Core CCTV Chicago & Video Surveillance System Chicago Components


Video Surveillance Systems Chicago Components:
This section provides a summary of the fundamental components of a video system. These
components provide the foundation for any basic video system. Each component affects video quality. The user can use the Generalized Use Class that he created based on the selections from Table I to identify performance specifications for the video system components in future guidance material. This section provides qualitative information that will help the reader develop
qualitative requirements for system components. Future guidance material will provide detailed specifications and additional considerations for selecting Video Surveillance Systems Chicago Components | CCTV Systems Chicago.

A. Lens Configuration
The optical component of a camera system is a lens or series of lenses used to create an image on some
sort of media, such as photographic film or electronic means. A lens can be a simple convex surface or
composed of a number of optical elements in order to correct the many optical aberrations that arise. A
lens may be permanently fixed to a camera or may be interchangeable with lenses of
different focal lengths, apertures, and other properties.

Attributes that might affect video qualityof Video Surveillance Systems Chicago Components | CCTV Systems Chicago.
• Lens Aberration – Lenses do not form perfect images; there is always some degree of distortion
or aberration introduced by the lens which causes the image to be an imperfect replica of the
• Field of View* – Extent of the observable world that is seen at any given moment through the
• Focal Length* – Determines the field of view, and the apparent size of the objects relative to the
image size.
• Aperture* – Relates to lens opening to reduce or increase light that reaches the image capture
surface. Controls the brightness of the image and the fastest shutter speed usable.
• Depth of Field* – The range of distances that appear acceptably sharp in the image.

B. Image Capture
Image capture is the process of recording data, such as an image or video sequence.
The Image Capture process consists of converting the information (i.e., light) from a real scene into a
stream of information that is suitable for the remaining links, via a photographic or electronic medium.
In the case of modern video, the chain is modified slightly. The camera is in front of a scene and it has
optics (usually just a lens, but it could be a night-vision system). The lens presents focused light to the
internal workings of the camera—a projection of the information from the scene. The camera converts
the projected information into a stream of electronic data that can support subsequent processing,
storage, and viewing. For digital images, the capture process converts light into a digital form via a
sensor and digitization.
Attributes that might affect video quality of Video Surveillance Systems Chicago Components | CCTV Systems Chicago
• Resolution at which it captures
• Frame rate at which it captures
• Fidelity of the colors used
• Dynamic range of the recording medium
• Number of bits per pixel (digital cameras)
• Noise (analog cameras)
• Infrared capability of image capture system

C. Processing
Processing refers to any enhancement, restoration, or other operation that is performed on a video
signal. This could also refer to any processing that occurs automatically as part of a system; for example,

Attributes that might affect video quality of Video Surveillance Systems Chicago Components | CCTV Systems Chicago
• Compression – Also referred to as coding, compression involves electronically processing a
digital video picture so that it uses less storage and allows more video to be sent through a
transmission channel. Most methods for compression result in a loss of fidelity that is not
recoverable. Compression can be used to reduce the amount of bandwidth needed to transmit
a video. A user must use a decoder to view a file that has been compressed (or encoded) or else
the video cannot be viewed. There are open-source video encoder/decoders that exist on the
market; however there are many proprietary systems that require their own specific decoder.
• Digitization – Converting an analog video source to a digital format.
• Enhancement for analysis – Many methods are available to increase clarity to certain parts of
the video. Examples are frame averaging, edge enhancement, and color balancing.
• Delay – Video images can be delayed which can result in incomplete or inaccurate real-time

D. Transport
Transport refers to the effects of moving or copying from one location to another.
Transport and Network are terms that go hand-in-hand, depending on the Information Technology
Engineer preference. This document will refer to it as transport. The transport can be wired (including
fiber optics) or wireless, or any combination of these. The distance of the transport can range from a
few feet within a building, to the other side of the world, or into outer space. The transport has
unpredictable effects on the transmission of the electrical signal between two or more electronic
Attributes that might affect video quality of Video Surveillance Systems Chicago Components | CCTV Systems Chicago
• Available bandwidth – How much data a network is able to carry affects the speed and size of
the video signal that is able to reach the destination.
• Network sharing – Other users on the network may reduce the available bandwidth.
• Loss of data (digital)* – When digital information is transmitted; it is broken into short blocks of
data called packets. Packets are sent separately and then reassembled on the receiving end of
the system. For many reasons some packets are lost in transmission, causing a loss of some
pieces of the video picture.
• Loss of data (analog)* – Noise can interfere with an analog signal (e.g., “snow” on analog TV),
permanently obscuring portions of the video field.
• Delay – Video images can be delayed which can result in incomplete or inaccurate real-time

E. Storage
Video can be used for real-time (e.g., monitoring or tactical) applications or stored for future analysis.
Improperly stored video may be unusable due to loss or degradation of data, for example improper
storage of video would be a critical issue in evidentiary and forensic video applications. Video must be
stored simultaneously at a high bit rate and low bit rate to prevent irretrievable data loss. For example,
some systems may provide a low bit rate stream for wireless monitoring while simultaneously storing a
higher bit rate version locally.
In order to decrease the bit rate, storage is also often preceded by some form of processing. File format
can be altered to fit different media, such as coding the video in MPEG 2 for storage on a DVD and
playback with a DVD player. A series of alterations or physical custody changes made to a video file is
called the “storage chain.” The storage chain should be monitored and documented very closely since
almost every change in file format results in a loss of data.

F. Display
To present a true quality picture of video footage captured, the emergency response community
depends on a good quality image display unit to aid in accurately communicating information to the end
Emergency medical services increasingly use display in medical diagnosis, in firefighting for research and
training, and in law enforcement for evidence in the courtroom. Selecting the proper display for the end
user’s specific video applications can be as important to achieving the user’s goal for the video footage,
as selecting the appropriate camera equipment.
Attributes that might affect video quality of Video Surveillance Systems Chicago Components | CCTV Systems Chicago
• “Trueness” of the colors displayed
• Aspect ratio used


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