Professional CCTV surveillance systems available today offer features that provide users with a level of safety and security undreamed of 25 years ago, even though developments in the previous 25 years (since CCTV originated) were still remarkable in their own right.
Digital technology, which became truly available in the 1980s, has a great deal to do with the sophistication of present-day CCTV systems. However, the question still arises - is there a limit to how far technology can be further developed and applied to achieve ultimate - that is, near-perfect - security?
This article highlights the progress so far achieved to reach the present status quo, and 'focuses' on the importance of the camera in the imaging chain. In addition, we give an overview, from an industry point of view, of what is available today and what may yet be feasible within the foreseeable future to enable CCTV surveillance systems to offer their users the elusive ultimate of 'seeing all and knowing all'.
The 'all-seeing eye'?
Logically, the place to start is where the CCTV chain begins - the 'eye' of the system - the camera - because the quality of the image viewed greatly depends on the type and quality of the camera(s) used. However, it is important to remember that a video camera is not the same as the human eye. While the human (stereoscopic) eye presents a three-dimensional image to the brain, the camera only produces a flat, two-dimensional image that uses shades and colour hues to give the illusion of depth. Position and height of the camera also add to the illusion of depth and distance, but cannot truly give the same effect. Moreover, the human eye automatically compensates for variations of light and shadow - something that analog cameras could not do. Fortunately, as with broadcast and still cameras, advances in lens technology have brought to CCTV significant improvements in resolution and sensitivity, aided by two marvels of digital technology, the charged-couple device (CCD) and digital signal processing (DSP).
The types of camera available today and their many features are most impressive, developed from both the demand generated by the growing number of different applications and the ingenuity of the manufacturers. From compact, fixed cameras, through direction-controllable models to high-end, sophisticated 'intelligent' cameras that capture the entire dynamic range of a scene regardless of the light conditions. Other features, many of which are enabled by digital technology, further enhance the functionality of cameras, such as miniaturisation, motion detection, day/night operation, backlight compensation, dynamic noise reduction, remote and automatic lens control and numerous others. A wide range of accessories provides choice of mounting, weatherproofing, and tamper, impact and hazardous substance resistance.
As with cameras, a wide range of connectivity, viewing, recording and storage, and control products is currently available to complete the CCTV chain, also strongly impacted by digital technology and a steady decrease in prices over time. Solutions are now available that ensure optimal, end-to-end interconnection over virtually any distance (with cable length compensation), including the use of Internet and intranet techniques (see below). Secondly, today's state-of-the art CRT and compact, flat-screen monitors provide high-resolution, multi-image, multiscreen displays that allow observers to view images with maximum visual information. Thirdly, DVRs have been developed that employ new compression techniques based on the MPEG-4 standard and with hard disk drive capacities of up to 600 gigabyte, enough for 10 weeks of recording at a frame rate of six inches per second. Such DVRs also provide tamper-proof storage that answers the (legal) need for preventing the editing of images without being detected. And lastly, control (direct and remote), image storage, and retrieval and analysis hardware and software help complete typical, large-scale CCTV systems currently available from major manufacturers.
The advantages of IP-based surveillance installations over conventional DVR CCTV systems are many. At the camera level, the scalability of an IP-based system is from a single camera to thousands in increments of one, compared to 16-camera/channel steps for DVR. Also, frame rate (any camera can be provided with any frame rate at any time) and storage capacity can be increased simply by adding hard drives and PC servers. Plus, in most cases, an organisation's existing LAN, Internet or intranet two-wire infrastructure can be used - where such an infrastructure is not available, at least providing new two-wire cabling would cost a lot less than coax. Add to this: intelligent functionality at camera level, such as motion detection, sensor input, relay output and alarm triggering; faster systems integration allowing one network that controls audio, video and data; remote accessibility of live or stored video streams from any location, and increased reliability through realtime management software.
Instead of a DVR, IP-based security systems usually employ a networked video recorder (NVR) - an 'intelligent' video server that enables much of the functionality described above. In addition to video, an NVR can also record audio; it can record from any camera in the system and play back to any monitor. It is the key enabler of LAN or IP-based networked installations, which are rapidly becoming the systems of choice for large and/or remote applications requiring maximum flexibility with optimal price/performance.
Foremost among issues that existing and potential users are concerned about are camera resolution and sensitivity. Obviously, the better a camera can perform in these terms, as well as its imaging and control flexibility, and the choice of models available from a particular vendor, the better the chance that that brand will be chosen. Other issues affecting choice of vendor include total product/system program, product price/performance and ease of installation ('plug-and-play'), proven track record (including product innovation), reliability, capability of delivering seamless transition from analog to digital, quality and accessibility of customer service, and warranty conditions.
The table below is a simplified overview of criteria that determine the choice of a CCTV system and its configuration.
Without doubt, IP is the area showing most promise for the further development of surveillance systems and, indeed, new applications. This implies that digital is the only way forward and that there is no place in the future for analog technology. However, some analog elements of CCTV systems will still be in demand for relatively small systems for some time, including a combination of analog and digital. Although we would not like to predict what that time scale is, it is fairly certain that, in the longer term, digital will be the only technology of choice.
We see new applications emerging, such as school surveillance (unfortunately triggered by recent fatal violence incidents in the USA and other countries), vehicle licence plate recognition, eg detecting a stolen car, and suspect criminal identification. Such applications call for new and innovative features and intelligent functionality in both CCTV hardware and software. These include advanced video motion detection; higher levels of image resolution to further improve image quality; wider use of wireless transmission, particularly in LAN and IP-based networks; and sophisticated encryption techniques like watermarking for digital rights management (DRM) of video, similar to that employed in the protection of broadcast content. It is equally certain that enterprising surveillance system manufacturers, hand-in-hand with project engineers, system architects, builders, consultants and town and city planners, will find yet more interesting applications and provide the CCTV solutions to realise them. And thus achieve yet another step towards near-perfect security: 'seeing all, and knowing all'.
Ad Biemans is product marketing manager CCTV at Bosch Security Systems, Eindhoven, The Netherlands.
© Technews Publishing (Pty) Ltd | All Rights Reserved