Tricolor acquisition and true color images fusion method under low illumination condition

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.