鉴于低照度条件下彩色成像都是采用微光、红外、紫外等波段图像融合成假彩色, 提出一种利用滤光片过滤和像增强器增强的三基色获取及真彩色融合方法。采用F-P滤光片设计出了透射中心在三基色光中心波长的三基色滤光片, 对其光谱透过性进行分析; 通过旋转三基色滤色轮将目标反射光过滤, 使用像增强器对过滤后反射光增强, 借助FPGA编写的控制程序实现滤色轮转速和CCD摄像机成像时间的精确同步, 利用CCD摄像机获取经增强后的三基色图像, 实现目标三基色图像的动态采集。研制的样机在微光实验室进行了三基色采集及融合实验, 实验时光照度分别1×10-1 lx (等效于月光下)和1×10-3 lx(等效于星光下), 采集速度设置为60 f/s, 对获取的图像质量进行了评价。结果表明: 在照度为1×10-1 lx时, 融合后的真彩色图像在灰度均值、灰度方差和信息熵3项指标方面, 比3幅单色图像的平均值分别提高了5.06%、5.97%和1.08%; 在照度为1×10-3 lx时, 融合后的真彩色图像与3幅单色图像的平均值分别提高了13.18%、-9.86和8.65%。

In order to solve the problem of color imaging for low light level(LLL) mainly fused by LLL visible images, infrared images,ultraviolet images and other band images,and actually the fused color images are false color images which cannot reflect the color of object itself,a noval tricolor images acquisted and true color image fusion method was proposed based on filter filtering and image intensifier enhancing.The three primary colors filter was designed by using Febry-Perot (F-P) filter, and the spectrum transmittance was analyzed.By rotating tricolor wheel filter, the reflected light of the object was separated and then amplified through using a domestic ultra II image intensifier .By means of the field-programmable gate array (FPGA) control program,the precise synchronization of the tricolor wheel filter rotation speed and the charge coupled device (CCD) camera exposure time was achieved ,the CCD camera was adopted to capture the amplified images on image intensifier,and finally the goal for dynamic acquisition of the tricolor images was got . The true color imaging experiments were carried out by prototype system in LLL laboratory,the experimental illumination was 1×10-1 lx (equivalent to moonlight) and 1×10-3 lx(equivalent to startlight),and the tricolor wheel filter rotation speed was set to be 60 f/s ,furthermore,a set of images were adopted to conduct quality assessment.Experiment results show that when the illumination is 1×10-1 lx,compared with the average value of 3 monochrome images,the gray mean value,gray variance and information entropy of fused true color image is increased by 5.06%,5.97% and 1.08%,respectively;and when the illumination is 1×10-3 lx,the gray mean value,gray variance and information entropy of fused true color image is increased by 13.18%,-9.86% and 8.65%,respectively.