Camera Resolution refers to the number of pixels that are captured within a digital image. It's pretty much a rule of thumb when picking digital still cameras that the more megapixels you have the better the camera. And it is true, when regarding a "still" photograph - the more pixels available equal more data which equals a higher resolution and higher quality image. With regard to security cameras this same rule of thumb is true to point . The quality of your image can be effected - and even downgraded - by the type of area you are monitoring with your security camera. Consider the following picture.
We've broken the image up into 5 sections to illustrate in a simple manner what pixels are active in a representative image for a 5M camera. If you consider each vertical bar 1 megapixel of data, then you can see what happens when that data is extracted. In #1, we can see the name of the hotel. In #2 we can see people but you can not distinguish facial characteristics. The number of pixels involved in making up picture #1 and #2 are less than 100k at most - a far cry from a 5M camera image.
This is no better than blowing up a standard CCTV camera image. If this same camera was set up in a showroom or a meeting room - where the subjects would be 30-feet from the camera or less, for instance - the usable portion of the picture would be far higher. Details of dress, individual behavior, motion, identifying marks would become readily apparent. That is the environment where a high megapixel camera can shine. You could of course do the same job with multiple standard CCTV cameras, but would see little improvement in image quality.
Some customers purchasing IP Network cameras will have the mistaken impression they can place high megapixel cameras in positions to overlook a large area (like a parking lot or a field) and save money by making it the sole camera in the area. Those customers are often disappointed when an incident occurs and they have to blow up the image to identify a suspect - they don't get the 5M image they expected and get a person with a blob for a face. The money they spent on a high megapixel camera might have purchased a number of standard (traditional analog) CCTV cameras with varifocal lenses in an overlapping array, which likely would provide a very usable, crisp, high quality image when they need it.