Challenges in Choosing Surveillance Cameras by John Honovich,
IP Video Market Info posted on May 10, 2009
About John Contact JohnWith hundreds of manufacturers to choose from and little comparative information available, choosing the 'right' surveillance camera can be difficult. Worse yet, specifications provided by manufacturers are often unhelpful or misleading.
In the camera testing I am now performing, here are four fundamental challenges that continue to arise:
How well does the camera work in low light
How well does the camera work in bright sunlight
How much detail does the camera provide
How hard is it to configure the camera for optimal image quality
Handling Low Light
As critical as low light performance is for many security applications, it is as difficult to assess. While numbers are provided, they are not to be trusted. First, everyone measures low light performance slightly differently, making it difficult to compare. Secondly, most manufacturers only include partial information. Third, there is no standard or definition of what an acceptable image is, leaving this up to subjectivity of the manufacturer. All of this results in many manufacturers playing games with these specifications.
If you are trying to assess low light performance, throw these numbers out, do a test yourself in the location you want the camera to be deployed or ask someone you trust what their experience is with the camera. [Note: If you are interested in a comprehensive breakdown on low light performance, see
Axis' note on measuring illumination.]
Dealing with Bright Sunlight
While darkness and sunlight may be opposites, they pose equally difficult challenges for surveillance applications. The problems with sunlight are not limited to outdoors. Anytime you have windows or doors that open to the outside (obviously very common), you are at risk to issues with bright sunlight ruining your surveillance video.
The category of cameras that are designed to address is are Wide Dynamic Range or WDR cameras. However, good luck comparing the specifications of various WDR cameras. Often cameras labeled WDR have no technical specifications and those that do usually measure the range in dBs. However, it's not clear how much better an image is created with a 100 dB range than a 60 dB range. Also, manufacturers may measure this differently.
Seeing Details
Capturing details of a scene are at the core of conducting surveillance. This is critical in determining if your camera meets its security objective and it's also increasingly
important for reducing camera count (by using megapixel).
The stated resolution of a camera is the obvious primary indicator (e.g., Standard Resolution, 1.3MP, 2MP, etc.). However, this is better viewed as the pixel 'potential' than the definite resolution you will obtain.
First, lighting can dramatically reduce the actual details that your camera can produce. To the extent that you have issues with sunlight or darkness (which are very common), your camera will provide details far less than its stated resolution.
Secondly, and this is a special concern for megapixel cameras, not all megapixel cameras, even rated for the same pixel count will deliver the same level of detail.
Determining How Hard Configuration Is
When you see cameras at trade shows or from manufacturer supplied videos, they almost always look outstanding. This happens because:
Manufacturers have technical experts who know all the configuration options of a camera and have significant experience experimenting with various combinations of settings.
Manufacturers know what lighting conditions work best with their cameras and are careful to set up cameras to avoid known areas that expose flaws
If you are integrating or using cameras, you cannot avoid areas that need coverage and you are unlikely to have or want to spend the time becoming an expert at the camera's configurations.
As such, determining how well cameras work 'out of the box' is important. If a camera's image quality can only be made to work well with adjusting multiple settings, the risk of performance problems become high (especially if multiple techs are needed to setup cameras).
Equally critically, be careful in making judgments about camera performance based on manufacturer supplied videos. Like head shots of actors or people's wedding photos, they tend to show an ideal scenario, unlikely to be matched by real world use.
Conclusion
These are some key considerations for choosing surveillance cameras but certainly not the only ones. Other important topics include reliability, bandwidth/storage consumption, information security and more. I look forward to more discussion and debate on these topics.
