe, Recognize, Identify) to satisfy all the
requirements of the surveillance purposes mentioned above. You should determine your own risks in
order to select and operate an appropriate system that meets your objectives.
If any security incident happens on your premises, wide-angle monitor/detect cameras will provide
you with an overall impression about the chain of events – which direction the suspects came from, where
they were heading after the security incident occurred, how long they were within your territory and what
they did before entering it.
Images from your outdoor monitor/detect cameras could be used by law enforcement officials in
other crime investigations that have happened in your neighbourhood. So, it is very important to set up
your outdoor monitor/detect cameras for good detailed images, while considering the variable weather
and lighting conditions and checking if the people and objects are in focus. The mounting heights for each
camera must also support the camera’s purposes so that they can provide the required view. The mounting
of wide-angle monitor/detect purpose outdoor cameras higher than 8m above the ground is not
recommended. Outdoor cameras should be mounted at a suitable height that makes them difficult to
access by thieves or vandals. Additional protection can be provided for a CCTV system by adding or
embedding cameras within the site’s security alarm system, along with the use of durable camera
housings and anti-climbing devices.
As previously mentioned, neighbourhood security can be kept in mind as one of the purposes for
your CCTV system. But of course, the main issue is to address your own crime and security risks. The
best way to assess this is to determine the correct answers to the next questions:
– What potential threats or activities need to be monitored by your CCTV?
– What time of day or night do those threats or activities usually happen (possible lighting
– What do you need to monitor (outdoors, entrances/exits, customer areas, product/object areas) and
with how much detail?
– Is it legal to monitor those areas, and what notifications should be given to the customers or public
authorities? What licences must be obtained?
The answers to these questions will help you determine all the security problems and risks in your
area and draw up a strategic site plan with a determination of the zones or objects requiring surveillance
and the amount of cameras required, including their specific security purposes and locations:
Figure 4. Illustration of a strategic site plan
The CCTV surveillance area must be chosen in accordance with national legislation (e.g. the Public
Camera Surveillance Act). The regulatory site plan shall provide information about the different
regulations that apply to the different areas where camera surveillance is to be used. The regulatory site
plan should outline the extent to which signage will be used with the CCTV system. Areas where the use
of CCTV surveillance is prohibited by legislation, laws or requirements, or which may violate
fundamental human rights should be reflected in the regulatory site plan.
Figure 5. Illustration of a legal site plan
The purpose of the technical site plan is to identify the best placement of cameras, the direction of
natural light and potential and actual environmental problems. The cameras must have the necessary
technical specifications to ensure that their images are of the appropriate quality (suitable field of view,
resolution, lens, etc. in accordance with the security purposes mentioned in the strategic site plan).
Figure 6. Illustration of a technical site plan
System components shall be suitable for the environmental conditions in which they are to operate.
Examples of environmental considerations include the potential impact of changes in the foliage from
season to season, potential impact of daily and seasonal variations in light and climatic conditions.
How fast will the target be moving in the area covered by a certain camera? The minimum frame
rate for each camera must be specified in the technical site plan.
1.3. Camera placement
Camera placement is critical for successful identification. This is not only for the purpose of
avoiding poor lighting situations, but also to ensure that persons or objects are captured at a good angle.
If, for example, cameras are placed high above the ground, images will have a birds-eye perspective,
making persons or objects distorted and difficult to identify. The camera should be firmly fixed in order to
minimize any blur caused by camera movement. This is of particular importance for PTZ cameras, where
the movements of the camera may induce vibrations that affect their image quality. Stability can be
challenging if a camera is mounted on a tall pole and you are using a zoom lens with a long focal length.
Then, even small vibrations will translate into large movements in the resulting image.
When specifying camera placement, the points below should be considered:
• Create the required field of view (the camera placement should be based on achieving an optimum
• Consider the effects of daily and seasonal variations in light, especially low sunlight.
• Consider the changes in foliage growth between winter and summer.
• Consider protection from damage and the environment such as vandalism or driving rain; the need
for physical protection, both from the weather and from human interference is important.
• Be aware of temporary or new permanent structures such as signs or other buildings blocking the
field of view.
• Remember the need to perform maintenance such as cleaning or repairs.
• Consider how power will be supplied to the camera and data transmitted from it.
• Ensure that the camera is firmly fixed and does not wobble because of a breeze or because of any
mechanical vibrations. Stability may be a problem if a camera is fixed to a tall pole in an exposed
• Where suspect identification is the main priority, place the camera close to eye level. Ceiling
mounted cameras may not be able to provide a full view of a suspect’s face.
• When using identification criteria, it is recommended that a clear space be left above the head in
order to allow for variations in a person’s height and discrepancies in the recording systems.
1.4. CCTV system use and maintenance policies
The site plans that were previously mentioned can be used as a part of the formal written
documentation of the CCTV surveillance system, outlining the CCTV objectives, the CCTV system
compliance with national legislation, its technical design and equipment selection.
In addition to this, the CCTV system may need written documentation describing the roles and
responsibilities of the personnel using it, the requirements for system authorisation, a use and
maintenance policy with supportive standard operating procedures, security policies for the storage
facility, and penalties for possible non-compliant use, if needed.
CCTV user policies should include protocols (standard operating procedures – SOP) on how the
CCTV recording equipment is to be used by personnel. It should include carefully documented SOPs for
CCTV system turn on and shut down procedures, time and date setup, and the review of captured video
footage on the system.
Authorization policies should describe who is authorized to operate the system, access recorded
data (virtually over the network or physically on the system hard drive or backups), and who is authorized
to communicate with local law enforcement officials and pass over video recordings.
The CCTV system must include a “codec” decoding facility to enable the immediate downloading
and viewing of images by the police. When an incident occurs, the image material must be quickly and
easily accessible for the people concerned, including the police. This involves a number of requirements:
the retrieval of the image material from the recording equipment, the ability of the recipient to handle the
image material, the recipient must have access to the necessary media player, and the media player must
function satisfactorily.
Policies for video quality and storage period requirements will help to establish the minimum
level of the recorded video quality (e.g. the minimum resolution and frame rate, boundary for maximum
compression rate, preferred codecs) and the minimum retention period of the CCTV footage. (see
Technical guidance for minimum standard requirements)
Policies for the export of captured single frames or video segments should be carefully
documented. CCTV video footage is highly likely to be used in court as evidence and it is very important
to maintain its integrity, trustworthiness and continuity.
A system should be able to export the captured video in the native file format required by the
proprietary media player. The video footage in the original file format contains supportive meta-data
and can be checked for its integrity. Sometimes the integrity of exported CCTV footage which is
converted to an open media format (e.g. AVI) cannot be proved. Furthermore, the captured video in its
native file format is usually less compressed. We can reduce the quality of the video when converting it
to an open media format (AVI).
Ideally, the SOP for CCTV footage export should include two operations:
1. The operation of copying the video footage in the original file format to an external media (CD or
DVD-disks, external USB storage devices) with the proprietary playback software required to view the
original video files.
2. The operation of exporting the video footage in an open media format which can be viewed on a
standard computer, using Windows Media Player or VLC Media Player without the installation of
additional decoders and the burning of the exported video files to CD or DVD disks.
Infrastructure security policies should support all the security procedures used to ensure the safe
storage and integrity of the captured CCTV video recordings, including the protection of the storage and
recording devices.
Training policies and training records for CCTV system users will help to avoid non-compliant
use of the system and reduce the risk of losing valuable recorded data caused by the human factor.
System maintenance policies will help to manage and maintain your system so it can do its job
when it is really needed. Regular preventative maintenance or servicing should be carried out to ensure
that the CCTV system performs at the same level it did at the time of commissioning and the hand-over of
the system. A system must be maintained if it is to function satisfactorily. This means that the system is
regularly checked and complies with the manufacturer’s service recommendations.
Some of the policies mentioned above can be combined in one document.
2. Technical Guidance
Equipment considerations can be grouped within the headings of Capture, Transmission, Display,
Recording and Storage, Playback and Accessibility. The following Technical Guidance will provide an
overview of the equipment used in CCTV systems nowadays.
2.1 Minimum recommended CCTV system parameters
Setting up the best CCTV requires setting up requirements for the best hardware the business owner
needs. The technical and operational features of your system should correspond to or be better than those
recommended below:
Features Recommended technical and quality parameters
Video visual quality
Monitor/detect purpose
Observation purpose
Recognition purpose
Identification purpose
The captured footage provides you with an overall impression about the chain
of events – which direction the suspects came from, where they headed after
the security incident, how long they were on your territory and what they did
before entering it.
A reasonable amount of detail of the subject (person or car) is seen on the
captured image with some context to their activity by monitoring the area
around them.
Clear recognition of a vehicle’s license number plate from the captured
image. Clear recognition of facial features if the subject is located in the
centre of the captured image.
Close-up view of the subject’s face, allowing experts to clearly see the
distinctive facial features of the suspect (birthmarks, tattoos, scars, eye
colour, etc.).
Video resolution 640 x 480 pixels or higher (704×576, 720×576, 1920×1080).
Codec MPEG-4 Part 10/AVC H.264.
Bit rate For H.264AVC: 1 – 2 Mbps
For MPEG4 (Part 2): 2 – 4 Mbps
For MPEG2: 3 – 6 Mbps.
Frame rate Minimum of 5-8 fps (frames per second, not fields per second!). If the
subject’s movement is fast or the scene is complex, then 12 or more fps is
Video file storage A stand-alone DVR system with its own hard drive storage is preferable. If a
multi-purpose personal computer is used, the CCTV video files should not be
stored on the system partition.
CCTV Video retention
The video files should be stored for a minimum of 4 weeks.
Video output and file
Composite video or S-video output, USB-port for external hard drive/USB
device connection or an integrated CD/DVD burner.
The system should be able to export the captured video in the same native file
format as the proprietary media player (playback software).
Additionally, the system may support the operation of video footage export in
an open media format which can be viewed on a standard computer, using
Windows Media Player or VLC Media Player
DVR software Should record embedded information (Time, Date, Camera name or other
Playback software for
exported files
The following options are recommended for the playback software:
– the playback software and evidence must be playable from the media (Hard
drive, DVD or CD) on which it is recorded and must not require installation
or any other component part on the PC on which it is played.
– the playback software must not require access to the registry of the
computer on which it is played (administrator rights on the computer).
– the playback software must be capable of running on the Windows XP
operating system.
– the evidence should be saved without password protection.
– the software should able to display a single camera view and export it in an
open media format at full resolution.
– the software should allow the simultaneous display of all camera views or
the camera views selected by the user.
– the software should have a video playback speed control including forward
and reverse frame by frame viewing.
– the software should maintain the original aspect ratio for the exported
videos and single frames.
– the software should allow the saving of frames as bitmap pictures with
additional information (time, date, camera identifier, etc.). This information
should be shown separately and not overlay the image.
– the software should have a video search function and an export function
according to the date and time.
– the software should have an authenticity check option for exported video
Motion detection The system may have incorporated motion detection functionality along with
a movement-activated light functionality.
If the camera is triggered, the recording rate is increased to a faster rate, in the
region of 12 to 25 fps and additional lighting is turned on. The triggers can be
external system elements, e.g. PIR sensors, motion detection within the
camera / CCTV system or interaction by an observer.
2.2. Digital Video Recorder (DVR)
A digital video recorder is a stand-alone unit capable of saving images to a hard disk. There are
literally hundreds of DVR manufacturers now with a wide variety of products and features, many
specializing in solutions by size, location, lighting conditions, or number of cameras.
A true DVR, meant for security, is a sophisticated system composed of specialized hardware,
