Research On Infrared Small Target Detection Method Under Complex Sea Background

The sea surface target detection technology is the key to improve the sea area perception and monitoring capability.Infrared thermal imaging technology has been widely used in the sea surface target detection due to its advantages such as strong concealment,long range and allweather operation.However,under the complex sea surface background,the infrared target in the field of view generally has a smaller size,and the infrared radiation will also attenuate due to the water vapor on the sea surface,resulting in the weak intensity of the target in the image.At the same time,the sea surface background contains the interference of various clutter,which will change with the variation of climate and the fluctuation of sea surface,and seriously reduce the signal-to-noise ratio of image,thus causing the high rate of missed detection and false detection of target detection.In this paper,the small infrared targets detection method under complex sea surface background is mainly studied from the following aspects:To solve the problem of fringe non-uniformity noise in infrared focal plane array imaging system,a gray difference estimation based stripe non-uniformity correction algorithm is proposed.According to the inherent spatial characteristics of the fringe noise,the position of the fringe noise in each frame is judged.According to the gray difference between adjacent pixels at the noise position,the non-uniformity of the pixel there is preliminarily estimated,and the current estimated value is evaluated through the next frame of image,and the estimated value is improved according to the evaluation result.Experimental results show that the proposed algorithm can effectively suppress the fringe nonuniformity in infrared images.In order to detect the sea-sky boundary under the complex sea-surface background,the sea-sky background images are analyzed from a variety of gradient directions.It is found that sea clutter is obvious in gradient images of all directions,while sea-sky boundary is mainly reflected in the vertical negative gradient.For this reason,a new method based on multidirectional gradient is adopted.Clutter in a vertical negative gradient image is suppressed by combining gradients in other directions.Finally,the sea-sky boundary is detected by using the vertical negative gradient map after clutter suppression.Through several groups of comparison experiments,it is proved that the algorithm in this paper has strong detection ability.Aiming at the background suppression problem of complex sea surface,this chapter analyzes several groups of 3D grayscale images and high-frequency detailed images of complex sea surface background.It is found that the gray value of the whole sea surface changes obviously in the vertical direction,but is relatively stable in the horizontal direction.For this reason,a sea-surface background suppression algorithm based on row mean and mathematical morphology is adopted,and the detected sea-sky position is used to eliminate the interference of sky clutter in the image.Experimental results show that the proposed algorithm has a good suppressing effect on complex sea surface background.Aiming at the detection problem of small infrared targets in complex sea surface background,based on the traditional local contrast(LCM)algorithm and combined with the background suppression algorithm by row mean and mathematical morphology,an infrared small target detection algorithm suitable for complex sea surface background is obtained in this paper.The background suppression algorithm is used to eliminate the interference of sea surface strong clutter to LCM algorithm,and then the LCM algorithm is adopted to enhance the small targets in the background suppression results.And the threshold segmentation is improved to enhance the ability of the algorithm to distinguish the real target.Finally,the superiority of the proposed algorithm is proved by several comparative experiments.