Locating sea-sky line in infrared image based on complex degree calculation

Research on the location of sea-sky line under infrared complicated sea-sky background has the important value to improve the capability of far target recognition. In a real sea-sky background infrared image, the sky and the sea normally appear in the form of different changes of grey-level on account of their different infrared radiation and reflection characteristics. So we can use the background complex degree to differentiate between the sky region and the sea region. In our method, an operator is employed to calculate the background complex degree of image. By filtering original infrared image with the operator, the grey-level contrast between the sky region and the sea region can be stronger than original image. After the complex degree calculation, the edge detection with only row directional gradient and Hough transform are utilized in succession, the sea-sky line can be located. Some typical sea-sky background infrared images are selected to validate our proposed method. The experimental results indicate that our sea-sky line location method is robust.