Video cameras are being installed in many new applications. Nanny-cams, police and home security networks, traffic jam monitors, and small-business webcams are just a few of the video monitoring devices employed by and for the average American.
A report from “Research and Markets” says that the global closed circuit television (CCTV) market grew at a Compound Annual Growth Rate (CAGR) of 24.3% in 2007 and is forecast to grow at a CAGR of approximately 23% from 2008 to 2012.
Systems are available for the “do-it-yourself” type. Systems that can be installed with wireless transmission of the video signal helps in this regard. More sophisticated systems may require the utilization of a professional installation.
There are three types of CCTV technologies. The oldest technology units are analog systems. These systems have the lowest cost for the hardware, and are useful for some services.
The second type of CCTV is called hybrid technology. These systems capture the image with analog cameras, and convert the signals to digital format, which can be more economical if it is necessary to retain long periods of video. By digitizing the data, software manipulation of the image becomes possible.
The newest player in security cameras is the IP camera. This camera technology can be implemented anywhere where a computer network is available. Because the interface cables may be avoided, this solution can result in the lowest cost and quickest installation. This type of interface is also best when the distance between camera and host is significant.
Night vision cameras are becoming more common. There are two types of night vision cameras: those that can capture an image with little light, and those that have infrared lamps (most often IR LEDs). The distance that can be seen by an IR camera is proportionate to the output of IR light. While in infrared mode, an infrared camera will record only in black and white, but there are cameras available that can monitor with color during daylight hours. Sensors on the camera automatically switch from color recording to black and white according to the light level. Avoid using an infrared camera that is contained in a glass or acrylic front outdoor housing. Infrared light will reflect off the housing, creating glare that obscures the image.
Data storage is always a significant problem with CCTV. Video surveillance systems can be memory hogs (For example, video with resolution of 640 x 480 at 30 frames per second and I420 pixel format requires 640 x 480 x 30 x 1.5 = 13 MB data per second). For this reason, most systems include signal compression to reduce the required capacity. Even with signal compression, it will be necessary to decide on the period of data retention, and sample rate.
Video analytics is the technology of applying software techniques to the interpretation of the video image, so that a computer can filter the data, and call attention to a human operator if necessary. It is important to understand the current limitations of this technology. One should not expect that a CCTV system incorporating video analytics will replicate human perception. Video images of busy environments can be very difficult to interpret for a computer, but images that are more static can be more successfully measured. What video analytics can do is act as a “force multiplier”, allowing a single human to effectively monitor many cameras.