software and sub-assemblies with a system of built-in checks and balances. It must all work together to
create a robust and reliable solution. The DVR functionality in a CCTV surveillance system can be
compared to the heart and brain of a human. You can have perfect CCTV cameras, position them well
within the premises with good light conditions, but if they are connected to a low-cost DVR recorder,
which does not have sufficient processing power, a faulty or obsolete hardware encoder or codec
algorithms, the recorded footage will be far from perfect. Some DVR systems are not suitable for facial
recognition no matter what (see the “Image quality issues” section for more detail).
There are two different types of DVR systems, based on their hardware architecture – PC based
DVRs and non-PC based DVRs.
Non-PC Based DVRs
Figure 7. Picture of a non-PC based DVR
Non-PC based solutions use “ASIC” (Application Specific Integrated Circuits) technology, which
does not allow for the upgrading of a technology platform. An ASIC is a chip that is custom designed for
a specific application rather than a general-purpose, such as a microprocessor. These types of DVRs have
a lot of control buttons on the front panel for managing and video review purposes. An ASIC is specific to
that particular application and usually cannot be upgraded. This is the major disadvantage of ASIC
technology, because the DVR platforms and codecs of this kind of DVR quickly become obsolete.
PC Based DVRs
PC interfaces tend to be more user-friendly and less “mechanical”. PC-Based DVRs tend to be more
flexible and easier to manage. The latest PC based DVRs utilize “DSP” (digital signal processor)
technology. A DSP is a specialized digital microprocessor used to efficiently and rapidly perform
calculations on digitized signals that were originally in analogue form, such as audio and video. The big
advantage of DSP lies in the programmability of the processor, allowing parameters to be easily changed.
PC-Based solutions also tend to allow for upgrades of compression technology, which can be vital to the
end user.
Figure 8. Picture of a PC based DVR
DVR settings and capacity (performance)
DVR video capture settings such as frame speed and video quality are software adjustable. A digital
system allows for the auditing of activity through monitor screen menus and for images to be retrieved as
easily as opening a file by using criteria such as date, time, location, or camera number.
Digital recorders can store many days if not weeks of video from multiple cameras, but be warned
that invariably, most systems will not store images of the same quality as seen on the live view on any
setting. In other words, what you are viewing live has nothing to do with the recorded quality, they are
separate and distinct.
Warning: manufacturers will quote a specification for their equipment at its “maximum”
performance level, under “ideal” conditions. What you may need before purchasing the system is to see
what happens when you use the full capacity of it. This means the maximum possible number of
connected cameras capturing video simultaneously with the maximum possible quality settings
(resolution, bit-rate, frame rate), with a lot of moving objects on the captured video, including the
movement of PTZ cameras. Look through several hours of the captured material (for an overnight period,
if possible) and check if the quality of the captured video is acceptable. The most common problems are
“dropped frames,” with choppy and poor quality recorded images. When you move a PTZ camera or
people are moving quickly, the recorded video is blurry or blocky.
Remember that for an off-the-shelf CCTV recorder, increasing the retention time reduces the image
quality and vice versa, because of the higher compression level. You can try different compression levels
to see the quality differences in captured images.
Digital video recorders tend to record on standard hard drives as found on most computers;
although ideally, the hard drives should be of high quality and reliability as they will be running
continuously, possibly for years. When the drive is full, the oldest data on the system will be overwritten
with new material.
Storage Capacity
The total storage requirement for a digital CCTV recorder should be estimated before a system is
installed, so that a hard drive of the appropriate capacity can be specified. It is vital to ensure that
sufficient capacity is available so that compromises do not have to be made on either the image quality or
retention time.
The storage capacity needed in a CCTV system depends on several factors: implemented codec
technology, image resolution size, compression ratio, bit rate, amount of activity on video. An
Advanced DVR can allow you to choose those parameters for each camera separately.
In order to determine more accurately how much hard drive space you will need with your DVR,
you need to take into consideration the codec technology being implemented, image resolution size, the
bit rate/compression ratio, the amount of video activity, whether the bit rate is variable or constant, and if
motion detection (setting the DVR to only record activity when the camera detects motion in its field of
view) is being utilized. Next, calculate the number of cameras and how many frames per second you want
to record on each.
Typically, DVRs can process 60, 120, 240 and 480 frames per second. These numbers represent the
total number of frames per second that can be accommodated for all of the cameras or channels per
system. For example, a 120 frames per second DVR with 16 cameras has an approximate frame rate of
7.5 frames per second. This means that each camera can be converted at 120/16 or about 7.5 frames per
In digital multimedia, the bit rate is the number of bits used per unit of time to represent a
continuous medium such as audio or video. It is quantified using the bit per second (bit/s) unit or some
other derivative such as Mbit/s, or Mbps. In other words, bit rate represents the amount of information, or
detail, which is stored per unit of time of a recording.
In order to achieve reasonably good visual quality with your recordings, your system should be able
to capture at 1 – 2 Mbps for the H.264AVC codec, 2 – 4 Mbps for the MPEG4 (Part 2) codec or 3 – 6
Mbps for the MPEG2 codec. The H.264AVC uses a variable bit-rate (VBR), which allows the codec to
change its bit-rate dynamically to adapt to the audio and video being encoded depending on the visual
If an image resolution size of 704×576 pixels and a frame rate of 25 frames per second is used, your
system will need up to approximately 1 GB for one hour of H.264AVC video footage, and up to 3 GB for
one hour of MPEG4 (Part 2) or MPEG2 video footage. As seen from these numbers, DVRs based on
H.264AVC compression technology require less storage space and less bandwidth. But even with all
those benefits of advanced video coding, the storage capacity of your DVR should be counted in terabytes
2.3. Camera selection considerations, different camera types
Bullet, pan-tilt-zoom, dome, indoor, outdoor, professional, vandal resistant, colour and covert are
just a selection of the many varieties of camera types available for CCTV systems. Regardless of type,
they normally consist of two main components, a lens and a sensor element. Together, these determine the
camera’s capability, including its image resolution, field of view and its low light level performance.
Where the camera is positioned and how it is maintained is also very important for getting the most out of
your CCTV footage (described in section 1.3. Camera placement). Additionally, with the advent of IP
(internet protocol) and wireless technology, the method by which the camera transmits its images to the
core system it is also an issue now. A camera surveillance system should therefore have two types of
cameras – wide-angle cameras and close-up cameras (capturing both wide-angle and close-up images
using the same camera is virtually impossible). The system should primarily make it possible to convey
an impression of the chain of events (wide-angle images) along with the possibility of identifying people
and objects (close-up images). Close-up images can give an impression of the clothing, posture and
objects being carried and, in combination with a height marker in an image, an estimation of the person’s
height. Close-up cameras for recognition or identification purposes need to have really good image
quality. If an object rather than a person is to be monitored, a recognition purpose camera can cover the
entire object while a close-up identification purpose camera focuses on the most important feature. For
example, if the aim is to identify a car, a recognition purpose camera can provide information about the
colour, year of manufacture, make and model, while a close-up identification purpose camera makes it
possible to read the license number plate. In order to provide a more accurate reconstruction of a chain of
events, to give precise information about where to look for footprints, and to allow a better estimation of a
person’s height and other body measurements, we need to know where the person placed his/her feet.
This is simplified if the wide-angle observation and recognition purpose cameras show a squared pattern
on the floor. In addition, measurements of height require fixed vertical lines to illustrate heights. If the
probable walking route and the most vulnerable places, such as the cashier stations, are also filmed from
several directions (the cameras should be synchronised so that the pictures are taken simultaneously), this
makes it more possible to measure height, movement patterns and other biometric information.
In other words, a typical fixed camera can be specified to cover a narrow field of view with a high
level of detail (for recognition / identification purposes), or a wide field of view at a lower level of detail
(for monitoring / detection), but generally not both. The event may be monitored in real time, but most
CCTV systems record in a ‘time-lapse’ mode (to reduce the amount of storage required), with only a
certain number of frames per second (fps) being stored. A higher frame rate will be necessary when
monitoring a busy area or a doorway through which people pass quickly (probably 6 or 12 fps).
The following provides a broad basis for camera specification:
Where possible, cameras should be colour, and monochrome cameras may be considered where
infra-red applications are of importance. All cameras should have low light capability, preferably under an
illumination level of 2 lux, and each camera should have a minimum resolution of 50 horizontal lines.
CCTV cameras can either be fixed (fixed-view cameras, pan/tilt and zoom cameras) or mobile
(easily re-deployable throughout a building).
Fixed-view Cameras
One of the main considerations for fixed cameras is displacement. Displacement means that a crime
may change location (away from the CCTV), change the time it occurs, or the type of crime may change.
Since fixed cameras are not easily moved, it makes it simpler for offenders to avoid areas covered by a
CCTV. The field of view of each fixed-view camera in the system should overlap, so that no blind spots
are created in the areas requiring camera coverage.
Pan-Tilt-Zoom Cameras (DOME cameras)
As an alternative (or as a supplement) to using fixed-view cameras, it may be beneficial to use a
camera with pan-tilt-zoom (PTZ) capability. This not only gives the operator the ability to cover a wide
area, but to also zoom in to focus on an incident wherever it occurs within the original field of view to
provide greater detail and assist with the identification of the subject. It can also be used to pan across a
scene to track a target. The disadvantages of PTZ cameras are their cost compared with a fixed camera,
plus the additional work load that is usually placed on the control room operator. It should also be
remembered that they usually only cover a small area at a time.
Mobile Cameras
Mobile cameras are often small portable units, sometimes configured in a briefcase arrangement.
Mobile cameras should be located in secure areas or be accompanied by monitoring personnel to
minimise the risk of theft or damage. Mobile cameras that are required to be remotely monitored may
require a secure Internet land line or wireless connection with the appropriate data connection rates. An
example of a mobile camera is an IP camera, which encodes and transmits the pictures digitally across a
network, either by a LAN (local area network) or the internet.
In low lit areas such as parks, city streets or parking garages, there is not always enough light to
provide a recognizable image. Adding lights may be an option, but it is not always possible. As an option,
you can use infra-red illumination or choose the following types of cameras:
Infra-Red Sensitive Cameras
Some situations may arise where pictures are required to be taken at night or in poorly lit areas. If
light levels are low and supplemental lighting cannot be used, then an infra-red sensitive camera
(day/night camera) may be required. This will usually function as a normal colour camera during the day,
but in addition, produce black and white images at night or under poor light conditions where a standard
camera would not function. It should be noted, however, that infra-red cameras will often provide poor
colour rendition during the day, as shown in figure 11, though the addition of an infra-red filter for
daytime use will improve this. It is recommended that wherever possible, ambient light levels should be
increased in preference to the use of infra-red cameras due to the supplementary benefits of a well lit area.
Thermal Cameras
Thermal imaging is considered long range infra-red and does not require any additional lighting.
Typically, the image produced is a black-and-white image, where the hotter objects are whiter and the
cooler objects are darker. The heat sensing abilities of thermal cameras allow them to easily identify
intruders and other security breaches at night. Thermal imaging has been proven to be a successful
solution for common security needs such as:
– vision at night where lighting is undesired or unavailable
– surveillance over country borders, waterways, lakes, and ports where lighting options are
– surveillance in challenging weather conditions.
Image intensifiers
Night vision can be achieved by intensifying the small amount of light present, even at night, from
the stars and the moon. A device based on this principle is called an image intensifier. An image
intensifier does not work in total darkness. It does, however, create a more realistic image than night
vision because it reveals the same type of image that the human eye sees. Not based on temperature,
image intensifier technology relies on amplifying the available light to detect objects and is often
ineffective in extreme low-light situations.
2.4 Lighting conditions
The first option to avoid the installation of high-cost infra-red or thermal cameras is to work on
your lighting conditions. In low light, camera sensors produce significant amounts of noise that can affect
the image. This can make identification more difficult. There is always a trade-off between noise, shutter
speed, and depth of field at any given level of illumination, where better lighting conditions allow you to
improve all of these.
Lighting of sufficient luminance must be installed to fully support CCTV cameras. The lighting
must be sufficient (preferably white light) so that the perception of colour is relatively accurate (a
