How Infrared Night Vision works on a Security Camera

CCTV security cameras, like many other cameras out there depend on external lighting to illuminate the scene. Without proper lighting, especially when it’s night outside, the footage cannot be interpreted. Fortunately, with the help of Infrared Night Vision, it’s possible to capture footage even when it’s pitch black outside. So in this article, we will discuss Infrared technology and how to best utilize it for your security cameras. 

What is Infrared Night Vision on a Security Camera?

Infrared and Visible light are different wavelengths of the electromagnetic spectrum. Although visible light (as the name suggests) is visible to us, Infrared radiation behaves almost the same way but it is invisible to the naked eye and it can be used by cameras to capture images when there is no visible light.

Therefore, with the use of Infrared radiation, security cameras can develop their own “Night Vision” system to see in the dark without the help of any visible light sources. For security cameras, this method is very useful as it allows the cameras to stay hidden while they are recording.

IR LEDs Illuminators Explained

For security cameras to capture night vision footage via Infrared radiation, they need to light up a scene with IR (Infrared) rays and then detect the reflected IR rays just like a normal camera would. Therefore, to “illuminate” a scene for night vision the cameras need LEDs or bulbs that emit IR radiation. 

Even though IR radiation exists in the environment, they are not bright enough for the cameras to form a clear image. So when it starts getting dark the cameras switch over to IR mode by removing their IR filter and switching on their IR illuminators. 

These IR LEDs look like regular LEDs but humans cannot see them when they are powered on. (Unless they look through a camera that doesn’t have a built-in IR filter.)

IR Cut-Off Filter Explained

For security cameras, the sensors that detect visible light waves and Infrared radiation are almost the same. Therefore when there is enough visible light in the environment, the camera sensors can form a clear image with just the help of the visible light spectrum, and in some cases, the IR radiation on top of the visible light spectrum can cause unwanted noise in the image.

To avoid this from happening, the cameras have a filter that is dedicated to blocking out IR radiation coming into the sensor. During the day, when there is enough visible light, the filter covers the sensor and restricts any IR radiation. At night, when there is almost no visible light, the filter moves away and the camera switches to night vision IR mode. 

IR Distance and Lux Explained

IR distance is related to the IR spectrum and Lux, which is also called Luminous flux per unit area, is related to the visible spectrum. 

For security cameras to use “night vision” through Infrared radiation, they need to have an IR LED or illuminator to flood the area with IR rays. Various IR LEDs are categorized by the intensity of IR rays that they can give out, and the simplest way to define the strength of these IR radiations is the maximum distance to which these LEDs can send out IR radiation. Although it’s considered a useless spec when comparing security cameras, having a greater IR distance (something that’s greater than 20ft) is always better. 

Lux is a different spec that is used to measure the quality of the camera when it comes to capturing visible white light. In the simplest of terms, the Lux value of a security camera determines the minimum amount of visible white light required by the camera to create a noise-free clear image. Most cameras advertise their minimum Lux value as something as low as 0.1. (Which is considered the same amount of light that is emitted by a full moon.)

What is Dynamic/Smart Infrared?

The ability to utilize infrared radiation to capture images is a very useful feature for security cameras. However, despite its ability to “see” through pitch-black darkness, just like too much light can ruin an image, too much IR radiation can also ruin a CCTV camera’s footage. 

To avoid the IR illuminators from “over-illuminating” a scene, manufacturers have developed the Dynamic/Smart Infrared feature, which automatically adjusts the intensity of the IR illuminators so that the image/footage is clear enough to interpret. 

So while Dynamic Smart IR is turned off, the IR illuminators are on full-blast, and whenever a person or object comes too close to the camera, it creates a “whiteout” effect where everything gets overexposed. When this setting is turned on, the system recognizes that the image is over-illuminated and lowers the intensity of the IR LEDs to make the image clearer. Also, this works the other way around when the system determines that the environment is under-exposed. 

Tips to improve your security camera’s infrared night vision

Just like prevention is better than cure, the best thing you can do to improve the footage of your security camera is to keep using the camera in the visible light spectrum. This involves leaving the lights on all night, installing motion-activated lights or solar-powered lights. Although this method uses visible light instead of IR, the footage will always have color and contain more information than black-and-white IR footage.

With that being said, if you prefer to keep things dark and surprise intruders instead of warning them, you can use the IR feature and improve the surroundings by adding external infrared sources instead. Make sure there are no over-illumination issues and that there’s enough power for these external devices. 

Other than that, several other tips and tricks which are common to both the visible light and IR domain are:

  • Cleaning the camera lens regularly
  • Make sure your camera switch to night mode
  • Choosing the right camera for the location (make sure every point of interest is in focus and not too far. You can read up about DORI here)
  • Changing the Dynamic IR settings depending on the scene (Dynamic IR is not recommended for a large outdoor setting.)
  • Installing the cameras away from light sources. (Don’t want the footage to get over-exposed.)

Other than that, you can also pick out a camera with specs (such as megapixels, resolution, focal length, etc..) that match the area it is supposed to cover.

Difference between Infrared and Full-Color Night Vision

Although it was used for ease of advertising, Infrared and “Night Vision” are two different things. As always, their main difference is in between the frequency spectrum i.e the line that’s drawn between visible white light and infrared radiation. 

Color night vision is a technology that was developed to make it possible to replicate a well-lit and natural image using only a small amount of visible light. Therefore, Full-Color night vision doesn’t rely on IR radiation. 

However, despite their success, Full-Color Night Vision systems always require a light source. Therefore, if the ambient lighting is almost nonexistent, Full Color Night Vision will not work properly, and instead, the cameras will switch over to IR which can function on their own. (As long as the IR illuminator is working.)


IR technology has become a staple of most modern security cameras. Their ability to replicate a black-and-white image without any visible white light is very impressive and allows security cameras to be set up in pitch-black environments. Although IR radiation does a good job of recording faces and license numbers without any issue, their lack of color is a significant drawback.


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