Infrared (IR) is invisible radiant energy, electromagnetic radiation with longer wavelengths than those of visible light. Human eyes only can see light with a wavelength between 320nm-760nm.Infrared, which spans 700nm to 1000nm on the EM spectrum, is beyond what the human eye can see, but the IP camera sensor can detect it and make use of it.

IR cameras detect these invisible infrared wavelengths, enabling the camera to see in the dark. Most IR cameras have a series of IR LEDs (often situated around the lens) that transmit infrared light at night, or whenever the camera switches to night mode. Since infrared light can interfere with color images, most IR cameras have an IR cut-off filter to block infrared light during the daytime. The filter sits between the camera’s lens and sensor, to allow visible light to pass through in the daytime, while blocking out infrared wavelengths. Once the light level drops to a certain point, the filter shifts to allow infrared light in.

This process is sometimes called True Day Night (TDN) because it delivers true color images during the day, and black and white or night vision images at night.In situations where there is minimal to no ambient light (for example, nighttime surveillance of retail stores or office buildings with no windows or natural light), even a TDN camera will not provide a crystal-clear image. You need powerful IR illuminators to light up complete darkness.

A common question that CCTV Camera Pros sales engineers are asked is “What is smart IR”? Smart IR is a technology built into some security cameras that adjusts the intensity of the camera’s infrared LEDs to compensate for the distance of an object so that the infrared does not overexpose the object.Smart IR technology was invented to solve the problem of infrared LEDs whiting out images, such as people’s faces, when they are too close to the IR LEDs of a night vision camera. Many infrared cameras that are available today include this technology, but not all do, so check your camera’s specification.

Smart IR vs No Smart IR Comparison

The below image compared a CCTV camera with smart IR to one without. The camera with smart IR that was used for the video capture had an infrared range up to 100 feet, but as you can see, it is able to adjust the intensity of the IR LEDs for the man that approached the camera within 3 feet.

IR Illumination is Even and Balanced