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Video Cameras
(Chapter 2   Video Surveillance, Continued)

Color versus black-and-white cameras

In a high-security application, when an alarm has been generated signaling a presence in an off-limits area, it is likely to be sufficient to be able to assess the alarm condition with a black-and-white camera. The objective here is merely to determine that it is a person intruding (any person) and that a response should be prepared or dispatched.

In a school application, the security objective of recording video scenes would generally be to determine who the perpetrator of an incident was. In this type of after-the-fact assessment, it is most important to identify, not just detect, the intruder. Because of this, color cameras are probably more helpful for most school applications than black-and-white cameras. Color recordings will contain much more information about the scene that was viewed, i.e., the boy who broke the window had red hair, a dark yellow jacket, and drove away in a light blue car. This can be critical for school applications; the school principal can match the characteristics of the recorded suspect with those of students or outsiders known to frequent the area. Quite often, when a suspected student is brought in and shown a recording of himself or herself in an incident, he or she will admit to a role in it, even though there may not have been quite enough detail on tape for a positive identification.

Color cameras usually have lower resolution than black-and-white cameras. However, for the school application, the ability to recognize the color of clothing, color of vehicle, and so forth is often more important than a more detailed image. The amount of information on a video recording that is required to prosecute a suspect in a court of law may be much greater in many instances than what a school video system will normally collect.

The cost of color cameras is slowly approaching the cost of black-and-white cameras. Currently, the cost of a color camera as compared to an equivalent black-and-white camera is anywhere from 30 percent to 70 percent greater. Most school applications will find the higher priced color cameras necessary for their goals. An exception to this would be a camera applied in a small interior room or area where any potential perpetrators will be close enough so that their faces will be easily identifiable in black and white.

When using either black-and-white or color cameras under low light level conditions (such as at night with artificial lighting) it is necessary to evaluate the effectiveness of the existing lighting. Generally, security applications of cameras require higher light levels and more evenly distributed lighting than is found in parking lots with typical safety lighting. Also, if school officials plan to use their cameras for nighttime applications, color cameras will require a higher lighting level than black and white cameras. (See the section on lighting requirements and nighttime applications.)

 



Research Report:   The Appropriate and Effective Use of Security Technologies in U.S. Schools