Video Recording systems are in the midst of rapid technical change and improvement. In particular the market is shifting from analog to digital recording platforms. Each of these systems have their own advantages and disadvantages, but not unlike VCR's and even film cameras, analog systems will eventually become obsolete.
As an integrator there are several factors we must consider to make any system work to its maximum possible potential. These factors include: Capturing the Full Image, Lighting, Data Flow Management, and Image Appearance.
To capture the full image both the field of view and the depth of view must be carefully considered. Camera position, the number of cameras, the camera's aspect ratio, and finally the lens choice will all determine if the desired image will be recorded while maintaining the appropriate detail needed for the subject.
Lighting is one of the most critical factors in determining the quality of the recorded image. The unit of measurement to determine the amount of light in an area is called a LUX. Every camera has a full color LUX rating, a black and white LUX rating, a range of light it can properly record in one picture, and a range of light it can record from picture to picture. Camera choice must be based on the worst lighting conditions that the camera may encounter. Low light, limits color fidelity and resolution regardless of the camera being used.
In scenarios were lighting is poor and/or cannot be corrected special cameras will be necessary. Some functions of these special cameras are: built-in infrared lights, Wide Dynamic Range technology, Super Wide Dynamic Range technology, as well as other various software based picture enhancement technologies.
Data flow management is more important than ever. All video is compressed to allow the most picture information to be transmitted and stored. This information is sent over some type of transmission path, such as Coaxial or CAT5 cable. This path has a limited bandwidth, so only a certain amount of information can be sent at a time. The quality of the video that can be transmitted is often constrained by bandwidth of its path. As video is compressed it requires less bandwidth, but picture quality is also reduced. The further video is compressed the more you can store in a given device, such as a DVR or NVR.
Resolution is the key to a good image appearance. Resolution is the number of pixels used to create a single image and is usually measured by multiplying the number of vertical pixels by the number of horizontal pixels. As the number of pixels increase so does the resolution and the image clarity, but the improved resolution comes at a cost. The higher the resolution the more data is required per picture which increases the amount of storage space and the amount of bandwidth required. A precise balance between image quality and image size must be maintained.
Currently there are many resolutions for CCTV including: High Definition (1080), High Definition (720), Standard Definition, High Resolution, and Standard Resolution. See the charts below for examples.
|High Definition (1080)||1920x1080 (approx. 2.07 MP)||16:9||HDTV 1080||Digital|
|High Definition (720)||1280x720 (approx. 0.92 MP)||16:9||HDTV 720||Digital|
|Standard Definition||720x540 (approx. 0.39 MP)||4:3||SDTV||Analog|
|High Resolution||approx. 540x405 or 0.22 MP||4:3||540 TVL||Analog|
|Standard Resolution||approx. 380x285 or 0.11 MP||4:3||380 TVL||Analog|