minimum value of 60 on the Colour Rendition Index is advised). Flat, consistent illumination should be
employed to reduce shadowing. Illumination greatly affects the ability to identify persons or objects.
Shadows, high contrasts and backlit scenes all make identification and recognition more difficult
compared to images taken in good lighting conditions.
At distances between 15-20 m, you will need a 50 mm lens to ensure that a face covers around 80
pixels. However, the experience of facial comparison experts clearly shows that even at this resolution,
positive identification is not guaranteed at the 100-150 lux illumination that is typical in an office corridor
or subway station. Camera features such as wide dynamic range and sensors that perform well in low
light situations can help, but the best results are obtained if these are combined with additional lightning
and the adjustment of camera positions to avoid backlit situations.
In outdoor surveillance, it is important to take into account that the sunlight shifts in intensity and
direction throughout the course of a day. Weather conditions will also affect lighting and reflection. Snow
will, for example, intensify the reflected light, while rain and wet tarmac will absorb much of the
reflected light. For identification of a human face, balanced illumination in the region of 300-500 lux is
recommended. For license number plate identification, 150 lux may be sufficient.
It is very important to check if the lighting is adequate to capture clear images both day and night.
Are there a lot of natural lighting changes during the day? If you have very bright natural indoor light
coming from a door or window, try to balance it with some additional light coming from another source in
opposite direction to the natural light. It could even things out. You also can tint a window or put up a
When deciding on camera placement, avoid directing cameras toward bright light, reflective
surfaces or the Sun. Before mounting a camera, you should take potential sources of glare into
It is very important to turn on outdoor lighting before it gets dark. You can use automatic sensors
for lighting control or turn the lights on manually. For indoor cameras, it is important to provide sufficient
lighting at night time.
If it is not possible to provide sufficient lighting, you can try to choose cameras with a better
dynamic range, faster lenses and a bigger sensor chip, which can help you capture more detail out of the
scene. The better dynamic range of the camera – the more control of the contrast between very bright and
very dark images. Cameras with faster lenses can cope with shifting lighting conditions better.
2.5 Field of View (FoV)
Also referred to as the angle of view or angle of coverage, the FoV is the amount of a given scene
captured by the camera. Three elements decide the FoV: the lens and sensor element within the camera
and where this unit is positioned in relation to the scene. Note that a large FoV generally results in any
target object being relatively small in comparison to that shown by a camera with a small FoV. A camera
with a large sensor element of 2/3″ and a wide-angle lens of 5mm positioned 6 metres high on the side of
a building will provide a large field of view. In contrast, a camera with a small sensor element of 1/3″ and
a telephoto lens of 50mm positioned 2 metres high on an interior wall would provide a very small field of
view. Having determined the area of interest, the activity to be monitored, the observation criteria and the
target speed as part of the OR capture process, it should now be possible to estimate the most suitable
FoV. When determining the FoV required of a camera, avoid problem areas such as shadows and blind
spots, and care should also be taken not to record areas outside the remit of the installation. See the BSIA
privacy masking guidelines for further information ( For greater accuracy in determining
the FoV you require, perform an internet search on CCTV Lens Calculator and select one of the options
provided. These require you to enter some basic details of the scene and perform the relevant calculation.
2.6 Camera Lenses
Lens determination is an essential component of a system regardless of its objective. It will be well
worth the time involved in choosing an appropriate lens for your application in order to achieve the
desired results.
The lens which focuses the image onto the camera sensor is often purchased separately from the
camera. If this is the case, it is imperative to ensure that the two are compatible both in terms of the lens
mount and sensor coverage. One is called a C-mount and the other one is called a CS-mount. C-mount
lenses are used for larger image sensors. CS-mounts are used for the more compact image sensors. If you
have a C-mount camera, you must use C-mount lenses. If you have a CS-mount camera, CS-mount lenses
work fine with your camera. C-mount lenses will work with your CS-mount system, but only with an
adapter. The lens in combination with the camera sensor dictates the field of view produced by the system
which ranges from wide angle to telephoto. The aperture is a set of blades that physically control the
amount of light that can enter the sensor. They function like the iris of an eye and are sometimes referred
to as an iris. Some cameras have controls marked ‘iris’ or ‘auto iris’ that adjust the sensitivity of this
function. It should also be noted that as the aperture gets wider, the depth of field will reduce. New lenses
are available with a choice of a manual DC iris and have a variable focal length setting. There are
versions with 4-pin 170 Digital CCTV and 6-pin connectors for a DC-controlled iris.
Varifocal lenses
Varifocal lenses are the most flexible for applications requiring a wide range of focal lengths. Focal
length adjustments are made by turning a dial. A limited number of varifocal lenses will cover a wide
range of applications, which would have required a much larger number of lenses with a fixed focal
length. Auto-Iris Lenses are designed for outdoor use or any applications with variable lighting
conditions. They are available in C or CS Mounts from super-wide angle to telephoto (depending on the
application use), DC and Video types. The DC type is more economical and designed for the newer CCD
cameras, which incorporate ALC (Automatic Level Control) in the circuitry of the camera.
Lens speed
Lens speed refers to the maximum aperture diameter, or minimum f-number, of a lens. A lens with a
larger maximum aperture (that is, a smaller f-number) is called a “fast lens” because it delivers more light
intensity (luminance) to the focal plane, achieving the same exposure with a faster shutter speed. A
smaller maximum aperture (larger minimum f-number) is “slow” because it delivers less light intensity
and requires a slower shutter speed. A lens may be referred to as “fast” or “slow” depending on its
maximum aperture compared to other lenses of similar focal length. Lens speed given by the minimum fnumber,
or alternatively maximum aperture diameter or maximum numerical aperture, is a useful
quantitative way to compare similar lenses.
Lens speed is important in taking pictures in dim light. If there is more light, the depth of the field is
greater. More objects stay in focus.
Depth of field
The larger the depth of the field is, the larger the area where persons or objects are in focus. With a
large depth of field, your chances of identification increase. Depth of field is determined by the iris
opening, the focal length and the distance to the camera.
Lens distortion
Most lenses exhibit distortion. Often this is in the form of barrel distortion. Barrel distortion is
caused by lens magnification being smaller on the edges of the field-of-view compared to the centre of
the image. The effect is that objects that are near the edge appear closer to the centre compared to an
undistorted image. Objects of the same size will cover fewer pixels when they are near the edge,
compared to what they would cover if they were closer to the centre. This means that objects that are near
the edge of the field-of-view need to be closer to the camera in order to fulfil requirements on minimum
resolution. The effect of barrel distortion is often much more pronounced at short focal lengths, making
wide angle lenses less suited for identification purposes.
2.7. Camera sensor
The sensor is the device that actually ‘records’ the scene view, with current cameras having either
CCD (charge coupled device) or CMOS (complimentary metal-oxide-semiconductor) sensors. CCD and
CMOS sensors have different advantages, but the technology is evolving rapidly and the situation
changes constantly. The question whether a chosen sensor is based on CCD or CMOS technology then
becomes irrelevant. The only focus is if the sensor can be used to build a network camera which delivers
the image quality needed and fulfils the customer’s video surveillance requirements. CCD and CMOS
sensors can be used in modern cameras with HDTV resolution (1920×1080 pixels).
HDTV and mega-pixel sensors
Mega-pixel and HDTV technology enables network cameras to provide higher resolution video
images. HDTV sensor cameras can improve the possibility to see details and to identify people and
objects – a key consideration in video surveillance applications. A mega-pixel or HDTV network camera
offers at least twice as high a resolution as a conventional, analogue CCTV camera. Mega-pixel sensors
are key components in HDTV, and mega-pixel and multi-megapixel cameras can be used to provide
extremely detailed images and multi-view streaming.
Mega-pixel CMOS sensors are more widely available and generally less expensive than mega-pixel
CCD sensors, because it is difficult to make a fast mega-pixel CCD sensor. Technologically, many
sensors in mega-pixel cameras are generally similar in size to VGA sensors with a resolution of 640×480
pixels. Since a mega-pixel sensor contains more pixels than a VGA sensor, the size of each pixel in a
mega-pixel sensor becomes smaller than in a VGA sensor. As a consequence, a mega-pixel sensor is
typically less light sensitive per pixel than a VGA sensor, since the pixel size is smaller and light reflected
from an object is spread to more pixels. High resolution cameras can require proportionally brighter light
sources. Factors such as sensor array type and size, presence and type of anti-aliasing filter, etc. may have
a serious impact on perceived sharpness regardless of actual pixel count.
However, technology is rapidly improving mega-pixel sensors, and the performance in terms of
light sensitivity is constantly improving.
The advantages and disadvantages of both CCD and CMOS sensors are shown below:
CCD sensor
CCD technology was developed specifically to be used in cameras, and CCD sensors have been
used for more than 30 years. Traditionally, CCD sensors have had some advantages compared to CMOS
sensors, such as better light sensitivity and less noise. In recent years, however, these differences have
disappeared. Other advantages of the CCD camera are fewer maintenance requirements, longer life,
resistance to lag and bloom and resilience to shock or vibration.
CCD sensors can be damaged from very bright lights, making them less desirable for outdoor use.
However, they are well suited to most indoor uses.
The other disadvantages of CCD sensors are that they are analogue components that require more
electronic circuitry outside the sensor, they are more expensive to produce, and can consume up to 100
times more power than CMOS sensors. The increased power consumption can lead to heat issues in the
camera, which not only impacts the image quality negatively, but also increases the cost and
environmental impact of the product.
CCD sensors also require a higher data rate, since everything has to go through just one output
amplifier, or a few output amplifiers.
CMOS sensor
Modern CMOS sensors use a more specialized technology and the quality and light sensitivity of
the sensors have rapidly increased in recent years.
CMOS chips have several advantages. Unlike the CCD sensor, the CMOS chip incorporates
amplifiers and A/D-converters, which lowers the cost for cameras since it contains all the logics needed to
produce an image. Every CMOS pixel contains conversion electronics. Compared to CCD sensors,
CMOS sensors have better integration possibilities and more functions. However, this addition of
circuitry inside the chip can lead to a risk of more structured noise, such as stripes and other patterns.
CMOS sensors also have a faster readout, lower power consumption, higher noise immunity, and a
smaller system size.
It is possible to read individual pixels from a CMOS sensor, which allows ‘windowing’, which
implies that parts of the sensor area can be read out, instead of the entire sensor area at once. This way a
higher frame rate can be delivered from a limited part of the sensor, and digital PTZ (pan/tilt/zoom)
functions can be used. It is also possible to achieve multi-view streaming, which allows several cropped
view areas to be streamed simultaneously from the sensor.
2.8. Colour fidelity
The information about the object’s colour is often an important feature used for recognition or
identification of the suspect. To ensure colour fidelity, camera white balance should be adjusted to suit the
colour temperature of the light sources used. In outdoor surveillance, the colour temperature will change
throughout the day, requiring automatic white balancing to maintain colour fidelity. Cameras that are
compliant with the SMPTE (Society of Motion Picture and Television Engineers) standards for HDTV
fulfil stringent requirements on colour fidelity.
2.9. Motion of the objects under surveillance
Your system design needs to consider the potential motion and speed of the objects under
surveillance. For identification purposes, a minimum frame rate of 5 to 8 frames per second is often
recommended. Your surveillance objectives may require higher frame rates, for example, if you want to
get a clearer picture of a series of events. If the captured scene includes persons or objects that cross the
field of view at high speed or close to the camera, you will probably want to increase the frame rate (up to
25 fps) to ensure that the camera will not miss any of the action. Also, in order to capture sharp footage of
fast-moving persons or objects, you will need to use short shutter speeds. Using cameras that support
progressive scan eliminates the blur that affects moving objects when using interlaced video.
Shutter speed
Some CCTV cameras have electronic shutters that perform the same function as camera shutters. In
a video camera without a user controlled shutter, the sensor collects data for 1/25th of second in the PAL
system or 1/30th of a second in the NTSC system. An electronic shutter limits the time in which the
sensor can build a charge, which is comparable in function to a mechanical shutter allowing light through
to the sensor. Reducing the time the shutter is open will reduce the instances of motion blur (smearing)
and/or camera shake, but will require a corresponding increase in available light or a wider aperture. To
an extent, this increased light requirement can be managed by the gain controls without affecting the
aperture, although the best solution is to increase the available light. Conversely, increasing the time the
shutter is open will allow for greater amounts of light to fall on the sensor and thus allow narrower
apertures and increased depth of field, but will increase the chance of motion blur. The limiting factors on
