Think outside the (black) box
Jul 1, 2000 12:00 PM
Charlie R. Pierce
Even without making a total transition to digital CCTV, there are several black box enhancement tools you can incorporate into your existing system. This article will discuss different ways to automate and/or enhance your CCTV system. The goal is to improve what you have or what you are planning to install. Here are some questions to consider:
n Do I have any privacy issues with surrounding neighbors and is there anything that the digital world has to offer as solutions?
n Can pan/tilt and dome systems be automated to track intruders or is this just another dream of the future?
n Can digital video motion detection systems help to automate my CCTV security?
n Are there any devices available that can enhance video images (both current and/or recorded) to pick up or enlarge small details from a distance?
The four questions above start us on the road to taking our CCTV systems digital.
First, the privacy issues Are you worrying about your private security surveillance systems being used for unauthorized looks into the windows of neighbors, both residential and business? No problem, you say ... We can set the limits on the pan/tilts and domes to prevent the problem at the start. Oh, were it only that easy!
Yes, you can set the limit switches on your pan/tilt and dome systems to prevent wandering off site in many cases. However, in the real world, the effectiveness of this mechanical restriction is usually limited by the overall architecture or layout of your viewing needs. Consequently, setting the stops (either physical or electronic) doesn't always allow your security people the full view of the desired security image. Wouldn't it be wonderful if an electronic device could be added that would blur out certain areas within an image? Something that would continue to block the specified area even as I zoomed in or out and/or panned across the area. Yes it would ... and by the way, welcome to the 21st century. We can now block out areas as small as one pixel or as large as the overall picture.
But you have to look and compare. There is, believe it or not, a fairly large assortment of digital blocking devices entering the market. For the most part, these blocking features are built into the many various digital management systems. However, such built-in blocking systems can sometimes only block out a fixed quadrant of the visual image. If you want to block out an area from view, you might end up having to block out an entire section of the overall image. Although a definite step forward, the cure, in this case, can be worse than the cause.
The good news, however, is that digital image blocking has been developed in the form of a black box addition that is compatible with any format of video imaging (NTSC/PAL). Imagine having an entire office building or apartment complex in full view of your security camera. Now, imagine that the building has 25 individual, private windows within view of your camera(s). Think about being able to block each window of the building out of the picture through blurring without losing sight of the rest of the building or surrounding street. So far so good. But now you need to pan the camera to the right. Will the 25 little blurred images (windows) remain in the new view, causing a checkerboard effect across the screen? Not with digital. The blocking stays with the windows as assigned. When we pan back to the building, we're going to have to reset the window blockage, right? No again. The blockage is still in place. What if we were to zoom in on the building, the blocked areas would remain small, even though the windows grew on the screen, right? Wrong again. As we zoom into or away from the area, the blocked area grows and/or shrinks in direct proportion to the ratio of view area. Is this magic or is this digital? Regardless of your understanding of the electronics involved to make it happen, it is a fairly new feature that can be added to any existing video system and/or planned into your new imaging program. Plan, plan, plan, and think.
Automated operation One of the hardest, and yet most important, aspects you should design into a video system is the capability of hands-free, automated operation. The purpose is to allow the operators to respond to various events instead of having to fiddle around with joy sticks, buttons, screens and/or a host of other distractions. The second advantage of hands-free systems is that the more automated a video system, the less likely you are to miss potentially important information. And the last purpose of hands free design is to promote personal interaction without the playing around that can happen with most systems. Obviously, alarm interface is a good way to achieve our needs here. We can use door contacts, card readers, photo beams, and other such devices to activate video images from specific cameras and/or to sound bells, to start recorders, etc. It is an extremely viable form of automating a video system to insure coverage that could go unnoticed.
