When shopping for a security camera, one of the specifications that can be listed is Digital Noise Reduction (DNR). Despite the name, this term is not related to audio. When we mention noise in video surveillance, we are referring to image noise. But what is image noise? Image noise is almost like static. For example, when you watch television with a poor signal, the images will look grainy and have lots of speckles. Video surveillance footage with a lot of image noise will look like this as well. In order to reduce the appearance of image noise, we need to apply digital noise reduction techniques.
Why Is This Important?
The main reason why people use digital noise reduction methods is so their surveillance video will look more clear and crisp. Having clearer footage allows people to monitor activity better because they would be able to see everything that happens. For example, if someone happens to rob your house in the middle of the night, you would want your footage to have the best quality as possible so that you can have evidence to show the police.
Another reason why digital noise reduction is important is because doing this makes files smaller for more storage. An image with a lot of image noise will be a larger file size because all of the speckles and spots are still on that image. By getting rid of image noise, the file size will decrease because there will be less things on the image to be saved. Video recorders have a limited amount of storage space available so using this technique would be beneficial for storage conservation.
Types of DNR
2D DNR/Temporal Noise Reduction
2D DNR is the simplest method of noise reduction. It works by comparing each pixel on every frame and will remove any pixel that does not appear on every frame since these pixels will be detected as image noise. This method is effective and best suited for lower resolution images. However, one drawback of using this method is that it will blur or leave “fading trails” on movement.
3D DNR/Spatial Noise Reduction
3D DNR is similar to 2D DNR in that it compares each pixel on frames, but it also uses an algorithm to see which pixels change or move to identify which pixels represent image noise. Compared to 2D DNR, this technique is better at removing the grainy appearance that occurs on images that were taken in low-light and it doesn’t blur motion.
2D & 3D DNR Combined
Some cameras are capable of combining 2D DNR and 3D DNR for clear footage with minimal image noise. By combining these two, each method’s shortfalls are made up by the other’s strengths. Doing this allows you to take advantage of 2D DNR’s efficiency and 3D DNR’s ability to work on motion in order to get the best result.
Digital noise reduction is an important method that will allow you to record footage with more clarity but less space. We hope that this guide helped you to understand what DNR is and the different types that are available so you can choose the right security camera.