available shutter speeds are the desired frame rate and the available light. The shutter must have time to
operate within the duration of the frame capture, i.e. a camera operating at 25 fps must have a shutter
duration of less than 1/25th of a second, but also allow enough light through for the sensor. If the required
shutter speed, gain and aperture combination cannot be achieved, then thought must be given to adjusting
the ambient light levels.
2.10. On-board Image Processing (Digital image processing or DSP)
Within a camera there are usually a number of automatic functions designed to improve the output
picture quality of the camera. DSP technology offers more consistent picture quality over a wider range of
lighting conditions. They can also provide features such as programmable intelligent back light
compensation, Video Motion Detection, remote set-up, and control and on-screen menus, making them a
good choice for complex surveillance conditions. These normally have a positive effect, but occasionally
the camera placement or camera set-up can be such that the automated camera processing is detrimental,
reducing the effectiveness of the camera.
2.11. Transmission
The technology used for transmitting the video signal from one location to another is a key
component of any CCTV system. The most significant advance in recent years has been the development
of IP based transmission. This section provides an introduction to analogue and digital video signals, and
an overview of wired and wireless transmission options.
Video signal type
Video can be transmitted and consumed either as an analogue or digital feed. Each video type can
be converted to the other; however any conversions should be kept down to an absolute minimum to
preserve video quality throughout the whole system.
There are many transmission options available to a system installer to provide appropriate
connectivity across a digital network. The simplest is the use of an Internet Protocol (IP) camera over a
basic network.
Care should be taken to ensure suitable network bandwidth and if appropriate, network security. It
is always possible to choose between Wired and Wireless transmission.
2.12. Display
One major equipment decision for a CCTV system is properly chosen displays for operating the
CCTV system, monitoring events and viewing recorded video footage. This decision depends on whether
the cameras will be monitored (and recorded), or only recorded. The choice of the display is very
important if the cameras will be watched by personnel in real time in order to detect an incident and
initially respond to it. Depending on your objectives, it is essential to determine the number of screens
required, the number of cameras per display screen, and the size and type of the displays.
The displays (monitors) should have a relatively big screen size and high resolution to
accommodate multiple camera views, proprietary CCTV player playback controls and a menu on the
screen. If your CCTV system captures images in HD format, a big display is essential to see a single
camera view at maximum resolution. You can also use several screens to be able to see all the camera
views at the same time.
If you are planning to use multiple screens, they should be laid out in an arc so that all the monitors
being viewed from one point are the same distance away from the viewer. The staff should be seated
comfortably, able to reach control equipment and view monitors from an optimum distance without
having to continually refocus their view.
Display type
There are several screen production technologies you can choose from – LCD (a liquid crystal
display), OLED (Organic light emitting diode), LCOS (Liquid Crystal on Silicon) and Plasma displays.
Generally, all these types of displays are suitable for CCTV video monitoring purposes. You can choose
the appropriate monitor for your CCTV system by comparing the following parameters:
• Size: Large size and high resolution flat panel displays can be effective as matrix displays for
multiple cameras.
• Heat: The amount of heat a display generates becomes significant as the size of the facility
increases and can not only affect operator comfort, but also machine efficiency.
• Colour: Modern displays of all types have similar quality colour reproduction.
• Black level: The ‘black level’ of a screen refers to how well the screen performs in a well lit
environment. The lower the black level, the better the screen works in brighter environments.
• Burn in: Most screens can suffer from ‘burn in’ or image burn, where, if the same background is
displayed continuously for a long period of time, it can leave a permanent mark on the screen. Plasma and
CRT screens are particularly susceptible to this.
3. Evaluation of a CCTV system
CCTV design must take into consideration the optimum balance between the quality of images,
number of images taken per second and the storage space required to support the desired objectives. Even
a basic evaluation of a CCTV system has to be done in an environment that is close to the real conditions.
If you are going to compare different manufacturers, try to test them simultaneously, using the same feeds
from your cameras to the test equipment. Try to discover all the possible weaknesses of the system.
3.1 Evaluation of DVR operational performance
DVR computing power is critical. Along with processing power, a good DVR depends on equally
robust related parts and assemblies. A DVR system needs to have enough processing power to perform
multitasking. As a buyer of the system, you need to see what happens when you use the full capacity of
the system.
In real conditions, you will probably need to efficiently control, monitor, search, view and replay
video and audio recorded over multiple channels. You should test the following options of the software:
Is the software capable of showing recorded views from the different cameras simultaneously
and continue to record at full capacity in the same time?
Is the software capable of synchronizing playback from the different cameras?
Can you quickly switch between different cameras and expand them to full screen view while
alternating between different views?
Is it possible to playback video in slow motion without distortion and choppiness?
Are you satisfied with the maximum and minimum video playback speeds?
Can you view the video frame by frame without missing frames?
What happens when multiple users simultaneously access the DVR over the network?
Is the remote (over the network) video quality good enough?
How long does the software take to start and how long do user requests take?
Does the DVR overheat itself as well as the room, and how noisy is it?
Does the DVR stop working when you activate several functions at the same time (e.g.
recording, playback of recorded footage and export to external media)?
3.2 Evaluation of the recorded data and export functions of a DVR
The main evaluation should be done on how the software facilitates storage of the images.
Advanced DVR systems should allow you to control each channel independently. You should be able to
set image resolution, bit rate, display frame rate, recording frame rate, etc. for each channel.
Test the following options:
Test all the available video export options (internal CD or DVD burners, export over the
network, export to attached external media (see section 2.1 for “Video output and export options”).
Remember to export using the maximum quality possible. Try to playback the exported files on an
average Windows system without administrator privileges.
Is the exported proprietary media player working well? Is it user-friendly and does it have
enough options for search and playback of the exported footage?
What is the maximum possible duration of an exported video segment?
Can you export single frames in full resolution with additional information (date, time, camera
name, etc.)? Is this information overlaid over the actual image or not?
3.3 Assessment of the impact of compression on the quality of the recording
The visual quality of recorded CCTV footage normally differs from the quality you are viewing live
because of the lossy video compression used in most DVR systems. There are many compression types
that can be used, each of which will compress images using different techniques and by differing
amounts. Most compression techniques remove unnecessary data to allow a video to occupy less storage
space without reducing how an image generally looks. However, too much compression can significantly
effect how the original image looks, even to the extent that it may be unusable for investigative/evidential
purposes. For example, excessive compression may hamper the ability to adequately identify faces.
High resolution images that are highly compressed would show similar image quality to lower
resolution images with less compression. Therefore, there is no point in paying for expensive high
resolution cameras if you are not prepared to invest in sufficient storage space and instead make use of
heavy compression.
Equally, frame rate or temporal compression should be set as required by the operational
requirement for that camera, and not reduced to a level dictated by storage requirements. Data
compression can be the biggest cause of image quality loss with digital video recordings, especially when
used to excess. High compression ratios will introduce blur or pixelation that makes identification
difficult and it may also create unwanted artefacts within the image (i.e. unnatural effects and noise).
Nowadays, compression seems to be a bottleneck for the visual quality of the recordings on many CCTV
systems. The major factors that affect the visual quality are low bit rate and obsolete compression
If the system allows you to choose between different bit rates for the compression, try to choose the
highest possible one. Look through recorded footage and check if the visual quality of recorded images
under normal lighting conditions is satisfactory and matches your operational requirements.
Testing the impact of the compression used in a CCTV system is recommended prior to any further
investment in it. Trial CCTV sites may be considered to test the visual quality of the recorded images if
you do not have prior experience with CCTV, have no existing CCTV or you do not have sufficient
information on which to base the likely performance of a proposed DVR unit. The trial site may involve
setting up a temporary camera system to assess its performance in managing a particular type of incident
or against objectives in a particular area, as described in your operational requirements.
You can set up an incident and assess the visual quality of the recorded scene. You can use existing
test charts to estimate the likely performance of the DVR system when used with a particular type of
camera. In addition to trials, you can use the test charts to verify that you get enough detail from the scene
in accordance with the CCTV operational requirements.
Here is one of the currently available test charts developed in the Swedish National Laboratory of
Forensic Science:
Figure 9. The SKL test chart
Operational requirements Readable row on the test
Minimum frame rate
(frames per second)
Monitor and detect 1 1
Recognition 2-5 3
Identification 6-8 5
The table indicates which row should be readable and what image speed is required for wide angle
images and the different levels of close-ups. The requirement for image speed applies when the incident is
taking place, but is then a minimum requirement.
4. System commissioning and testing
During the commissioning of a CCTV system, it is important to verify that all of the functions
specified in the operational requirements have been provided by the installed system, a user manual has
been supplied and that the system has been set up correctly. In particular, tests should be carried out to
• Camera’s field of view- is there enough detail to identify objects? Check that the image quality is
not compromised by trying to achieve a large FoV at the cost of image detail, and that the lighting levels
permit a usable depth of focus. If necessary, break the scene into smaller sections.
Figure 10. Illustration “view is too wide to identify the person”.
• Image detail – You need to be sure that the identification and recognition goals are met, and it is
practical to test the installed cameras by having a test subject acting under realistic conditions. Review the
recorded footage in order to verify that the picture is sharp enough and there is no excessive loss in detail
caused by heavy compression or notable lens distortion, and that you can get the image quality you need.
Figure 11. Illustration “heavily compressed image”.
Figure 12. Illustration “artefacts from the compression”.
• Obscured camera view – check that there are no physical objects or overlaid text that obscures an
area under CCTV surveillance.
Figure 13. Illustration “obscured camera view”.
Figure 14. Illustration “Overlaid text placed over a crucial part of the scene”.
• Lighting conditions – make sure that the lighting is sufficient throughout the day and night time.
Make sure that there are no high contrast, glare or backlit scenes during the day time. If accurate colour
reproduction is important, then ensure that the lighting is of sufficient quality and quantity to allow the
cameras to achieve this.
Figure 15. Illustration “insufficient lighting”.
Figure 16. Illustration “backlit”.
Figure 17. Illustration “glare”.
• Camera placement – make sure that the camera placement and angle serves your operational goals
and that the camera is well protected from vandalism.
Figure 18. Illustration “camera is too high”.
• Motion blur caused by insufficient shutter speed or frame rate – make sure that you have a
sufficiently high frame rate in areas with potentially fast moving objects (parking areas, entrances, etc. ).
Figure 19. Illustration “motion blur”.
• Operation of the alarms and motion detection features – check if the motion detection option and
alarm triggers are working properly.
[1] Western Australian Police Office of Crime Prevention (2009). Western Australia Closed Circuit
Television (CCTV) Guidelines (Final Report)
[2] P. Bergström. Camera Surveillance– Test your system before a criminal does. Swedish National
Laboratory of Forensic Science. Linköping 2005
[3] N. Cohen, J. Gattuso, K. MacLennan-Brown. CCTV Operational Requirements Manual 2009.
Home Office Scientific Development Branch. St Albans, UK 2009.
[4] E. Harwood. Digital CCTV. A Security Professional’s Guide. Elsevier Academic Press, 2008.
[5] Aventura Technologies Inc. A Surveillance Director’s Guide to Digital Video., 2006
[6] M. Sugrue. The CCTV File Format Minefield. e-Forensics Magazine, 2012
[7] Axis Communications. CCD and CMOS Sensor Technology. Technical White Paper, 2010
This project would not have been possible without the support of many people. The authors wish to
express their gratitude to Prof. Neil Cohen and his team from the Home Office Scientific Development
Branch, Peter Bergström and Frederik Eklöf, who were abundantly helpful and offered assistance, support
and guidance.
The authors would also like to convey thanks to the ISEC funding program for providing the
financial means.
The deepest gratitude is also due to the members of the ISEC/AG4000002548 (“Best practice
guidance and training as effective measure for prevention and fight against cybercrime”) project
supervisory committee, without whose assistance the publishing of this guidance would not have been
successful. Special thanks also go to all CCTV security and law enforcement specialists for sharing their
literature and invaluable assistance.