Let's take a look at one of the more demanding aspects of your design: the pan/tilt or dome arrangement. Without much effort, any system can be designed to provide various, useful options. Pre-positioning allows us to program-in visual tours of specified areas either through timing sequences or alarm interface. In addition, we are able to set up our systems automatically to move from camera to camera and from scene to scene. But what about the more demanding features of the pan/tilt or dome? What if a scene is pulled up, and the security person needs to follow someone or something from point to point using the pan/tilt or dome? We are now faced with a hands-on problem. If the security person does not pay careful attention, interacting with zoom and pan/tilt functions, it is very possible that he will lose the object being observed. It is equally possible that he could miss an opportune piece of evidence. Consequently, the ability to respond fully to the situation by calling for help, directing response teams, and/or other needs are hampered by the need for personal interaction with the control system. So, what can we do? What about a system that automatically views a predetermined area, detects action, annunciates such action according to a planned event sequence (kicks in the recorders, brings up the image on a screen, sounds bells) and automatically controls the pan/ tilt, dome and zoom lens to track the object through the area of view? How about if that same system could "pass" or "hand" the object of concern over to an adjacent camera as the object moves out of the initial camera viewing area? What if the same system would allow the initial camera to automatically reset itself to its original programming parameters after it passed the image off? Yes, the digital revolution is enabling us to automate our video tracking systems.
Digital video motion detection When it comes to being versatile, digital video motion detection (DVM) takes the lead in alarm/video interface. There are no running wires to remote areas, no heavy labor requirements and no compatibility problems among multiple systems. On the other hand, DVM used outdoors is said to be a prelude to multiple false alarms. Is it true? Not really.
In simple terms, the DVM unit is looking for contrast change within a video image. If an area or object being observed changes from bright to dark, or vice versa, the DVM detects the change and responds according to set parameters. For years, the only real control we had over video motion detection was the sensitivity (amount of contrast change) and the general area of concentration or concern. With the introduction of digital, some 20 years ago, we opened the door to a wonderful world of options. Now, not only can we detect change of contrast and adjust the sensitivity of that change, we can narrow it down to a single-pixel point of detection. We can cover multiple, individual points within a single area. We can determine the direction of movement and set alarm parameters accordingly. If we only want an alarm condition if someone or something moves toward a building, we can preset it. We can preset the size of the object of alarm, allowing us to distinguish between a truck or a man moving through the image. We can monitor the overall image to buffer against false alarms caused by clouds passing in front of the sun or headlights sweeping by. We can create three-dimensional blocks of space around specific objects, allowing for people to pass in front of, over, under or behind them without creating an alarm.
Not all DVM devices are created equal. Several different devices now have some sort of DVM function built-in. However, the DVM function in some of them acts to enhance sales as much as an actual working feature. For what they are designed to do - inside areas only - they work very well. They do not carry all of the features of a true digital video motion detection unit. Unfortunately, many people in the CCTV arena think the built-in DVMs are as good as it gets. Consequently, most CCTV system designers avoid and/or limit their video motion interface options to simple indoor applications, i.e., "let me know if someone walks by." The strength of a good DVM system is its ability to monitor large, outdoor areas.
With a good DVM system, we can program several functions to coincide with our security parameters. These functions include:
n size of detectable intruder
n direction of motion of intruder
n amount of image change or sensitivity
n specific areas of detection (as large as a field or as small as a mouse)
n scene change comparisons for cloud or headlight interference and more.
Besides the obvious advantages, responses to alarms can be minimized because of the immediate view of the area in suspect. Bottom line ... applying a true DVM unit to your system offers area protection that has never before been so accurate, easy to set up, and quick to respond.
Enhancing video images When using a camera system, you may need to obtain specific information, such as a license plate number, out of an image that isn't necessarily immediately clear. The first and most important question that comes to mind: Can it be done? The answer, thanks to digital technology, is yes! Again, new to the CCTV industry and thanks to the individual pixel-point quality of digitizing the video image, we can now feed a live or recorded image into complex, black box technology and obtain remarkable results enhancing the image.
Look at that license plate on that car parked three blocks away ... it is not large enough to read. Blowing up the image alone merely spreads the pixels apart. What do you do? Feed the image through a video enhancement tool and, voila! The image is blown up, the pixels are averaged out, and we have a readable license plate, or perhaps a recognizable face. Would enhanced video information retain its value in a courtroom? Most likely, yes. The image has been digitally enhanced, but it has not been altered. The available information has merely been better defined. Would it be a valuable tool to make available to your security staff? I don't know. It depends entirely upon your overall application and purpose of your video system. Is the device something you would build-in as an everyday device to provide a better perspective on all of your images? No, probably not. It's not for everyone.
>From the perspective of add-on or black box enhancement technologies, >there is a potentially huge box of digital toys and tools. I have only >begun to list the potentials and realities. There's much more to come. The >whole process of going digital relates to planning, thinking, >investigating, testing, proving, and then doing. So far, we have made some >pretty good progress on the first stage.