Gain control is a critical, though often overlooked, factor in low light surveillance video. It is generally only noticed when the negative side effective of aggressive gain levels are seen, namely noise / snow on screen. The picture below, from one of our parking lot tests, is a prime example of this problem:
Clearly, the noise is a problem and ideally you would want to remove it. This raises important questions about how to use gain control effectively.
In the introductory video below, we provide a real-time demonstration of gain control:
To learn more, we conducted a series of experiments in a variety of scenes. For each scene, we captured video, images and bandwidth consumption. Here are the scenes we tested:
- Black and White Mode .5 Lux (Dark)
- Black and White Mode 20 lux (Low Light)
- Color Mode 4 Lux (Moderately Dark)
- Color Mode 300 Lux (Daytime)
Our testing was done across 3 HD cameras from Avigilon, Axis and Bosch to see a range of performances.
Inside the Pro section, we share our results and answer the following key questions:
- How significant does image quality vary with different gain control settings?
- Should you use gain control?
- What is the right gain control settings to use?
- What alternatives should you seek to using gain control?
- How do manufacturers approach to gain control differ?
- How does gain control differ between Black & White and Color modes?
- What is the bandwidth impact of different gain control settings? What impact does light levels have on bandwidth impact?
- What impact do VBR and CBR streaming modes have on using gain control?
- What impact does digital noise reduction (include 2D and 3D DBR) have?