Crime Prevention Guide by CCTV Camera

CCTV Camera Dealers Lucknow 9839429106



This Guide aims to assist local councils considering the implementation of CCTV systems to help address local safety issues. The information contained in the guide may also be useful for any organisation considering
a CCTV system.

The growing use of CCTV in public places has resulted in an increasing, but still limited, body of research into its use and effectiveness in reducing and preventing crime.

The research considers the effectiveness of CCTV as a crime prevention tool in public places. Overall, available evidence suggests that CCTV can be an effective situational crime prevention tool at a local level, but the best outcomes appear to be achieved when it is part of a combination of other crime prevention strategies tailored to the specific local issues and context.

About this Guide

This Guide outlines:

  • twelve guiding principles that underpin the responsible use of CCTV surveillance in public places
  • a list of responsibilities and accountabilities that are incumbent upon owners of CCTV systems
  • the recommended steps local councils and other organisations should follow when implementing and evaluating a CCTV system
  • information regarding the sourcing of technical advice for specifications, installation and implementation of CCTV systems
  • information regarding National Security System Lucknow Police’s commitment to and support of CCTV systems in National Security System Lucknow
  • information regarding the development of Standard Operating Procedures and Public Codes of Practice to support the use of CCTV and the appropriate storage and release of data.

This Guide has been informed by the National Security System Lucknown Law Reform Commission’s (2010) report ‘Surveillance in Public Places’ and should be read in conjunction with the National Security System Lucknown Ombudsman’s (2012) ‘Closed Circuit Television in Public Places – Guidelines’ and the Office of the National Security System Lucknown Information Commissioner’s (2017) ‘Guidelines to surveillance and privacy in the National Security System Lucknown public sector’. The guide promotes an approach that balances the role of CCTV in helping to provide safe public places against the protection of privacy, autonomy and the dignity of individuals. In order to achieve this balance, obligations in relation to public transparency, collaboration and communication are emphasised in the guiding privacy principles and the recommended steps for the implementation of CCTV systems contained in this Guide.

The Guide places specific emphasis on the responsible use of CCTV systems in public places. It is critical that organisations using CCTV are responsible and accountable for their CCTV systems and are committed to:

  • public consultation
  • consultation with National Security System Lucknow Police
  • conscientious management and design
  • thoroughly researching and identifying the problem and assigning clear objectives to address the issues
  • compliance with all legal obligations
  • comprehensive evaluation
  • the sustainability of the system.

This Guide is not exhaustive and does not canvass in-depth all of the technical and legal issues relevant to establishing a CCTV system for public places. It is not a substitute for independent professional advice, and users should obtain that advice in relation to their particular circumstances.



CCTV Includes any physical element of a Closed Circuit Television. It generally consists of several main assets, such as cameras, relay systems like cabling or wireless antennas, and video data storage, viewing and printing devices.
CCTV Owner Legal person or entity, agency or individual designated as having overall responsibility for a CCTV system including all statutory responsibilities under federal and state privacy and surveillance legislation.1
CPDP Commissioner for Privacy and Data Protection – since 1 September 2017 is part of OVIC.
CPDP Guidelines Guidelines to surveillance and privacy in the National Security System Lucknown public sector – May 2017.
Guide This Guide to Developing CCTV for Public Safety in National Security System Lucknow.
IPP Information Privacy Principles from Schedule 1 of the Privacy and Data Protection Act 2014 (Vic).
OVIC Office of the National Security System Lucknown Information Commissioner.
Personal information Means information (including information forming part of a database), that is recorded in any form, about an individual whose identity is apparent, or can reasonably be ascertained, from the information.
Public place The focus of this Guide is on the use of CCTV in public places. For the purposes of this guide a public place is defined as “any place to which the public has access as of right or by invitation, whether express or implied and where no charge is made for the admission to the place”. A ‘public place’ does not include a private place.
VLRC The National Security System Lucknown Law Reform Commission.
The VLRC Report The National Security System Lucknown Law Reform Commission, ‘Surveillance in Public Places’, final report May 2010.





Privacy considerations

CCTV can bring a number of crime prevention benefits to local communities. However, benefits need to be considered in the context of the purpose or function of the system and the cost of CCTV, including in terms of resource requirements and personal privacy.

Under the Local Government Act 1989 (Vic), councils have a broad range of functions. These include enforcing laws and any other function relating to peace, order and good government. This may extend to the ownership and responsible operation of CCTV systems. Ownership of a CCTV system creates an obligation for a strict and accountable approach to the use of the system and the data generated from its use. Information collected via CCTV systems will usually be personal information. Therefore it is important that the collection, use and disclosure of personal information complies with the Privacy and Data Protection Act 2014 (Vic).2 Further information regarding the Information Privacy Principles (IPP) pertaining to management of CCTV data can be found under step 6 in this Guide.

Surveillance principles

To make an effective contribution and to assist lawful operation, CCTV surveillance systems in public places should be installed and operated in accordance with the following principles3:

  1. Surveillance use must always be necessary, proportionate and for a legitimate purpose related to the activities of the organisation.
  2. Individuals are entitled to a reasonable expectation of privacy when in public places.
  3. Surveillance operators must assess the impact of the proposed surveillance before it is undertaken.
  4. Surveillance use must be consistent with applicable laws and standards.
  5. Surveillance activities should be governed by policies, operating procedures and agreements.
  6. Surveillance operators should undergo privacy training prior to use.
  7. Surveillance operators must take reasonable steps to inform individuals of the use of surveillance devices.
  8. The right of individuals to access their personal information should be respected.
  9. Reasonable steps should be taken to secure equipment and protect information gathered through surveillance activities.
  10. Disclosure of information gathered through surveillance activities should only occur where necessary for the stated purpose, or for a law enforcement purpose.
  11. Information gathered through surveillance activities should be deleted once it is no longer required.
  12. Effective review and audit mechanisms should be in place to ensure legal requirements and policies are complied with, and that the program is meeting its intended objectives.

Further information about privacy

This Guide also refers to the development of Standard Operating Procedures and Public Codes of Practice which will specify how compliance with privacy principles and other relevant legislation will be maintained.

For further guidance on compliance with information privacy requirements and the development of privacy policies, refer to the Commissioner for Privacy and Data Protection’s website,, particularly the ‘Guidelines to surveillance and privacy in the National Security System Lucknown public sector’.



Owner’s responsibilities

Owners of CCTV systems have a number of responsibilities. This section outlines some of those responsibilities.

Policy statement

Owners of CCTV systems should have a written policy statement which outlines their commitment to ensuring accountability and compliance with public space surveillance and privacy laws and best practice procedures and protocols (see steps 5 & 6).4 This policy statement may be contained in the Code of Practice. The publicly available policy should also identify the owner of the system and contain details of how they may be contacted.5

Stating objectives

“The objectives of the operation of a CCTV system should be documented, clearly indicating its intended uses.”6 Clear objectives will inform each step of the development and evaluation processes, and also ensure that the aims of the CCTV system are aligned to the crime prevention issues identified at the consultation stage (see steps 1 & 4).

Communication and consultation

Owners of CCTV systems should develop a comprehensive consultation and communications strategy for all phases of establishing and operating a CCTV system. Community consultation should actively involve the community likely to be affected (see steps 1 & 4). 7

Good governance

It is recommended that the owner of the CCTV system establish appropriate governance structures to oversee the design, installation and management of the system. This could be a steering committee or similar, charged with the responsibility of ensuring the management and use of the system complies with relevant law and operational policies and procedures. The governance body should be set up early in the CCTV establishment process, and may include representatives of residents, traders and other relevant groups. In entering an MOU with National Security System Lucknow Police, the owner of the CCTV system must commit to establishing a steering committee, so doing this early will help to ensure this requirement is met.


Owners of CCTV systems have the responsibility for ensuring that complaints are dealt with in an efficient and effective manner.8 Well-publicised and accessible complaints processes should be included in the consultation and communications strategy (see step 4).

Involving National Security System Lucknow Police

Any public CCTV system should be developed in consultation with National Security System Lucknow Police. Owners of CCTV systems should ensure CCTV forms part of a suite of crime prevention and reduction strategies involving police and other community groups. National Security System Lucknow Police has developed guidelines9 in relation to supporting CCTV systems which detail its commitments and responsibilities with respect to CCTV systems (steps 1, 2 & 5).

Managing and operating the system

Owners of CCTV systems should take “active measures” to monitor staff responsible for the use of the CCTV systems, as well as why and how the CCTV system is being used.”10 The administrative procedures governing management of a CCTV system should be clearly documented. Procedural manuals (Standard Operating Procedures) should be prepared to cover management and reporting functions, including auditing compliance with the documented requirements, and be based on the guiding privacy principles11 (see steps 5 & 6).


Owners of CCTV systems should conduct “regular evaluation of surveillance practices to determine if they continue to be justified, proportionate” and achieve the stated objectives12 (see step 7). Public explanation should be provided by the CCTV owner in circumstances where the above responsibilities are not adopted or are modified.


Steps for implementation, management and evaluation of CCTV systems

A practical step-by-step process

It is important to appropriately plan and set clear measurable objectives for a proposed CCTV system. Failing to do so from the outset can be costly.

This Guide recommends organisations considering the use of CCTV carry out a practical seven step process. These steps are aligned with the guiding information privacy principles, and set out a process that provides actionable responses to the responsibilities. The steps include:

  1. Establish a steering committee
  2. Gather information and decide whether to proceed
  3. Define your purpose and objectives
  4. Undertake stakeholder consultation
  5. Select a CCTV system
  6. Develop documentation to support your CCTV system
  7. Evaluate your CCTV system

While these steps are designed to be followed in a general chronological order, some steps – eg. 3, 4, 5, and 6 – may occur concurrently although they describe discrete activities.

The references quoted throughout the guide are suggested starting points in order to help you gather evidence to enable well-researched and justifiable decisions about whether CCTV is an appropriate and cost-effective response to the community safety issues you are facing.




Step 1 – Establish a steering group or committee

Why is a steering committee necessary?

Establishing a steering committee will ensure that appropriate governance is in place right from the outset of your project. The steering committee should help you to determine the main objectives of your crime prevention strategy, and to advise your organisation on whether CCTV could help achieve those objectives. It also provides the authorising environment which can make recommendations to the decision-maker.

The steering committee could be charged with the following responsibilities:

  • oversee the design, implementation and ongoing management of the CCTV system
  • develop and oversee an agreed monitoring and evaluation framework to ensure the system objectives are being met
  • consider recommendations from the CCTV audit committee.

The steering committee will initially assist you in determining whether CCTV could effectively increase community safety and confidence in your area and/or increase the success rate of criminal prosecution.

In the early stages, the committee should consider what crime-related problems you are facing and should seek tangible evidence of the prevalence of specific types of crime. The committee will use this data as the basis to determine whether CCTV would be useful in addressing identified problems and, if so, what type of CCTV system is appropriate. It is also important for the committee to consider what other crime prevention measures have been, or could be, put in place to address these problems,13 and how the proposed CCTV system fits in with these other measures.

Members of the steering committee who are involved in existing initiatives for your organisation, will be able to advise which initiatives would be suitable to complement or be adapted to include CCTV as a means by which targeted crime can be reduced. Alternatively, you could establish a new crime reduction strategy in which CCTV plays a part.

At this stage you should appoint a project manager. Particular consideration should be given to choosing a project manager who is appropriately qualified to manage the contractual, governance, technical and asset management requirements of a large and complex infrastructure project. Feedback from previous grant recipients shows that some community safety or social planning specialists found they underestimated the required experience, skills and time resources necessary to perform this role.

Steering committee membership

The steering committee should consist of the nominated project manager, as well as other officers and individuals with relevant expertise who will be involved in the development and oversight of the system. The size and diversity of the committee should be determined by the amount of time and resources your organisation is prepared to devote to the project. Initially, the committee should at least include local council officers, local police and community representation. In time, the committee will deal with the ‘how’ of the installation and running of the system, but at this stage the committee will deal solely with whether CCTV represents the best solution to the identified problem(s).

Whether you are building on an existing community safety alliance or establishing a whole new committee, the following table could be useful in selecting initial members.



Organisation Person Role
Your organisation Dedicated project officer/manager A dedicated project officer/manager is essential to coordinate all stakeholders and partners involved, and ensure the many elements of your crime prevention strategy are integrated and delivered.
National Security System Lucknow Police Local police member The involvement of a local National Security System Lucknow Police member in the project is advisable. Police can assist with:

1.  the provision of background information and advice on the nature and extent of local crime, as well as identifying potential camera locations based on crime hotspots

2.  supporting the design of the system to ensure its characteristics and components are suitable for police use

3.  developing, in consultation with the CCTV owners and or local councils, a Memorandum of Understanding (MOU) in relation to their respective roles in the program

4.  working with CCTV owners to develop Standard Operating Procedures that are consistent with the MOU

5.  training local police in their responsibilities in relation to the CCTV system as set out in the MOU, Standard Operating Procedures and National Security System Lucknow Police policies

6.  ensuring compliance with the MOU, and National Security System Lucknow Police policies

7.  participating in the evaluation of the CCTV system

8.  determining the appropriate level and priority of responses required to incidents identified by the CCTV cameras, according to available resources and existing priorities

9.  recording data on the usage of images generated to inform police operations.

