Research On Infrared Small Target Detection Technology Under The Background Of Sea And Sky

In recent years,with the continuous development of infrared imaging and digital image processing techniques,infrared small target detection technique has been widely used in military,defense and civilian fields.When the small targets are in a complex sea-sky background,the signal to noise ratio of the image is relatively low,and the targets are easily drowned in the background clutter,causing leakage and false alarm.Therefore,how to detect small targets in infrared images accurately and efficiently under complex sea and sky backgrounds has great importance and practical use for the military and civilian fields.This dissertation focuses on the detection of small targets under the background of sea and sky,and is all around the following aspects.In view of the current large gap between the modeling and simulation results of the infrared background radiation on the sea surface and the real scene,this paper studies and analyzes the formation mechanism of the infrared background radiation on the sea surface,and introduces the appearance model of the ocean wave background.Based on the linear wave model and the two-dimensional wave direction spectrum,a three-dimensional wave height map is obtained by simulation,and the normal vector of each micro-surface element is calculated.Aiming at the restriction that the Cox-Munk reflectivity is only applicable to a specific observation angle,a sea surface reflectance solution method based on the bidirectional reflection distribution function(BRDF)is proposed,by which the reflectance at any observation angle could be obtained.At the same time,by considering the influence of spontaneous infrared radiation on the sea surface and the infrared radiation from the sun and the sky on the background radiation on the sea surface,the rules of distribution of infrared radiation on the sea background has been obtained.For the fact where the composition of sea clutter is complex and polytropic,and the targets in the image are easily covered by background clutter,a small sea surface infrared target detection algorithm based on the sea clutter curvature characteristics is proposed.The curvature characteristics of infrared sea clutter and small targets is analyzed,based on the difference between the curvature characteristics of the sea clutter and small targets in the orthogonal direction,and the orthogonal decomposition and combination result to the curvature map is obtained.Finally,the adaptive threshold segmentation method is used to extract the target from the fusion curvature map.The experimental results show that the algorithm proposed in this paper has a higher detection rate for detecting small targets on the sea surface under strong sea clutter.On account of the complex scenes such as islands and oil well platforms may appear in the scene,a small infrared target detection algorithm based on the combination of local maximum gray value and multi-scale local contrast is proposed.First,use the difference between the local maximum gray value characteristics of the background and the small target in the infrared image to distinguish the background from the target,and the local maximum gray value feature extraction map corresponding to the original infrared image is obtained.Then the multi-scale local contrast algorithm is used to suppress the background of the feature map to obtain the suppressed background.Compared with the original image,the new image effectively enhances the target while suppressing the background.The experimental data analysis results show that the algorithm has high detection rate and good robustness in complex sea-sky scenarios.