Research On Wide Dynamic Pseudo-color ICMOS Imaging Technology

With the progress of image intensifier and CMOS sensor technologies,the ICMOS image system has become the digital low-light video device with most rapidly growing and the lowest working illumination.In this paper,a wide dynamic range color ICMOS imaging system is developed with NSC 1105 CMOS sensor and the NVT-5 image intensifier.Considering the working principle of intensifier,an auto-gated power supply circuit is developed,further widening the dynamic range of the image system.Based on NSC 1105 CMOS image sensor,this paper developed the low-light image system mainly includes the hardware platform's design and construction,FPGA-based driver timing logic design and hardware algorithm development.Firstly,introduces the device selection and the hardware module with its schematic design,including CMOS driver circuit,AD chip peripheral circuits,DA chip peripheral circuits and power supply module circuit,etc.Secondly,completes the optimum design of driving timing of the system and the development of hardware algorithms,mainly including the optimization of driving timing of CMOS image sensor,the design of low-light image's noise reduction algorithm,low-light image enhancement algorithm and the natural-color mapping algorithm for grayscale image.In the image noise reduction algorithm,three kinds of noise reduction algorithms are simulated and implemented on the hardware platform,according the result of the experiment,a noise reduction method based on multi-frame averaging algorithm and Gaussian filter is adopted.Histogram equalization and divided liner stretch are combined to propose an adaptive divided linear stretching algorithm based on gray-scale statistics,algorithm has a better image enhancement effect proved by experimentation.Finally,further studied the working principle of the image intensifier,analyzing pros and cons of the existing Automatic Brightness Control(ABC)circuit.The design of the auto-gated power supply is accomplished,including the device selection,the circuit design and simulation,the verification of the main parameters and the final board test.The experimental results shows that the wide dynamic range of the ICMOS imaging system designed in this paper can reach 10-5lx to 17 lx.Color performance is in line with human eye observation habits,and the overall imaging effect is good.