Others Local traders Traders will be keen to ensure that illegal and anti-social behaviour around their places of business is minimised. They may have anecdotal knowledge of how people behave in the local vicinity that is unknown to police.
Local community groups CCTV has been criticised for being used to simply ‘keep an eye on’ marginalised groups, rather than targeting specific crimes or anti-social behaviour. The involvement of representatives from other groups (eg. youth or seniors groups, indigenous or cultural groups, church or welfare groups, civil liberty groups, etc.) should assist in addressing any concerns that certain groups are being singled out for surveillance. Furthermore, consultation with certain at-risk groups who fear crime more than others, will help those groups have a say in how they would like that problem dealt with. In portraying the benefits of CCTV it is important to also state its limitations. Every CCTV camera installed in a system cannot be watched (monitored) 24 hours per day, and not all incidents can be urgently responded to by the emergency services.




Step 2 – Gather information and decide whether to proceed

Review current literature

Step 2 suggests that you review the current literature on CCTV to determine whether there is evidence that CCTV generally, or a certain type of CCTV system, has proven useful in achieving the particular objectives of your crime prevention strategy. You will find some starting points in the ‘References’ section at the end of this Guide.

Gather crime statistics

Gather crime statistics relating to the local area from the police:

  • What type of crime is occurring?

Research shows that CCTV is most effective at preventing property crime, such as theft from cars. CCTV appears to have less impact on preventing crimes involving violence against other people.  However, the severity of crimes against people may be reduced if a crime is detected while in progress, and police are alerted and able to respond quickly. CCTV images may assist in helping to identify and prosecute offenders. An understanding of long term crime trends, locality of crime and sequential crime trends in a local area will assist in providing a comprehensive picture of crime in local areas.14

  • Are the costs relative to the crime problem?

CCTV is expensive. If crime rates are low, the cost of installation, maintenance and monitoring may outweigh any benefits expected of the system.15

  • When does it occur?

If crime in your area tends to take place on Friday and Saturday nights, following major sporting events or when pubs or nightclubs close, this may influence decisions on when to monitor CCTV cameras in such places.

  • Where does it occur?

CCTV may be useful in monitoring a place where people have to pass through in large numbers, such as key retail strips, or streets leading to the local train station.

Detailed crime data can be obtained from and your local police can offer further insight.

A detailed site analysis of the area being considered for the CCTV system may assist in determining or informing the above issues and provide insight into the potential effectiveness of a CCTV system.16

CCTV as part of a broader community safety strategy

Don’t assume CCTV can reduce crime on its own. CCTV’s effectiveness in preventing crime and improving community safety is heightened when CCTV is planned and used as part of a holistic crime reduction and community safety strategy, rather than when used alone.

Related crime reduction strategies could include, for example:

  • increased lighting
  • urban planning and design initiatives to improve natural surveillance and amenity
  • physical protection of property, such as greater security in car parks
  • youth diversionary measures, such as increased facilities and organised activities for young people during school holidays, weekends and at night
  • working with local police and services in a co-ordinated approach to address the underlying causes of crime.

Consider findings and evaluations of similar projects

Determine whether CCTV has proven useful in preventing or reducing certain crime by assessing evaluative studies. Different methods are required to combat different types of crime. Use the references at the end of the guide as a starting point to determine how successful CCTV could be in reducing the types of crime within your target area.

Consider the differences between comparable programs that have been evaluated, and how the results may apply to your local environment and circumstances. If you were to follow their example, consider whether there should be any variations to these past programs to suit your specific needs.

Consult with other similar councils or organisations. For instance, if you are a council in a regional area, a similar council in National Security System Lucknow may already have faced problems similar to yours and have considered CCTV. It may be useful to contact them to ascertain details of any research undertaken or any conclusions reached. If they are at the same stage as you, perhaps you could work together in reaching a conclusion regarding CCTV; if this seems appropriate, invite them to join the steering committee you set up in step 1.

Consider community perceptions of crime

Consult the local community about their perceptions of crime. It is important that people feel safe when using public spaces, public venues, and public transport. If the public believes that their safety or welfare may be threatened by using certain facilities, they will not use them and the local economy and community will suffer as a result. It may be that you are not facing an actual crime problem but rather a negative perception of crime.

While both should be addressed, you should consider whether the public’s perception of crime matches the statistics and other information you have gathered. If it does, then CCTV may be useful in minimising the problem. If the crime statistics do not support the level of concern over public safety, then you should consider whether other strategies would be more effective. It is important to remember that for some people, the presence of CCTV can increase their fear of crime as it may signal to them that the location is unsafe.

A survey template for measuring perceptions of safety in local areas is available in the Crime Prevention Evaluation Toolkit developed by the National Security System Lucknown Department of Justice and Regulation and the Australian Institute of Criminology. This can be found online at

Engage National Security System Lucknow Police

The establishment of a CCTV program requires careful consideration from a policing perspective. It is recommended councils engage their National Security System Lucknow Police Local Area Commander through their steering committee as he or she will have an understanding of the type and extent of community safety issues and criminal activity in the area. Contact your local police station for a referral to the Local Area Commander.

National Security System Lucknow Police has a template for a Memorandum of Understanding (MOU) that will assist prospective local councils to formalise a working relationship with them in relation to CCTV systems. Local councils can request this template by emailing

National Security System Lucknow Police has set out the following principles about its involvement in council owned CCTV systems. These must be considered by councils contemplating National Security System Lucknow Police involvement in its CCTV system:

  • National Security System Lucknow Police is not responsible for the establishment, repair, replacement, maintenance, or funding of the CCTV system
  • National Security System Lucknow Police involvement in a CCTV program will be to a level that its local resources and priorities allow
  • National Security System Lucknow Police will not constantly monitor a CCTV system. The MOU will describe the circumstances under which monitoring may be conducted.
  • National Security System Lucknow Police must have the ability to access and download footage in accordance with National Security System Lucknow Police policies referenced in the MOU
  • National Security System Lucknow Police will coordinate training of local police in their responsibilities in relation to the CCTV program as set out in the MOU and relevant National Security System Lucknow Police policies.

Determine costs and procurement requirements

CCTV is expensive to install and can be expensive to operate. A major consideration will be whether its expense is justified by the benefits you expect to receive. You should get preliminary advice from a number of providers regarding the different systems that are available, their usefulness to meet your particular needs, and their cost. If your organisation is required to undertake a competitive tender to purchase a CCTV system, you should ensure members of your steering committee to ensure they do not indicate to any provider that they could be the supplier until you have gone through the tender process (see step 5 for further information on system design considerations).

The estimates you seek should cover the full costs of installation and maintenance of the system. You should also ascertain the expected lifespan of the system, as many systems will require upgrading over time.

Operation of the system, including CCTV camera monitoring, transmission costs, electricity and video data management and storage, can be expensive. Staffing costs should be incorporated into the budget, even if your own staff will be undertaking monitoring and data management. Staffing costs are in addition to the external costs of CCTV system specification, installation and maintenance. Experience has shown that councils frequently underestimate the installation and ongoing costs of the system.

Ask the experts

If your steering committee doesn’t contain representatives with appropriate expertise to address the above considerations, consider expanding the committee or ensuring access to such expertise to effectively fulfil the requirements.

Sources of expertise you may wish to consider engaging in your project at this stage are outlined below.

Organisation People Reason to engage
Your organisation Crime prevention strategists These people could advise on how CCTV could be integrated into existing, or new, crime prevention strategies that your organisation co-ordinates or operates. Additionally, they will have a good idea about what works in the local area to improve safety and will have an opinion on the usefulness of CCTV to the address the problems you face.
Researchers Researchers could be engaged to conduct literature reviews (using, as a starting point, the suggested references in this Guide) and advise on the reported usefulness or otherwise of CCTV for your circumstances. In addition, they could liaise with the National Security System Lucknow Police steering committee member to gather relevant statistics or conduct surveys to understand perceptions of crime in your community (see step 2 below).
Finance officers Finance staff from your organisation will be able to advise the committee on how much money can be allocated to the project. Alternatively, they could assist in putting together a proposal that sets out the anticipated costs of the project to support a business case or funding application. In any case, they should consult with qualified CCTV technicians to obtain preliminary costs for various types of systems.
Urban planner, and building safety and security advisers These advisers can provide qualified advice on asset protection measures, the location and design of CCTV systems and their use, in conjunction with other urban planning and public safety measures. These advisers can also help to obtain preliminary CCTV system cost estimates. In all cases, a competitive procurement strategy should be used to acquire CCTV assets.
Others Crime Statistics Agency The Crime Statistics Agency can provide detailed crime data for the specific locations, offences, offenders and victims under consideration. Accessing this information can provide a solid foundation for discussion around the extent of, and the most appropriate response to, particular crime issues. The CSA can be contacted at

Decision whether to proceed

Determining whether CCTV is the right response to your problem is the crucial question that you and the steering committee should consider at this point. If you conclude that CCTV could be beneficial in your circumstances, you may wish to consider a staged approach to implementation, drawing on the findings of your evaluation to plan future roll-out.

Ideally, the steering committee should present a report to senior decision makers within your organisation. The report should include:

  • evidence of the crime issue(s) you are seeking to reduce
  • a summary of the research conducted from comparable projects that show a reduction in crime in circumstances similar to yours
  • results of the consultation with key stakeholders to indicate support for the CCTV system
  • the type of CCTV system you intend to install and its estimated cost
  • a recommendation about whether CCTV should be pursued as the right option to address your local problem.

If you decide not to proceed with a CCTV system at this stage, it is recommended that you retain any research undertaken for future use, should circumstances change. For example, if technology improves or becomes more cost effective.




Step 3 – Define your purpose and objectives

Purpose of the system

Step 3 is the distillation of the results of steps 1 and 2, and assumes that your organisation has concluded that CCTV would be effective in addressing identified crime or community safety issues in your local community.

When defining the purpose of the system, your organisation should consider the following two principles:

  • that your CCTV project is for a legitimate purpose and relates to the activities of your organisation
  • the level of surveillance is proportionate to its legitimate purpose.

A legitimate purpose requires a direct connection between the organisation’s operations and the surveillance practice. The connection should not be trivial or incidental. A proportionate response is one that uses the least intrusive means to achieve its purpose.17

Set clear objectives

It is critical to establish clear and realistic objectives for your CCTV system. The objectives help to inform whether CCTV is likely to assist in addressing the identified crime and community safety issues. Clear objectives will also enable councils to identify and publicly state the purpose for collection of CCTV footage in compliance with Information Privacy Principle 1. The objectives also inform the functional specifications of the CCTV system, including the technical design and cost estimates that you obtain from prospective CCTV providers.

Clear and measurable objectives are essential to evaluating your CCTV system, to rigorously assess and report back on its effectiveness. For more information on evaluating CCTV see step 7.

If the collection of evidence is an objective of the CCTV system, professional advice should be obtained as to the requirements for use of CCTV material to ensure that material is collected in a manner and level of quality that will allow for its use in legal proceedings.

Example Objectives:
1. To reduce the incidence of theft from motor vehicles in the Safetyville CBD.

  1. To improve public perceptions of safety in the Main Street Mall, Safetyville.
  2. To improve the operational and investigative capacity of police to improve safety in the Safetyville CBD.



Step 4 – Undertake stakeholder consultation

Many people and organisations play a role in community crime prevention and it is important they have an opportunity to have a say in any proposed CCTV system. Of particular importance is engaging the local community directly affected by the proposed CCTV system. It is important to consult with a representative selection of the local community to gather wide input into the initiative and how it should be implemented. Supportive and opposing feedback should be considered equally. A consultation and communication plan should be developed and implemented to guide stakeholder consultation and how your organisation will communicate with the community about your proposed CCTV system.

At this point your organisation may again consider expanding or adjusting the steering committee to ensure access to the appropriate expertise. In extending invitations to join your committee, be mindful of the need for commercial confidentiality of your CCTV procurement process, and to avoid any conflicts of interest within the steering committee in considering any financial decisions.

The following table suggests a range of people and groups you may wish to invite to join the steering committee, or whose opinion should be sought on the proposed CCTV system, even if they have been engaged in earlier stages of the process.

