KEYWORDS: Cameras, Adaptive control, Light sources and illumination, Histograms, CMOS sensors, Night vision, Electric fields, Sensors, Power supplies, Image processing
Based on the working environment and characteristics of EBAPS cameras, a theoretical analysis is conducted on the relationship between camera exposure time, bias voltage, and image brightness information. An adaptive control method based on histogram feature function is proposed and implemented in the camera. Firstly, multi-point metering is used to extract regions of interest, and variable exposure time adjustment steps and bias voltage adjustment steps are designed to reduce the system metering calculation while improving the convergence speed and stability of EBAPS camera adaptive adjustment. The experimental results show that when the light intensity varies within the range of 10-4Lux to 100 Lux, the EBAPS camera can automatically adjust two parameters included bias voltage and exposure time, to stabilize the brightness of the output image, improve the image information entropy and the dynamic range of the camera. This method can also provide reference for subsequent image recognition and target tracking.
For the current brightness gain and maximum output brightness adjustment method of image intensifier has low efficiency, time-consuming, low precision, and other problems, this paper firstly studies a communication protocol from the perspective of digital communication of auto-gating power supply microcontroller. By means of communication with the host computer, the corresponding parameters of the internal program of the auto-gating power supply microcontroller are adjusted. Secondly, the hardware interface of the whole tube communication of the image intensifier is designed. Finally, the calibrated experimental device is used to adjust the brightness gain and maximum brightness of the whole tube, and the automatic brightness control function of the adjusted whole tube is verified. The adjustment time is short, the adjustment precision is high, and the matching between the auto-gating power supply and the image tube can be better realized.
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