Video Surveillance: One Resolution Does Not Fit All

Let the user's needs be your ultimate guide

What makes a surveillance system successful? You can talk about return on investment or crime reduction statistics, but really, the true success factor is the delivery of imagery that is actionable. Simply put, surveillance video is only valuable if it can actually be used.

Before designing or installing a video surveillance system, it is important to determine what the customer’s needs and expectations are, so in turn the proper cameras are selected. Typically this goal-setting question is answered by one or more of the following operational requirements: detection, recognition and identification.

Being an integrator in the security market is not easy; just think about the hundreds of booths at ISC West all showing the “best” video surveillance solution. Or think of all the hype about the latest and greatest high resolution technology. With the sheer volume of products available, selecting the right camera can be like finding a needle in a haystack. Determining the operational requirements of the solution will help narrow down the haystack so you can find the needle—or in this case, the ideal video surveillance solution—for your customer.

What does your customer really need?

First you must know your customer and what they are trying to accomplish. Does the customer want to identify the person entering a restricted area or simply know an intrusion occurred? The number of “pixels on target” needed to satisfy the operational requirement can be used to shrink the haystack when selecting products.

The three common operational requirements – detection, recognition and identification – each have a corresponding pixel requirement that refers to the minimum pixel density of an object or person. Though there is no industry standard for pixel density requirements, there are references and guidelines from various organizations, including the Swedish National Laboratory of Forensic Science (SKL) reference used for this article.

As you would expect, the most demanding requirement is identification with 12.5 pixels needed per inch or 80 pixels across a person’s face, while detection and recognition come in at 0.5 px/in and 2.5 px/in, respectively. If you install more cameras, you will better meet the pixel density requirements and provide more coverage, right? Often with the proper combination of camera selection, lens pairing and installation location, you can actually cover more with less.

In fact, in most cases a standard definition camera paired with the appropriate lens and camera placement will meet customer requirements. However, standard resolution cameras require either a sacrifice in detail by setting a wide field of view or situational awareness by narrowing it. To deliver both, security practitioners can deploy higher resolution cameras.

The evolution of resolution

This raises the question: HDTV or megapixel? First, it’s important to understand the difference between these two technologies and how each came to be prominent in the security industry.

In the early- to mid-2000s, rapid development in resolution saturated the point-and-shoot digital camera market with inexpensive megapixel models. The most popular camera sellers went from 1MP to 8MP and even up to 12 MP. More was better and further growth was only limited by the lens.

Then something interesting happened: the original iPhone launched in 2007 with a 2MP camera, and the trend of “more megapixels” reversed. Sales were instead dominated by the 2 to 5MP camera phone.

Meanwhile, HDTV came in to the picture with the broadcast of professional sports games about the same time. Within a few short years, it was clear that analog was dead and 720p/1080p HDTV were the preferred new formats among consumers.

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