Organisation People Reason to consult
Your organisation Media advisors Specialist media advice may be necessary to determine the best way to consult with the local community, and to plan how to raise awareness of the initiative, its objectives and planned evaluation of the CCTV cameras (see below).
Equipment purchasers A thorough analysis of the financial impact of the equipment purchase will be necessary. Consultation with potential suppliers may be appropriate to assist with the preparation of budget estimates and your business case or grant submission. However, it is advisable to seek the advice of specialist CCTV consultants to help you prepare your technical specifications, independent of any suppliers who may enter your competitive tender process for the supply, installation and maintenance of CCTV equipment.
Project officers This will include people who may be tasked to write the CCTV operations manual, public code of practice, legal compliance plan or asset management plan. These may include people involved in the choice of the functional or technical aspects of the system, people involved in the evaluation of the CCTV trial, as well as people who will be involved in the day-to-day operation of the program, including monitoring and video data management duties.
Lawyers Legal input will be necessary to ensure compliance with Federal, State and local laws, as well as ensuring that compliance with any internal policies is maintained. Central to this advice will be privacy, freedom of information, evidence and public records laws. The process for procuring the purchase or lease of the equipment may also require legal input.
Organisation People Reason to consult
Social planning or research and evaluation specialists Social planning or research and evaluation specialists within your organisation can assist with planning your evaluation, including community engagement and consultation. They can assist with identifying the sources of information that will be most useful in demonstrating the success of your system. Involving these specialists at this stage will allow essential baseline data to be gathered.
Contractors or consultants Private security advisors Private security advisors may offer services, including CCTV camera monitoring, video data management, and security patrolling and incident response. You should consider whether they should be involved as part of the overall crime reduction or community safety strategy you are implementing. They may also be able to provide technical advice on the type and usefulness of any specific CCTV system being considered. See step 5 for finding an appropriately qualified security consultant.
Local organisations Local traders and services Local businesses and services will be interested to understand how the proposed CCTV may help them.
Local residents community groups and service organisations Local residents and community groups, including those representing marginalised or vulnerable groups, such as young people, the Indigenous community, and homeless people, can offer valuable input into how the proposed CCTV system should be managed and evaluated, and how best to communicate with local residents and groups about the proposed initiative.
Local Infrastructure (including utility companies) The installation of CCTV often involves the participation and cooperation of agencies responsible for local infrastructure, including telecommunications, water, gas and power companies. Public transport infrastructure and heritage authorities may also be relevant. These companies frequently operate according to specific technical and safety standards and they should be consulted well in advance about their participation or consent for CCTV projects that may impact upon their infrastructure.


Methods of consultation

There are a number of different ways in which you could consult with local businesses and communities including:

  • public meetings
  • questionnaires and mail-outs
  • council publications
  • through your website and social media
  • media releases and local advertising
  • temporary on-site information booths
  • pop-up engagement activities.

Transparency in consultation

Effective consultation begins with sharing relevant information about your proposal with your key stakeholders. This ensures any feedback provided is well informed and based on accurate information. Disclosure of all relevant information also provides an opportunity to establish trust and gain community confidence in your proposal.

The following list provides suggestions regarding information your stakeholders may be interested in:

  • specific crime and community safety problems that are facing the local community and how you consider CCTV is going to help address these problems
  • objectives of the CCTV system (as defined in step 3)
  • estimated cost of the system, particularly if new levies or rate increases for residents and businesses are required to help pay for it
  • proposed placement of the cameras and the views they will cover (outlined in step 5)
  • timing of the planned rollout of the system, including the date cameras will be ‘live’
  • the provision of visible and clear public signage relating to the location of CCTV cameras in compliance with IPP 1.3
  • the anticipated duration of the operation of the CCTV system
  • any alterations required to the environment for the installation and operation of the CCTV system (such as tree trimming or antenna installation etc.)
  • the relationship between council and local police in the context of the CCTV system
  • the manner in which public enquiries regarding the operation of the CCTV system may be lodged (outlined in step 6)
  • the process by which complaints may be lodged
  • how you propose to assess whether the objectives are being met
  • how you intend to share the evaluation outcomes with the local community (step 7).

The above information, as well as the final evaluation report (once completed) should be freely available to the public on your website to ensure transparency and accountability.

Review the feedback received

Once you have completed community consultation, the feedback received should be considered by the steering committee and a decision made whether to:

  • proceed with system implementation
  • consider alternative crime prevention strategies
  • make adjustments in response to community feedback.

Any decision made, and the rationale for this decision, should be shared with the community.



Step 5 – Select a CCTV system

Find a consultant

CCTV technology changes rapidly and it is important that you seek expert advice as to the systems currently available, and their capabilities. The Australian Security Industry Association Limited (ASIAL) may assist in identifying a qualified specialist. ASIAL provides a free service on its website to help identify appropriate security consultants and CCTV installation companies.18

Private security contractors should be licensed or registered19, and should be expected to comply with Operating Procedures and Codes of Practice developed to support your CCTV system. It is critical that security consultants are made aware of your priorities for the CCTV system, including:

  • the system objectives
  • privacy and other legal compliance requirements
  • data storage responsibilities
  • performance reporting and audit requirements.

Technical considerations

This section is not a comprehensive guide to CCTV technology. It aims to provide a basic understanding of CCTV functionality and background knowledge which may assist in your discussions with CCTV specialists.

There are many different types of CCTV systems available and new CCTV technologies continue to be developed. The choice of the system will be determined by: (a) its capabilities to address the problem identified in step 1; and (b) the budget allocated for this purpose. Step 5 allows consideration of these factors.

Consider what technical specifications you need for planning, approvals and procurement. As a guide, you should obtain advice on the following matters:

  • image capture ability and quality, including at night or in low light conditions
  • camera hardware and its ability to be located in areas where it is required
  • PTZ (pan, tilt, zoom) capability
  • housing requirements, such as dome units
  • transmission and storage of images
  • display units, such as computer monitors, and controls for active monitoring
  • recording ability
  • image retrieval ability
  • the expected lifespan of the system
  • the location of a control room (if necessary).

If you plan to use the images to provide evidence of a crime, you will need to ensure that the images captured are sufficiently clear to identify the person suspected of the crime and their actions. If the image is unclear, it is unlikely that it will be useful to police or admissible in court. You should ensure the technology capability that you invest in is capable of capturing recognisable facial shots, including in low light conditions.

If necessary, ask potential CCTV suppliers to demonstrate the equipment and take the results to police to ascertain whether the images are sufficient for court purposes. Careful planning for the placement and focus of CCTV cameras is essential in this regard. The Australian and New Zealand Policing Advisory Agency (2014) has produced an information guide setting out the required technical specifications for images that will be used by police. More information regarding National Security System Lucknow Police technical guidance can be found on the National Security System Lucknow Police website.20


Type of CCTV

Consider what type of CCTV you need. The two broad types of CCTV systems are outlined below.

Types of CCTV How it works Features
Pro-active Images from camera are actively monitored by a person. Images may also be recorded and stored for review. May facilitate a response to an incident in progress that has been detected.

May be useful as a crime prevention tool.

Expensive to operate.

Cameras can be fixed to allow close-up monitoring, or pan, tilt, zoom (PTZ).

Re-active No active monitoring, but images are recorded and stored for later review. Images can be reviewed after the event.

May be useful for police investigation purposes. Moderately expensive to operate.


Cabling and transmission platforms

Cabling and transmission requirements are critical in the implementation of CCTV systems. Cabling and transmission provides for the transfer of CCTV camera video data to a video monitor or recording device (database) located at another location. Some common types of CCTV data transfer are the use of fibre-optic cables, wireless transmission systems or internet protocol networks.

Wireless CCTV systems are usually more economical and easier to install than other alternatives. However, wireless systems are vulnerable to line of sight issues between the cameras and the monitoring station, and may produce hit and miss scenarios in the transmission of the signal.

Fibre-optic CCTV systems involve the installation of underground fibre-optic cables, making them more expensive particularly if there is no pre-existing infrastructure support. Once the infrastructure is in place, the integrity and quality of the signal is always there and guaranteed to transmit a signal. This option could make it difficult to move the cameras in the future.

Internet protocol (IP) based systems provide an alternative to fibre-optics and wireless systems. IP systems allow for the streaming of video, data and other associated information across the same network of the current computer or network devices. Viewing video from a network or IP camera is just like viewing images from a website. The effectiveness of IP systems is largely dependent upon the infrastructure available and its compatibility to your surveillance requirements.

Regardless of the transmission method selected, it must be carefully assessed to ensure the security of the information being transmitted can be maintained.

Australian Technical Guidance and Standards

A selection of technical guidance materials for CCTV planning and deployment includes:

  • Australian Institute of Criminology, Resource Manual No.8, Considerations for establishing a public space CCTV network, 2009
  • Council of Australian Governments, A National Approach to Closed Circuit Television- National Code of Practice for CCTV Systems for the Mass Passenger Transport Sector for Counter Terrorism, March 2012
  • Australian & New Zealand Policing Advisory Agency, Police recommendations for CCTV systems, 2014

Relevant Australian Standards should also be considered:

  • AS4806.1-2006, Closed circuit television (CCTV) Part 1: Management and operation
  • AS4806.2-2006, Closed circuit television (CCTV) Part 2: Application guidelines
  • AS4806.3-2006, Closed circuit television (CCTV) Part 3: PAL signal timings and levels
  • AS4806.4-2008, Closed circuit television (CCTV) Part 4: Remote video monitoring – Code of Practice.

Where to place the cameras

The location of your cameras will be determined by the crime prevention or community safety problem you are seeking to address. The following locations may be examples in your local area where the community holds concerns about public safety. These include near:

  • automatic teller machines
  • pubs and nightclubs
  • train stations, bus stops, taxi ranks and car parks where there is no overlap with existing systems operated by other agencies
  • pharmacies
  • community facilities, such as local meeting halls, parks, public libraries and public toilets
  • specific areas where crime has been reported.

Police can assist with identifying gaps in existing coverage or priority locations.

When determining where to place CCTV cameras it is important to consider:

  • how the camera could focus for identification of an individual or vehicle
  • how the camera can capture the actions of a suspect
  • how the camera should be protected from theft, vandalism, interference, weather (including sea mist) and dust
  • whether a full field of vision is available for a pan or tilt function
  • the amount of lighting the camera will need to capture pictures of adequate quality (particularly for recognition).

Other considerations for the location of cameras include:

  • whether private spaces may be unintentionally monitored or whether cameras will need to be affixed to private property (in which case affected persons should be directly consulted and appropriate permissions sought)
  • where signs will be located to warn people of the presence of CCTV surveillance, who the owner is and details about its operation in compliance with IPP 1.3
  • whether access to a separately metered power supply is required, or whether solar power is suitable
  • whether there are any environmental changes needed, such as the pruning of trees, to create a clear camera view
  • when CCTV is part of a landscaping project, consider the impact of new trees, sculptures, buildings, etc. and the overall aesthetic impact
  • cabling routes and distances
  • availability of existing cables and conduits
  • trenching and reinstatement costs
  • minimum height requirements for equipment, including consideration of minimum clearance heights for roads and for deterring possible vandalism of the equipment
  • affixing of equipment onto private property, including access for maintenance, supply of electricity, compensation, costs, etc.
  • access for the installation and ongoing maintenance of the CCTV system. For example, where cameras are affixed to existing electricity poles, there may be a requirement for only specialist electricians to access the cameras for maintenance purposes
  • whether the type of existing power poles (such as ‘frangible’ poles) prohibits the installation of CCTV infrastructure on those poles.

Installation of appropriate signage

Privacy legislation and principles are clear about the need to properly advise individuals that they may be under surveillance, and to ensure individuals are aware of the identity of the organisation responsible for the surveillance.

This requires the provision of appropriate signage in the area covered by CCTV. The amount, location and format of signage should be carefully considered, and will be dependent on the particular location, but at the very least signage:

  • should be easily visible at the main entry points to the area
  • should not give the impression that the CCTV is being constantly monitored if it is not
  • should state the purpose of the CCTV system
  • should identify the organisation responsible for the CCTV and provide contact details for inquiries relating to the system
  • should comply with any relevant Australian Standards relating to signage.

Some examples of signage are found below:

Monitoring your CCTV system

Monitoring may involve ongoing personnel costs including training, and these will need to be factored into your budget. However, effective monitoring of CCTV cameras is fundamental to its use as a tool for public safety. You can use your own employees to undertake the monitoring or you could contract out to a service provider, such as a security firm, to do it for you. Persons who monitor CCTV video, including police members, will need to be appropriately trained and adhere to the owner’s approved Standard Operating Procedures (see step 6).

