Tunable-liquid-crystal-filter-based low-light-level color night vision system and its image processing method.

We introduce and verify a single-channel time-division filtering low-light-level (LLL) color night vision system (3LCNV). The imaging scheme, comprising a tunable liquid crystal filter, three-generation GaAsP image intensifier, and CMOS camera, achieves LLL color imaging and ensures sensitivity. The image enhancement and color reconstruction algorithm flow suitable for LLL night vision combines overexposure-against white balance, color correction matrix (CCM) color correction, and color image denoising to improve color visibility and reduce color difference and image noise. The proposed night vision system extends the minimum working illuminance to 10(-4) lx and achieves natural and clear color LLL imaging, improving night-time observations. (C) 2019 Optical Society of America