Poor image quality in low light environments is a common and recurring problem many have faced. This problem can be the cause of major concerns, especially as the most crime happens at night.
The security of your premises, whether that's your home or business, is of the utmost importance, at both day and night.
Fortunately, this detrimental problem has been solved by Hikvision's range of ultra low-light cameras with DarkFighter technology.
DarkFighter Night Vision Sensor
In a surveillance camera, the quality of the sensor determines the quality of the captured image, especially in low light conditions. If a low-quality sensor is used, a poor image will be produced. Similarly, if a high-quality sensor is used, the image will be of extremely high quality.
Hikvision specifically designed their sensor to have an extremely high quality, as well as a high S/N ratio and increased Wide Dynamic Range (WDR). To further enhance low-light performance and improve light passing quantity, the sensor's single-pixel area is nearly double the size of a normal sensor.
Single Pixel Area: Conventional Camera (left) vs DarkFighter Camera (right)
DarkFighter cameras also have a backside illuminated sensor, which improves brightness by 30%. Hikvision achieves this by modifying the order of the photosensitive layer and metal layer within the sensor, resulting in decreased light reflection and increased light usage.
The DarkFighter lens employs an aspherical lens shape, which effectively reduces image aberration present in conventional cameras with a spherical lens. As the aspherical lens has a free-form surface, the lens improves light transmittance, and consequently, enhances image brightness at night.
The surface of the DarkEye lens is coated with multiple layers of anti-reflection coating. This improves IR performance and footage quality while preventing stray lights and halo-effects from influencing the image.
To ensure the captured footage is bright and detailed with very little noise, Hikvision has utilised an ultra-large aperture. As shown below, the footage with a smaller aperture (left) is dark and few details can be seen. However, with a large aperture (right), the image is bright, clear and easy to interpret.
Footage Comparing f/1.5 Lens (left) and f/0.95 Lens (right)
When the focal length is increased in varifocal lenses, the aperture typically decreases, degrading image quality. However, Hikvision ensures this isn't the case with a constant large aperture. When the focal length is adjusted, the aperture retains the same value, and the image remains just as bright.
Constant Aperture: Conventional Camera vs DarkFighter Camera as Focal Length is Adjusted
Self-Adaptive Image Signal Processing (ISP) Technologies
Security camera sensors transmit optoelectronic signals linearly, although the human eye senses light non-linearly. By adjusting the gamma curve to a non-linear configuration, Hikvision DarkFighter security cameras alter the image signal so it is more similar to how the human eye senses light. As a result, this enhances the image, providing more details in low-lighting environments.
Hikvision has implemented multi-exposure technology into these security cameras. This effectively increases the dwell of the charge accumulation, increasing the vividness of the footage and signal intensity. This is shown by the image below.
Multi-Exposure: Multi-Exposure Off (left) vs Multi-Exposure On (right)
Hikvision has combined this multi-exposure technology with smart gain control. This limits additional noise when the signal is increased. The noise is further reduced by the 3D Digital Noise Reduction (3D DNR) module in the ISP. As well as reducing noise, this effectively reduces bandwidth and storage.
Hardware Noise Reduction
To limit noise as much as possible, Hikvision has implemented a hardware noise reduction method known as full-frequency suppression technology. Similar to software noise reduction, hardware noise reduction ensures file sizes and storage requirements are kept low, minimising cost.
Anti-Fogging Glass and Non-Silicon Oil Heat Conduction and Dissipation
These two components of Hikvision's DarkFighter security cameras clarify images. As the name suggests, the anti-fogging glass prevents the Hikvision camera from fogging up. This is as multiple hydrophilic coatings are applied to the glass, reducing the surface tension of water.
The temperature of the sensor inside the camera can significantly impact the quality of the footage. When the temperature is raised in Hikvision's sensor, heat conduction material quickly absorbs the heat. This prevents the sensor from getting too hot, and hence, the image quality is not influenced.
With Hikvision's application of advanced technologies in combination with their implementation of intricate hardware, their DarkFighter range of CCTV surveillance systems has exceptional performance 24/7.