Select any medium to high spec camera and, for daylight applications, you are unlikely to have any problems. The specification and performance of cameras available from many of the world’s reputable CCTV manufacturers are now so good that even inexperienced installers, who may not fully understand the importance of correct camera setup, can keep out of trouble.
Night time or low light applications are, however, not quite so forgiving if the camera selected is not fit for purpose.
Samsung Techwin were among the first CCTV manufacturers to recognise that, as customers’ expectations for CCTV rose, there would be an increase in demand for cameras that could perform well in low light situations. Our Super Noise Reduction technology (SSNR) was developed with this in mind.
The projects and applications where cameras may be expected to perform well in low light camera conditions are, of course, many and varied. On these pages we take a look at three Samsung Techwin cameras and the solutions they offer …
SDN-500
A colour/mono camera with a difference! The SDN-500 is a 1/3 inch High Resolution camera giving crisp, noise-free colour images in light levels as low as 0.28 lux thanks to the in-built SSNR technology. Colour/Mono cameras can compromise on daytime colour images due to the lack of a removable IR cut-filter, but the SDN-500 has overcome this problem with advanced circuitry.
Typical Applications: Industrial/commercial sites where the CCTV system is required to record evidential quality images of site activity during the day and detect and record intruders at night with good ambient light levels such as street lighting or better.
SDN-520
A true Day/Night camera designed to give best quality colour images during the day, thanks to an automatic removable IR cut-filter, switching to monochrome images for clearer pictures when the light falls to a certain level. The SDN-520 has excellent sensitivity down to .5 lux (dusk) for colour and .03 lux for monochrome. It also has an excellent spectral response range and is, therefore, ideal for use with IR lamps,
Typical Applications: High security applications such as airports, military or high-tech establishments where ambient lighting levels are consistently good … or anywhere where ambient lighting at night is so poor that IR must be used. Also, anywhere where identification as well as verification of an intruder is important.
SHC-721A
A Low light camera to suit any 24-hour surveillance requirement, the SHC-721A boasts a host of features for individual or varied lighting conditions.
Combining the strengths of the 500 and the 520, it is a true Day/Night camera (with IR Cut-filter) and has three levels of SSNR for noise-free images (both colour and monochrome) and is IR sensitive. It has Sens-Up (Frame Integration) which can be used to give clear images where ambient lighting is poor and IR light cannot be used. It also has WDR (Wide Dynamic Range) to help see clearly when looking at a brightly backlit scene such as shop entrances/windows or car number plates at night.
The SHC-721A also has a variety of white-balance settings to help counteract the effects of low-pressure sodium lighting (orange street lights) on colours. Other facilities such as motion detection and privacy zones round off this camera’s impressive specification.
Typical Applications: It may be argued that some of the above features are mutually exclusive, such as IR sensitivity and Sens-up for instance. However, there are applications where both can be useful, such as town centres where evidential quality images are required from many and varied lighting conditions, including low-pressure sodium (from street lights), tungsten-halogen and fluorescent (from shops and car headlights) and IR (from private security camera systems) and areas where there is little or no lighting (such as alleyways, churchyards, cemeteries etc.)
The SHC-721A can automatically deal with these changes in lighting types and levels to optimise image quality. Other suitable applications would be any poorly lit areas such as rural locations.
SSNR (Samsung Super Noise Reduction) is a technology unique to Samsung and should not be confused with ordinary DNR (Digital Noise Reduction) techniques offered by other manufacturers. Not only does SSNR reduce noise to give clearer images, but also reduces ghosting and has a major additional benefit of reducing the file size of the recorded images – reduced by 70 per cent when using a MPEG format and by 40 per cent when using a JPEG format. This offers potential costs savings in respect of the size of the hard disc that is used in the recording device.
Whatever the application, noise inevitably creates the challenge. Noise occurs when AGC attempts to compensate for a weak video signal. It is usually the graininess and snow-type effects that render an image unusable before the actual darkness does. It follows, therefore, that if the noise could be removed, the images would still be usable and this is the idea behind the development of SSNR, Samsung’s Super Noise Reduction technology. With noise reduction techniques such as SSNR, CCTV systems can deliver excellent results even in the most demanding lighting conditions.
