In recent years, camera modules have evolved from simple image capture tools to sophisticated optical devices. Previously, many systems focused on image quality in the visible light range. However, as application scenarios expand, how to obtain high-quality images in low-light environments has become increasingly critical.
CMOS and CCD camera sensors perform well in daylight and can detect near-infrared light that is invisible to the human eye, but may cause image color distortion. Therefore, understanding and effectively managing infrared light is very important to ensure that the image is authentic.
Below, let's quickly understand what "infrared" means.
What is Infrared?
Infrared (IR) is also known as infrared radiation, is a type of electromagnetic radiation with a longer wavelength than visible light. The human eye can usually perceive light with a wavelength of 320 nanometers to 760 nanometers, while infrared light has a wider wavelength range on the electromagnetic spectrum, usually between 700 nanometers and 1 millimeter.
This range is far beyond the scope of what the human eye can observe, so if you want to capture images in this wavelength range, you need specific camera technology, such as a specialized near-infrared (NIR) camera.
What is an IR-cut filter?
IR-cut filter, or infrared cut-off filter, is a precision mechanical shutter design. Its main purpose is to selectively block or allow infrared light to pass through, ensuring high-quality images with true color reproduction under different lighting conditions.
Unlike the human eye, camera sensors are very sensitive to near-infrared light outside the visible light range. In order to make the images captured by the camera more consistent with the visual perception of the human eye, most OEM cameras are equipped with an IR-cut filter, which only allows visible light to pass through while reflecting or absorbing unnecessary infrared light.
How IR-cut filters work
The working principle of infrared cut filters is clever and efficient - controlled by a motor or electromagnet. When there is sufficient light during the day, the IR-cut filter will open, blocking infrared light from entering the sensor and allowing only visible light to pass through, avoiding the interference of infrared light on the image color and ensuring the accuracy of color - just as the human eye sees. This process is also called "True Day and Night" (TDN).
When the ambient light becomes dark or enters night mode, the IR-cut filter will automatically turn off or move away. At this time, the camera sensor can receive all light, including visible light and infrared light, and with infrared lighting (such as infrared LEDs), it can capture clear black and white images at night.
Three key reasons to use infrared lenses filter
Integrating IR-cut filters in embedded vision applications is not accidental, but based on a variety of practical needs.
1. Ensure true image color
During the day, the intensity of infrared light in the environment is high. If the camera sensor directly receives infrared light, the image color will deviate significantly, for example, green plants may appear purple, or black objects appear gray. IR-cut filters ensure that the image colors captured by the camera in day mode are highly consistent with the real colors seen by the human eye by accurately filtering infrared light. This is crucial for color recognition, quality inspection, and the chain of evidence of surveillance video, and effectively solves the pain point of image distortion.
2. Improve night vision performance: say goodbye to blurry filter night vision
When the light is insufficient or in complete darkness, the IR-cut filter is automatically removed, allowing the camera to make full use of infrared illumination. In this mode, the camera sensor is able to capture infrared light that is invisible to the human eye, thereby generating clear, high-contrast black and white images without any visible light source. This is crucial for applications such as nighttime security monitoring, industrial inspection, or outdoor environment monitoring. It greatly expands the use scenarios and performance boundaries of camera modules, and effectively solves the pain point of insufficient night vision capabilities of traditional cameras.
3. Enhanced versatility and adaptability: integrated ir uv cut filter
Many modern IR-cut filters not only block infrared light, but also take into account the filtering of ultraviolet light (UV) to form an IR UV cut filter. Ultraviolet light can also have a negative impact on image quality, such as causing the image to be bluish or blurred. Filters with integrated IR-cut and UV-cut functions enable camera modules to better adapt to various complex lighting environments, whether it is strong sunlight, cloudy days, or night, and can provide stable, high-quality image output. This versatility reduces dependence on specific lighting conditions, reduces the complexity of system design, and improves the robustness of the system.
IR cctv camera and its application areas
IR-cut filters are standard in modern video surveillance systems, especially IR CCTV cameras (infrared closed-circuit television cameras). It enables these cameras to present color images during the day and automatically switch to infrared mode for clear black and white monitoring at night. In addition, in intelligent transportation systems (ITS), cameras used for license plate recognition or traffic flow monitoring also widely use IR-cut filters to ensure recognition accuracy under different lighting conditions. Embedded vision applications such as industrial automation, machine vision, medical imaging, and wild animal monitoring all benefit from the seamless day-night switching capability and high image quality provided by IR-cut filters.
Summary
IR-cut filters are an indispensable component in embedded vision camera modules. Through intelligent optical filtering mechanisms, it effectively solves the problem of infrared light interfering with image color, and greatly enhances the camera's imaging capabilities in low-light or even no-light environments. For applications that pursue image authenticity, night vision performance, and environmental adaptability, choosing a camera module with integrated IR-cut filters is the key to ensuring efficient system operation and data accuracy. It is not just a simple optical component, but also a core technology that ensures high-performance operation of embedded vision systems around the clock.
Sinoseen helps improve your embedded vision system
Learn more about how IR-cut filters can improve your next-generation camera modules. Contact Sinoseen's team of experts today to get customized solutions so that your products can capture clear and accurate images in any lighting conditions.
