The cameras were installed at a working site, and the end user allowed us to take control of the system over a weekend to carry out the various assessments. Because HD and megapixel cameras can suffer in low light, noise reduction is often one of the problem functions!įor the purpose of this test we used cameras from Axis Communications, Samsung Techwin and Panasonic (see Equipment panel for further information). In many Benchmark camera tests, we have seen image degradation caused by certain combinations of video processing. Where a camera requires other processing such as WDR, highlight compression or BLC, there will be a need for balance between all processing elements. Noise reduction is achieved through processing of the video image, and as such the actual reduction itself can have a detrimental effect on quality. Translate that into the real-world, and problems can surface.
It is simple to set up a camera in a sympathetic environment to show clean images in low light. It is a rare camera which does not include noise reduction, and whilst manufacturers have tweaked their methods, the bottom line is that the reduction of noise is dependent upon a number of criteria. Because it is seen by compression engines as change within the image, noise can increase bandwidth and storage needs, and that equates to a system with a higher cost-of-ownership. With systems using image compression, noise can have another negative impact. It doesn’t look good, and whilst it is typically the result of a camera being made to work beyond its capabilities, it gives the user an impression that their investment has been wasted on an inferior system. Whilst this does amplify video information, it also amplifies other parts of the signal too, and this results in noise. Most cameras’ DSPs use gain to amplify the video signal. It’s physics, and all the marketing spiel in the world can’t change that! Getting an appropriate amount of light to fall onto significantly smaller pixels creates difficulties. The higher number of pixels on an HD or megapixel chipset means that each image element is considerably smaller than on a standard resolution sensor.
For the installer and integrator, it makes sensitivity specifications pointless when trying to ascertain the likely performance in the field.Īs image resolutions increase, so working in low light becomes more of a challenge. Whilst there have been advances with regard to processing, they are nowhere near as dramatic as the figures indicate. The main reason for these dramatic reductions is not because cameras are significantly better with regard to low light performance, but because manufacturers now measure sensitivity in different ways. You would be forgiven for thinking that a drop in specifications from 10 lux to 0.001 lux is a sign of great innovation, of rapid developments in technology, and therefore a cause for celebration in the surveillance sector. Indeed, some cameras’ specifications are into three decimal places, such as 0.001 lux!
VIDEO DENOISE PROFESSIONAL
This wasn’t surprising as most professional manufacturers quoted such figures.Īs time passed, the specified figures dropped, and today it is not unusual to see camera specifications with a sensitivity figure that is below 1 lux. When the team at Benchmark first started testing video surveillance cameras many years ago, our specified low light criteria showed that most devices had a sensitivity of around 8-10 lux. Benchmark assesses noise reduction to see whether it delivers the required functionality. Noise can be a significant issue with regard to video performance, and addressing it not only increases quality but makes the cost-of-ownership more palatable. The vast majority of video surveillance cameras feature noise reduction technology.
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