Advances in CMOS sensors give rise to superior low-light cameras

Advances in CMOS sensors give rise to superior low-light cameras

A major trend in video surveillance these days is the emergence of cameras capable of recording in extremely low-light environments. Called low-light, starlight, or what have you, these cameras have sensitivity ratings from 0.01 lux (capable of shooting in a clear, moonlit environment) to 0.001 lux (capable of shooting in a clear moonless environment), making them ideal for various applications, such as city or warehouse surveillance, where low-illumination recording is key.

What has made this possible is advancement in the CMOS sensor technology, which has caught up with the CCD technology in terms of noise reduction, a critical element for shooting in low-light environments. This is especially the case after the introduction of backside-illuminated (BSI) CMOS sensors, which enable cameras to record in lower light levels and with much less digital noise.

Sony’s CMOS sensors featuring the STARVIS technology, for example, utilize the BSI mechanism. According to Sony, security cameras shooting at night often have their lens aperture fully open, bringing in abundant incident light. When using a front-illuminated structure, the wiring layer between the on-chip lens on the front surface of the CMOS image sensor and the photodiode that performs photoelectric conversion blocks part of the incident light, thus lowering the sensitivity. In contrast, the back-illuminated structure adopted by STARVIS does not have a wiring layer that blocks incident light above the photodiode, dramatically increasing the light utilization efficiency.

OmniVision Technologies, a developer of advanced digital imaging solutions, has also announced the OV2718, a high-definition camera chip sensor designed for high-performance security cameras. The 1/3-inch OV2718 leverages OmniVision's OmniBSI-2 pixel architecture to deliver best-in-class low-light sensitivity, high dynamic range (HDR), and 1080p HD video, making it well-suited for mainstream security and surveillance systems.

Camera manufacturers, meanwhile, have also rolled out their low-light cameras utilizing the latest CMOS technologies to help users with their low-illumination surveillance needs.

As an example, Qihan has launched a new product line based on the STARVIS technology, featuring cameras that offer clear and relevant images regardless of the lighting condition. The QH-NW751DS-P model comes with sensitivity of 0.001 lux and can record at 6MP non-real time and 30fps at 4MP, making it an ideal solution in projects where low-light surveillance is needed.

Dahua Technology, meanwhile, has also announced its Starlight network series cameras with 0.005 lux sensitivity. The cameras feature 2-megapixel, 1/1.9-inch progressive scan CMOS image sensors for capturing full color images, as well as support up to maximum 50/60fps at 1080P encoding. According to Dahua, verticals that can benefit from the cameras include transportation, retail, and parking management.

Bosch Systems’ Dinion IP starlight 8000 MP camera also features the latest sensor technology. Combined with sophisticated noise suppression, the camera enables sensitivity of 0.0121 lux at full 5MP resolution in color and even 0.00825 lux at 1080p resolution. The device also features an intelligent auto exposure function, offering superb front-light and backlight compensation by automatically adapting to changing light conditions. When selecting these low-light cameras, the first step should be to gain an understanding of the various applications that require low-light and night-vision features, in addition to the camera specifications. This ensures that the most appropriate cameras are selected for the environment of the project in question.



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