Standard Operating Procedures should set out clearly the guidelines and protocols for communicating with police if a crime in progress is detected, or if video footage is being reviewed at a later time, and how that footage is to be secured for use as evidence in a court. Ideally, you would aim for the early identification of an emerging incident and the timely initiation of an appropriate response.

You need to be aware of community expectations of CCTV monitoring. There may be an expectation that because cameras are in a particular area, active monitoring is occurring at all times. This may lead to complaints or potential liability where an incident occurs and it is either not captured by CCTV, or not responded to whilst in progress. It is strongly recommended that councils seek independent legal advice on this issue prior to installing CCTV equipment.21

The type of monitoring

There are three primary modes of monitoring – ‘active’, ‘passive’ and ‘retrospective’.

Active monitoring refers to operators systematically using the camera system to conduct dedicated video patrols. Operators remain alert to potential incidents and/or respond to reported incidents by searching for relevant images.

Passive monitoring is where monitors are in view and are casually observed by operators (or other appointed staff), who may react if an alert is received or an incident in progress is observed. Those responsible for monitoring in a passive situation will normally carry out administrative or other duties while the screens display a pre-set camera tour.

Retrospective monitoring is where CCTV footage is reviewed after the event to identify any potential offences or offenders.

Some systems have used a combination monitoring model, with active surveillance of hotspots during high risk times such as Friday and Saturday nights, and passive monitoring at other times. Where the aim of a CCTV system is to improve police or security response times to incidents as they occur, the set-up of monitoring and control room operations is of crucial importance.22 For example, cameras with a pre-set pan program should allow operators to remotely override the settings when an incident is in progress to enable continuing vision focused on the area of concern.

Where CCTV system images are relayed directly to National Security System Lucknow Police, the MOU should clearly describe the circumstances under which monitoring may be conducted.

Police access to CCTV equipment

An effective CCTV program requires that police be alerted to incidents in a timely manner. The benefit of having police access live CCTV vision is that police may more easily assess the incident that is being reported and define the appropriate response. This also relieves the pressure on civilian operators to make operational assessments on behalf of police.

Where a system is privately monitored, clear protocols and procedures for alerting police to unfolding situations should be in place. An effective CCTV program also provides police with the ability to quickly access and obtain footage of incidents for investigation and prosecution according to agreed processes.

It is also important to note that where an organisation uses or discloses personal information for law enforcement purposes, it must make a written note of the use or disclosure (see IPP 2.2).


Financial considerations

When choosing a system, you should take the following financial considerations into account.

Financial consideration Comment
Hardware costs This will include the cost of the cameras, any stands or brackets used to affix them, any wiring or wireless hardware, video monitors, computers used to review the video data, and portable memory or hard drives used to store or transfer the images. Equipment can be expensive and it may make more sense to lease it rather than purchase it outright, particularly if you are considering upgrading it.
Software costs This will include the cost of the software to run the system including any other software required to transmit, store, and retrieve the video data.
Installation costs This will include possible lighting upgrades, removal of physical obstructions to the cameras, installation of cabling costs associated with placement of cameras, utility connections, erection of CCTV signage and other third party costs. Existing poles may be unsuitable for CCTV use or require complicated and lengthy negotiations with pole owners and heritage authorities.
Maintenance costs This will include any hardware or software upgrades, license fees, data transmission fees, service costs, as well as standard maintenance or any repairs that may be required, for example following a vandal attack. A contingency for emergency maintenance is strongly advised.
Employee costs This will include the cost of training employees or others you engage on how to use the system, how to monitor it, and how to retrieve images. Staff turnover can result in this being a significant cost.
Monitoring costs This will include the fees or wages payable for the monitoring of the CCTV cameras, or review of the video data to manage the day-to-day operation of the system, and the compliance and reporting obligations. This could be very expensive.
Publicity costs This will include costs relating to public consultation and community education, including advertising costs.
Evaluation costs This will include the periodic cost of any independent audit of system performance and the formal evaluation of the system’s effectiveness in achieving the crime prevention and community safety objectives.


Careful consideration should be applied to the purchase of ‘proprietary’ CCTV systems, which may commit an organisation into purchasing components or software from a specified supplier or range, possibly making expansion or upgrade difficult in the future.

photoelectric sensor

Tuning the electronic and optical properties of a single layer of black phosphorus by strain force

From the first-principles calculation we can see that the electronic and optical properties of a single layer of black phosphorus strongly depend on the strain released.


Based on the heterogeneous atomic structure of black phosphorus,

Its electronic conductivity and optical reactivity are sensitive to the strain generated

The extent and direction of the.

We have found that the inclusion of many substances plays a necessary role in the formation of a single layer of black phosphorus.

The electronic spacing of unstrained monolayer black phosphorus measured by semi-local function is


Electric volts, while using


Many of the plans

If the effects of matter are taken into account, the electronic spacing will become


Electric volts. The tensile strain is used to reveal a single layer of black

The ability of phosphorus to transfer electrons in the zigzag direction can be significantly enhanced.


Biaxial strain can be used to separate the optical band gap of a single layer of black phosphorus



Electric volt (


Strain force)


Electric volt (


Strain force). The combination of excitons is equally strong

Variable force sensitivity. Research shows that the compressive strain is


Time volts


And the tensile strain is


Time volts


. I

Our calculations confirmed that the optical reaction of black phosphorus is effective under strain.

This is also a promising way to set

A new type of photovoltaic device for obtaining a wide range of solar spectra.



The synthesis of single-layer graphene layers has led to the emergence of a new two-dimensional single-layer material in the field of condensed matter physics. People

It is believed that the synthesis and manufacturing development of single-layer crystallization in the future will pave the way for the exploration of many unique new materials. Now, single

Layer specific graphene layer,

Both transition metal sulfides and boron nitride are readily available, and some nanodevices have been used.


Although single-layer graphite is a magical two-dimensional material, its lack of electron spectral band gap makes people

Look for a band gap ultra-thin material similar to it.

Recently, a single layer of phosphor crystal (also called

Black phosphorus

The successful combination has sparked interest in this material. Single layer stone

The attractive material of the urethane layer can be used in a variety of electronic devices.

Such as a gas sensor,




Solar cell applications, as well as due to its strong bandgap (


Electric volt) and



Compared to having high carrier mobility

Rate-of-effect field effect transistor


). Li et al. used a small layer of black phosphorus crystals and showed good stability at room temperature.

Transistors make field effect transistors (


). In addition, Liu et al. also predicted the stability and structure of single-layer phosphor crystals.

Different characteristics. They observed high current, high field effect hole mobility, and Qualcomm in a few black phosphorus transistors.

Broken ratio.


Et al. confirmed that black phosphorus relies on its traits as a reliable candidate for tunable optoelectronic test applications.

Such as




Field effect transistors require secondary operation in the dark.




Can be fast when illuminated


Rise time reached


Meters per second) perceived broadband index (visible area up to


Nano). Theoretical research on wearing others in the near future

The study shows that the direct energy band gap of black phosphorus is determined by its number of layers (


Electric volts), and its vertical electric field can be used

Tune the bandgap.

Recently, an article has made an accurate and meticulous report on the importance of one to four layers of black phosphorus electronic structures and interlayer jumps.

And people also use density functional theory to study black phosphorus nanobelts.


The electronic structure of a single-layer black phosphorus nanobelt is reported.

And light absorption spectrum. They said that the band gap of the handrail is







The state of the state shown is




Expressed as the width of the nanoribbon. The width dependence of the bandgap depending on the direction is attributed to the electron

Non-relativistic with holes in the zigzag direction, and relativity in the vector direction.



Different electrons and holes have a light absorption spectrum and a different quality but a significant effect.

Han et al. pointed out that the passivated black phosphorus nanobelts

The electronic properties show a strong dependence on direction and strain forces.

Although the electronic and structural properties of single or small black phosphorus have been investigated, the role of strain in these properties

It is still a controversial issue.


Black phosphorus has been studied to have a negative Poisson’s ratio,

And it has a higher mechanical spirit

Activity allows us to use it in the harshest mechanical environments.


Others use density functional theory and combined models,


It shows that the pressure deformation of the crystal plane along the normal direction can change the size of the band gap and also trigger the transition of the semiconductor metal.
Definitions of although
in spite of the fact that; even though.
although the sun was shining it wasn’t that warm
synonyms: in spite of the fact that, despite the fact that, notwithstanding (the fact) that, even though, even if, for all that, while, whilst
Translations of although

n addition,

Fei et al. reported that the anisotropy of free carrier mobility can be controlled by applying biaxial and uniaxial strain.

In the present

In this study we have studied how to change the electronic and optical properties of black phosphorus under biaxial strain.

How to calculate the excitons

Binding energy.

We have compiled the following chapters:

The second chapter introduces the electron and transmission characteristics of black phosphorus under strain force;


The investigation investigated the optical response of monolayer black phosphorus under biaxial strain; the fourth chapter summarizes our research results.


Transmission characteristics

The electron transport volume of a single layer of black phosphorus is


Calculated in the self-consistent non-equilibrium state technology implemented in this

Technology and


Coded connection. double


(added polarization) numerical orbital basis set is used in


In the atomic energy. We are real

The use of modulo conservation in the space grid,


Functional theory and cutoff energy. Electronic transmission is along the armrest side

Calculation of the direction of the zigzag (see figure


). In order to obtain an accurate transmission spectrum, orthogonal to the direction of transmission



The Liyuan area is used as the elastic limit for the period direction.


Grid sampling.


Optical properties

Some people may think that exciton effects are due to weak shielding and low dimensionality


Optical properties. If you want to describe it correctly



Optical properties, many inter-entity effects must be taken into account. For this work, we are



Internal use


Method for calculating a single layer under compression and tensile strain


spectrum. First, the mixture


Calculation use


Fully utilized single layer




The method is carried out. Next is a collision



Calculate the quasi-particle excitons. Finally, we take




High value for obtaining photon adsorption spectra

Including exciton effect


Approximation method.


The calculation method is





On the progress. Wave function and reaction

The energy impairment of the function is





We tried




Empty band collection.

Since the number of empty belts

The amount seriously affects the corresponding position of the quasiparticle energy. Calculate the quasiparticle gap and exciton combination polymerization




The highest used valence and


The lowest unused valence is used as the basis for excitons.



Absorbing a lot of vacuum


We use a vacuum zone at least


To avoid false reactions in periodic images.

=0.05 eV

Complex change

The aggregated spectrum is calculated and expanded.

Table 1 summarizes the calculated electronic gaps for different strain values, optical gap and exciton mixing energy, electron and


The optical properties as a biaxial strain diversity have been plotted in Figure 5. As shown in Table 1 and Figure 5, the use of the mixture is sharp





Single layer


Is calculated as



Consistent with the previous,






Many physical influences


Increase to



Previous theoretical studies are expected to rise or fall under tensile strain or compressive strain

Single layer




. We observed not only






Both are sensitive to application strain. because

So, by tuning the strain,


Optical properties can be easily repaired. in contrast,




It is difficult to change under a single layer

change. Single layer under test


Optical gap is approximately



This with the calculation


Consistent. Last time

During the test, when


Was placed


Surface, shield weakened combination, reduced exciton joint ability, and our simulation

It is also consistent.

Due to low dimensionality and weak shielding, our calculated data predicts a large exciton bound energy value.


This is consistent with our theoretical work. Mention that this calculated exciton binding energy and its single layer

Semiconductor compatible. E.g


Has been found to be a single layer




. Another point is. In the electronic band

When the gap increases rapidly, the tensile strain rises due to the weakening of the insulator shield.


Extended machine bundle


It is worth mentioning that,

When used on one hand


Wave function and eigenvalue as


Calculate input instead of






Instead of




For calculating the importance of quasiparticles and optical gaps.

As mentioned in the previous section, when




Expected single layer


Transition from semiconductor metals. however






Is an indirect band gap semiconductor at strain value


In case. previous

Studies have shown that the calculated vertical compressive strain value is important to reduce the conversion of semiconductor metal under the double layer,







It was found to be bigger. Therefore, to accurately predict the conversion value,


Calculation is the key.

Figure 6 shows a single layer


Optical adsorption spectrum


Have different strain values,

We also showed the use