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Cortex Security Solutions

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What is 2D and 3D Dynamic Noise Reduction (DNR)?

Signal distortion, or "noise", is an unavoidable by-product of amplifiers. Even when working at optimal level, digital amplifiers, whether used in audio or video applications, create some noise.

Video "noise" can take the form of "static", fog, speckles, haze, fuzz, transparent color bocks and other visual artifacts that make your security camera images look less than crystal clear. Therefore noise reduction is an important aspect of surveillance camera design and selection. It becomes even more important as  display technology advances and gives people the ability to view higher and higher resolution images.

 Various methods have been used over the years, implemented through hardware and software, to clean up video generated by CMOS and CCD video sensors. One of the simplest forms of noise reduction compares one frame to the next, and removes any oddities that do not appear in each frame. Complex algorythms determine exactly what is an "oddity" to be removed. This is an example of "temporal noise reduction".

Temporal noise reduction is not sufficient for high resolution imaging, especially if it involves moving objects or low light imaging. 2D-DNR is a form of temporal noise reduction, and was developed to work with low light images.

2D-DNR works best to clean up the foreground of an image. This can noticed when you look at security camera footage of a street lamp at night, for instance. The area closest to the camera will appear to be clear, while areas further away will appear "salt-and-peppery". Moving objects can also be an issue in a strictly 2D-DNR system, and can appear blurry or leave fading trails. Movement can "confuse" the 2D-DNR system. 3D-DNR was designed to remove this limitation.

3D-DNR adds "spatial noise reduction" to 2D-DNR techniques. This type of noise reduction compares pixels within the same frame as well as frame-to-frame. It removes the grainy
appearance of low light images, handles moving objects without leaving trails, and makes images clearer and sharper.

Even if you don't care about image quality that much (and some people don't), there's another reason to want a camera with good noise reduction. If a security DVR is recording your surveillance camera footage, then it's also recording the noise. Noise, when it reaches your DVR, causes two issues you want to know about.

First, video noise inflates file size, since the DVR is recording the image plus the noise. A predominantly black, nighttime image that would normally create a small, compact .AVI file (for instance), will be forced to save all the salt and peppery spots, the haze, and the shifting patterns resulting from noise. Over time, file size adds up, and all hard drives have a limited storage space. It doesn't take a genius to see what will happen.

Second, video noise can trigger motion detection functions, if the DVR is set up to use them. This can cause false alarms, annoying emails from the automated notification system, and create associated problems. Police called to false alarms are generally not amused, and these incidents can result in a bill from your local police department in extreme cases.

Make sure to provide the highest quality cameras you can to  your clients before they have these problems. Getting a poor video image is often enough to make people want to buy a high quality camera. If it isn't, paying for more HDD space, or wanting a high quality motion detection system that avoids false alarms often changes their minds.

Many Cortex cameras are built from the ground up with 3D-DNR as well as other noise reduction techniques like automatic gain control (AGC) adaptive tone reduction (ATR), high/intense light reduction (HLR), and more. The list includes COR-HD5V,COR-HD7V, COR-HD80V, COR-HD59, and more. Call a Sales Representative (888-573-2333) today to see the entire list, and to get wholesale prices!