Low Light Level Color Night Vision Technology Study On Single-channel And Dual-spectrum

Color night vision technique obtains false color images of natural scene using differences from different spectrum wavebands, it can improve the quality of the output-image produced by the night vision system effectively, thus obviously enhances the target detection and the identification probability. Color night vision technique is one of the pivotal techniques which are current developing emphases in the world.On the base of analyzing the dual-channel systems: low light level and visible light, low light level and infrared light, low light level and ultraviolet light, low light level and laser assisted, a single-channel dual-band false color night imaging principium based on inter-frame compensation is proposed in this dissertation to realize originally dual-channel dual-band color night vision technique on single-channel system with a raster filter setting forward.The main researches in this paper are listed below: the optimal spectrum matching and filtering technique, the separation and compensation of dual-band low light level images, the fusion and color space mapping of dual-band low light level images, the establishment and experimental study of single-channel dual-band false color low light level night vision experiment device.The single channel dual-band low light level color night vision technique based on the inter-frame compensation has done a further step to the double channel color night vision theory and the engineering research .It is a new technical method to solve the problem of using single channel to realize color low light level imaging. The single channel dual-spectrum low light level color night vision technique will have the widespread application prospect in the domains of military, astronautics, public security, meteorology and so on.On the aspect of optimal spectrum matching filtering technique, best spectrum break point was chosen and designed according to the night natural radiation, the spectral characteristic of goal and background own radiation and reflection, as well as the spectral response of low light level CCD camera photocathode. The spectrum separation raster filter is put in front of the intensifier, and then the dual-band stripe low light level image with the short wave information and the long wave information in turn was collected.On the aspect of the dual-band low light level images separation and compensation, the technique of spectrum separation and compensation reconstruction were researched, the stripe low light level images were obtained from the scenery actual imaging with the 'long' wave information and the 'short' wave information in turn. The compensation method based on the horizontal collection, the sample block compensation method based on the correlation of the grey space and the inter-frame compensation methods were designed to compensate the split dual-band images. The simulation experimental study of the dual-band low light level image separation and the compensation technique were done, the results indicate that the above methods in the single channel dual-spectrum color low light level system have applied effectively, and have achieved the goal of the dual-band low light level image separation and the compensation.On the aspect of the dual-band low light level image fusion, based on the study about the characteristics of the low light level long wave image and short wave image separated and compensated from single channel, the single channel dual-spectrum low light level image fusion method was proposed: Fusion method based on pixel space correlation and wavelet layered fusion method. The image quality evaluation method based on the pixel space correlation was proposed and studied, and the fusion images were evaluated.The fusion results of fusion method based on the pixel space correlation and the wavelet layered fusion method were compared with those original fusion methods, such as gray scale modulation methods, the spectrum field fusion method and the unique ingredient fusion method. These two new fusion algorithms satisfy the real-time request, and have better evaluation results than the former application algorithms. The evaluation results based on the pixel space correlation method are consistent with the results of the classical methods.On the aspect of color space mapping, based on the analyses and researches about the four color night vision display methods: NRL, MIT, TNO and Toet daytime imitation display, the false color image obtained from the RGB channel mapping was carried on further adjustment to approach the daytime display. The adjustment method in the HSI color space was realized based on space correlation of brightness, color tone and color saturation.Based on the analyses and researches about the above theories and methods, the dual-band separation raster filter was designed and produced; the device of the single-channel dual-band false color low light level night vision based on inter-frame compensation was established. And the performance experiments and the correlation test were carried on the device. The processes of the design of the system's hardware and software are detailed in this paper as well as the system's experiment results. The single channel dual-spectrum low light level night vision system has many merits, such as compact structure, needless of image-matching, high quality-price ratio, and better real-time image sampling performance.