Research and Application of Thermal Imaging Mode and Image Processing Technology

Significance Infrared thermal imaging technology has a wide range of applications in military and civilian fields, and realtime digital image processing, as a key link of infrared imaging systems, has become an important part of thermal imaging technology research in China and abroad. With the development of infrared focal plane detectors (IRFPA) and intelligent image processing technologies, new thermal imaging modes and corresponding image processing methods have been continuously innovated, which have achieved some effective results. Progress We review the research and application of the research team in the new thermal imaging modes and their image processing technologies. 1) The non-uniformity correction ( NUC) method combining scene-based time-domain high-pass and air-domain low- pass filtering, namely ITHP & GM is proposed, which can effectively correct the "water streak" non-uniformity noise that the existing algorithm fails to effectively deal with, and the algorithm transplantation has been realized on the FPGA hardware platform and applied in a mid-wave infrared cooling thermal imaging camera. 2) The focal plane infrared polarizer arrays with 4-polarization and 3-polarization + 1 intensity division are designed and developed, and the coupling and imaging with the refrigerated MW-IRFP movement (320 pixelx256 pixel, 25 mu m) and the uncooled LWIRFPA movement (640 pixelx512 pixel, 17 mu m) are realized. A correction model of the front polarizer-based polarization thermal imaging system is proposed, which can effectively reduce the radiation and reflection effects of the polarizer in the optical path. 3) The overclocked high dynamic range ( HDR) thermal imaging experimental system based on 256x256 longwave IRFPA is developed and combined with the HDR image fusion method of multi-integration time image fusion- detail enhancement cascade, and real- time HDR thermal imaging ( with delay less than 40 ms) is realized, which can normally observe and identify targets under the background of strong radiation such as the sun, jamming bombs, and flames. 4) The bionic compound eye thermal imaging mode with the partially overlapped field of view of four apertures and four/ five apertures is proposed, and the experimental system of four-aperture bionic compound eye thermography based on 640x 480 and 80x80 uncooled IRFPA is built, which realizes variable spatial resolution imaging with a large field of view searching and high-resolution imaging of central field of view and verifies the characteristics and effectiveness of bionic compound eye thermography. 5) The TIV-Net algorithm for the conversion of thermal infrared to visible color images is proposed. 75000 pairs of image datasets are completed, and the real- time processing that is not less than 20 Hz is realized on platforms such as vehicle platforms and drones. The real-time conversion of day and night thermal images to natural color visible light images through deep learning methods is proven, which effectively improves the situational awareness ability of day and night human eye vision through thermal imagers. Conclusions and Prospects The research progress of the research team in new thermal imaging modes and image processing technologies is reviewed, including the NUC method combining scene- based time- domain high-pass and airspace low-pass filtering, correction model of division of focal plane infrared polarizer arrays based on infrared polarization imaging, front polarizer-based polarization thermography system, overclocking HDR thermal imaging experimental system of longwave IRFPA, bionic compound eye thermal imaging mode and its experimental system with the partially overlapped field of view of four apertures and four/ five apertures, TIV-Net algorithm converting thermal infrared to visible color images, etc. Such technology research has made innovative technological breakthroughs or has been applied, showing a wide range of application prospects, which can be an important direction for further research and expansion.