Round the clock surveillance
Security Middle East looks at how camera manufacturers are using technology innovations to deliver improved night-time images
The need for good quality image capture in low light conditions is widely agreed. These days most CCTV system designers will tell you that if image quality falls away each evening at sunset then the money you´ve spent on the system is wasted. Your surveillance system, after all, is only as good as its weakest pictures.
The fact is that today the tools exist to achieve good images both day and night. Camera manufacturers have focused on improving the ability of their units to capture and process images, regardless of the light available. This means that the system designer can get away with using ambient lighting more often, without suffering from the same image degradation – and of course when they use dedicated lighting as well, they can see further and better.
Noise reduction techniques
Samsung is a good example of a company that has made low light capture a standard feature across its whole range. The company´s SSNR (Super Noise Reduction) technology is now on its third generation and is a core technology used in all its chip sets. Noise in CCTV images is one of the most common causes of video material being considered as unreliable evidence.
This is particularly so in low light environments, although not exclusively, as noise can be generated in all lighting conditions. Noise occurs when AGC (Automatic Gain Control) attempts to compensate for a weak video signal. The resulting graininess and snow-type effects can render an image unusable before the actual darkness does. If, therefore, the noise can be removed, the image would still be usable. This is the thinking behind the development of noise reduction technology which makes images cleaner and sharper by eliminating the high levels of noise without creating ghosting or motion blur.
In tests, colour images with noise reduction technology applied, stay sharp and clean, even after colour information is lost due to a lack of light. The technology is arguably more impressive when the camera is in monochrome mode.
If a CCTV system is surveying an area where crisp, clean and detailed images are required in all types of illumination, cameras with noise reduction technology can solve many problems that standard cameras will struggle to overcome.
Because the processing increases the signal to noise ratio and considers both random and predictable sources of noise, this even means that streaking from vehicle lights in motion can be eliminated.
Samsung´s latest version features ´pattern matching´ which also maintains the object´s edges in both static and moving images. After removing the noise, a very small 3 x 3 matrix matching system is employed to ensure the scene produced by the camera is as close as possible to the original image.
The trade price of these cameras has come right down, although you still have to pay more if you want features such as analytics,(optical trip wire, subject tracking, VMD etc, a wider dynamic range (balancing the whole image, with light and dark areas evened out), virtual progressive scan (to sharpen moving objects when a recording is paused), and polygonal privacy zones. These are all features of higher end cameras.
HDTV domes with ´gatekeeper´ feature
Axis Communications has recently introduced a series of highperformance, outdoor-ready PTZ domes, including two HDTV models, for more demanding surveillance applications – all three have automatic day and night functionality, enabling good image quality round the clock. These cameras are designed to provide HDTV coverage of large areas with great detail when zooming in.
The PTZ cameras provide H.264 video compression format, which optimises bandwidth and storage use without compromising image quality. Motion JPEG is also supported for increased flexibility. Intelligent features offered by the series include the ´advanced gatekeeper´ functionality, which enables the cameras to automatically pan, tilt and zoom in to a pre-set position when motion is detected in a pre-defined area and return to the home position after a set time.
AXIS Q6034-E´s Active Gatekeeper offers a similar function, but with the added ability to follow the detected object. The auto-tracking feature in AXIS Q6034-E can also be used as an alarm trigger.
CBC´s ZC-NH250P camera´s increased sensitivity requires illumination of only 0.04 lux
High resolution internal and external
Suitable for internal and external applications, CBC´s ZC-NH250P camera is a super high resolution, true day/night, compact box camera that provides optimised sensitivity in both day and night-time conditions. As the illumination of the viewed scene reduces, an IR cut filter is automatically removed and the camera switches to black and white mode.
With its increased sensitivity it then requires illumination of only 0.04 lux. A high performance CCD image sensor combined with an advanced digital signal processing chip delivers high resolution, 540TVL colour pictures during the day and sharp black and white pictures at night.
The camera is versatile when it comes to lens selection, allowing the use of DC or Video drive automatic iris lenses and even manual iris lenses via an automatic electronic shutter (AES) setting. This is where the CCD photo sensors exposure time is automatically adjusted and controlled by referencing the level of illumination in the scene.
Other features included in the camera are: internal or line lock
synchronisation complete with phase adjustment, automatic gain control, auto white balance correction and back-light compensation.
Meanwhile, another new option from CBC is the super high
resolution ZC-NH405P which features 10-bit digital signal processing technology, delivering very high quality pictures.
Electronic enhancement
Panasonic´s WV-CL924A combines a near-infrared CCD with a new digital signal processor. Switching automatically from colour mode during the day to B/W mode at night, these cameras are aimed at a wide range of 24-hour surveillance applications. When equipped with an F1.4 lens, they deliver clear images in light as low as 0.14 lx in colour mode and as low as 0.01 lx in B/W mode.
With electronic enhancement, sensitivity is up to 32 times greater than that of standard cameras. When combined with a near-infrared light source, these cameras can also be used for near-infrared (B/W) surveillance in covert settings with no visible light. The horizontal resolution is 480 lines in colour mode, and 570 lines in black and white.
Features with this model include a high-speed electronic shutter,
character display, and an alarm output terminal for use with remote
sensors or other surveillance equipment.
Improved sensitivity
Sony´s SSC-E438P incorporates a 1/3-type Super HAD CCD II, which offers highly improved sensitivity compared to the conventional Super HAD CCD. It is designed for surveillance applications in retail outlets, offices, banks etc. The camera provides a minimum illumination of 0.4 lx at F1.2 in colour mode and 0.05 lx at F1.2 in B/W mode.
Unlike conventional digital signal processing, the DSP mployed in this camera increases the horizontal resolution attainable by the CCD. The combination of this DSP technology and the Super HAD CCD II technology enables the camera to offer a high horizontal resolution of 540 TV lines, providing clear and detailed images.
Meanwhile the ATW feature automatically adjusts the camera´s white balance to adopt to changing light conditions. The SSC-E438P provides a very wide ATW range of 2,000 K to 10,000 K, allowing adjustment-free operation under a variety of light conditions.
Crisp, aperture-corrected images
Finally, from Siemens, the CCWC1335 is a high resolution wide dynamic day-night camera that uses the latest CCD technology and advanced digital signal processing techniques to provide crisp, aperture corrected images.
The use of wide dynamic technology ensures clear viewing in any bright back-lit scenes and a mechanical infrared cut filter ensures crisp aperture corrected, low-smear images 24 hours a day. In night mode the camera is infrared-sensitive and should be used with infrared illumination and day-night lenses to ensure there is no focus shift.
Other features include digital zoom, OSD with 6 zone programmable back-light compensation, camera titles, slow shutter speed to x320, digital zoom and eight privacy zones.