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

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Dynamic noise reduction is caused by gain amplification in security camera processing. Signal distortion, or "noise", is an unavoidable by-product of amplifiers in digital processing for cameras. Even when working at optimal level, digital amplifiers, whether used in audio or video applications, create some noise. This happens in both Analog CCTV cameras and digital SDI cameras / IP security cameras since all use some signal gain software in the digital signal processor hardware. 

Video "noise" can take the form of "static", fog, speckles (Snow), haze, fuzz, transparent color blocks 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 resolution images like UHD (4K) and 8K CCTV.

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 algorithms 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 security camera images that are amplified.

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 security 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. All of the amplification processing can also add some levels of motion blur and shutter speed delays so amplification should always be used sparingly.  

Even if image quality is not the main goal, 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, night-time image that would normally create a small, compact files would run much larger sue to alternating noise. Compression codecs like h.265 and h.264 will be forced to save all the salt and peppery spots, the haze, and the shifting patterns resulting from noise at much larger file sizes. Over time, file size adds up, and all hard drives have a limited storage space. This is a problem that can be prevent with good WDR.

Second, video noise can trigger motion detection if the DVR is set up to use it. This can cause false alarms, annoying emails from the automated notification system, and create storage consumption complaints.

The continuous balance of amplification through signal gain controls and digital filters like WDR are an important part of the programming steps. Quality control programs like Cortex QC6 insure that your users will enjoy the best settings available.  

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 positives often changes their minds.

Using the trademark QC6® system, many Cortex® security cameras are built from the ground up with balanced 3D-DNR as well as other noise reduction techniques like advanced automatic gain control (AGC), adaptive tone reduction (ATR), high/intense light reduction (HLR), and more. The list includes COR-HD89TRV, COR-HD80V, COR-HD88TRV, and more. 

Call a Sales Representative (888-573-2333) today to see the entire list, and to get wholesale prices!

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