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What is Digital Noise Reduction?

Noise – essentially static, causes interference in the video signal. These manifest as black & white grains in the video recorded by the security cameras, making the video take on a grainy appearance.

Normally in the day CCTV cameras have enough lighting to produce video with very little noise. Unfortunately, with the nature of how camera sensors work; video noise is unavoidable. It becomes more apparent when there is inadequate or low lighting. This makes it difficult for the camera to distinguish different colours/contrasts. All of this will create more noise in images as the sensor finds it difficult to produce a clear image; making the video take on a more grainy look.

Noise can also be caused by a nearby power interference, heat, or device algorithms.

Through the years of technological advancement, digital noise reduction was created and has been refined. Keep reading to learn about Digital noise reduction and the different types available in today’s Security surveillance cameras.

The different types of Digital Noise reduction

2D DNR – Temporal Noise Reduction

The first method produced thats still around to remove noise is 2D DNR (2D Digital Noise Reduction).

This is a form of temporal noise reduction. It works by analysing pixels in a frame and comparing them as part of the overall sequence. Then it looks for anything that doesn’t look consistent like artifacts and repairs them.

This is effective for basic purposes but has disadvantages.

Temporal noise reduction (2D DNR) is prone to creating bad motion blur (blur trails) when there is some movement. This affects video clarity & quality and makes surveillance difficult.

Going up in resolution, the effectiveness falls much shorter than 3D DNR which we’ll discuss now.

Notice how the 2D DNR analysed image is much blurrier. This is caused by Motion blur which is something 3D DNR aims to eliminate.

3D DNR – Spatial Noise Reduction

Another technology developed further on was 3D Digital noise reduction. This is a form of spatial noise reduction. 3D DNR is algorithm powered. It removes noise by using this algorithm to compare pixels in each frame individually and to compare frames to one another.

There are some clear advantages to using spatial noise reduction.

3D DNR works much better at removing noise from low-light videos.

It also works much better with movement caught in the frame of the video; meaning even quick moving objects will remain clear and without motion blur.

Due to it being controlled by an algorithm, it is much more capable of handling high resolution videos to produce crystal clear footage’ even in inadequate lighting conditions.


All of the new Hikvision ColorVu Camera require DNR in order to work. They provide 24/7 Colour recording. Click on the camera to check them out!

Check out the Prolux 620 Series cameras. All of them come with the more advanced 3D DNR and Wide Dynamic Range. (Read more about that HERE)


Prolux 8MP Camera with 3d DNR WDR

True WDR & 3DNR by Prolux




Check out the cameras here

We hope you better understand Digital noise reduction and how it can help you 

Till later,
~ Ali Azizi
HDSecure Team

Explaining Wide Dynamic Range

Wide Dynamic Range, commonly seen written as WDR, is a technology used to tackle issues in video recording areas with high variance in lighting levels. Cameras equipped with WDR are able to tackle this in a couple different ways (we will get around to how), which helps show more information in terms of what gets captured by the camera; notably by improving image quality and obtaining a more uniform result, thanks to this dynamic treatment of light.

Figure 1: Comparison shot showing how some of Cameras like this 8MP Prolux Turret Camera will help create more accurate imaging.

A good example of this is when a camera is facing towards somewhere with a window. Inside the building will be darker than outside. This means the camera will either focus on the inside and not be able to see anything going on through the window or you will focus out of the window and everything inside will get dark. This can be a security hazard as you will have an area where you can’t view what’s happening.
This is where a WDR Camera comes to play. With such a camera, it will be able to see both areas inside the building and out of the windows with a much more uniform level of lighting without loss of quality; most importantly you will have no gap in your surveillance security!

Where WDR Shines

Cameras with WDR are ideal in different situations that require very high-quality monitoring. Some examples are:

Figure 2: Comparison image shows how WDR affects cameras image/video that have views with varying lighting conditions.

– When the camera has areas of dark and light in one frame e.g. looking out from inside a building or looking out from a parking lot which needs to register which cars come through & leave.
– Cameras covering entrances of modern office block reception areas with lots of large windows.
– Cameras looking through glass/window with reflections present; preventing proper illumination.
– Cameras facing an area with quickly changing light levels e.g. facing a busy street with car lights, facing areas with neon signs.

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Check out this Prolux 8MP 4K Turret Camera equipped with 120dB True WDR & 3DNR paired with Starlight Technology to provide Full-Colour Night vision in low light.
(click on picture to be taken to the product page)

How does Wide Dynamic Range work?

With WDR technology, the camera lens uses different shutter speeds to allow more light in darker areas & less light in brighter areas. The sensor’s exposure to light it receives from outside is controlled to achieve a compensated image. With powerful image processing power, This would then combine them into 1 image.

Figure illustrating how dynamic capture occurs with CCTV Cameras.
Figure 3: The Camera captures & combines several images with varying shutter speeds to form the final result in True WDR

True WDR cameras and Digital WDR (dWDR) cameras

When browsing for CCTV cameras, you will come across cameras with WDR. Use due diligence while browsing! Because although they may seem the same; they might not be. This is because there are multiple types of WDR; such as True Wide Dynamic Range and Digital WDR.

As written above, we have covered how True WDR works using different shutter speeds & raw image processing.
Digital WDR (dWDR) varies to this by using clever software to digitally retouch the image so darker areas are lightened and lighter areas darkened.

Hikvision’s Cameras with a Variety of WDR

Differences in image with True & digital WDR

As True WDR captures more information, there is a clear difference in video with True WDR compared to dWDR. Proper WDR achieves a more optimal overall illumination and captures more detail in all areas as well. To do this, they require a greater capacity for image processing. For this reason, True WDR cameras, although more expensive, achieve better results. Check out this Prolux 8MP Turret Camera sporting True WDR, delivering the sharpest and optimally illuminated images on the market.

Figure 4: Comparison of varying images using different video processing technologies.
BLC (Backlight compensation) isn’t covered here but simply it works to brighten the whole scene on a video/image frame instead of balancing over/underexposed areas like WDR does, This can wash out some already overly-lit areas in an image/video.

Having said this, as you can see in Figure 4, comparing a camera with dWDR with a camera without the technology is a much more obvious difference because you lose out on a lot more information when there’s nothing able to balance the colour and light levels out. Check out this camera by Prolux offering 4K picture quality paired with dWDR and 3D DNR

Prolux PXC-622F8 8MP 4K Dome Turret Camera. Comes with Digital Wide Dynamic Range & 3DNR to produce Crystal clear images no matter the lighting conditions.
Prolux PXC-622F8 8MP 4K Dome Turret Camera. Comes with Digital Wide Dynamic Range & 3DNR to produce Crystal clear images no matter the lighting conditions.

Conclusion

Wide dynamic range was created to aid Surveillance cameras capture more colour accurate imaging. Especially when looking at more complex views with different light conditions.
Its important to consider this technology when choosing your Security Camera, be it HD Coaxial or IP.
Note: We still advise to not point cameras directly at strong light sources. This can damage the camera lense and reduce its lifespan.

Hopefully now you are more aware of Wide Dynamic Range (WDR), how it can help your surveillance system, and the varying types of WDR available on the market.
~Ali Azizi
HDSecure Team