针对夜视系统前加入窄带滤光片会使其输出图像的信噪比大幅降低的问题,设计了基于负滤光片的真彩色夜视系统,并分别以标准比色板和自然景物为探测目标,设置与基于窄带滤光片真彩色夜视系统的对比实验,利用输出的真彩色夜视图像边缘图与参考图像边缘图的相关系数值来间接评价信噪比。结果表明:在实验一中,当环境照度为0.51 lx时,基于负滤光片的方法与基于窄带滤光片的方法相关系数持平,当照度分别为0.12,0.04,0.01 lx时,前者相对于后者相关系数分别提高了14.9%,26.8%,128.0%;在实验二中,前者相关系数亦高于后者。故与传统真彩色夜视系统相比,基于负滤光片的真彩色夜视系统可工作于更低照度条件下,能够输出具有更高信噪比的真彩色夜视图像。

Adding a narrowband filter in a night vision system can considerably reduce the signal-to-noise ratio(SNR) of output images. To solve this problem, a true-color night vision system based on minus filters is designed. Two comparative experiments involving the detection of a standard colorimeter and natural scenery using the true-color night vision system based on narrowband filters under different ambient illumination are performed. The SNR is indirectly evaluated using the correlation coefficients between the edge maps of the reference and output true-color night vision images. In experiment 1, the results show similar correlation coefficients for the two systems when the ambient illumination is 0.51 lx. For illumination levels of 0.12, 0.04, and 0.01 lx, the correlation coefficients of the proposed system are 14.9%, 26.8%, and 128.0% higher, respectively, than those of the system with the narrowband filters. In addition, the correlation coefficient of the proposed system is also higher than that of the traditional system in experiment 2. Therefore, compared with the traditional true-color night vision system, the true-color night vision system based on minus filters can work under conditions of lower illumination and produce true-color night vision images with higher SNR.