Min-Max

Imaging lidar systems are used from the air to generate images of submerged objects for detection and classification. In many cases, the distortion effect of optical refraction at the air-water interface dominant the image quality. In this paper simple, generalized algorithm is presented that produces significant image quality improvement. The method requires sequential pairs of images made with a rangegated imaging lidar system. One image is the image of the sea surface above the object and the second is the object image. All the local maxima and minima in the observed sea surface image are located. At these same selected locations the pixel intensity values from the object image are saved in a new output image file. The process is repeated for each pair of images, and an average intensity is computed when any given pixel is selected more than once. This averaging tends to reduce the effect of non-uniform illumination of the target due to wave focusing and defocusing. This algorithm that so called “Min-Max Method” demonstrates improvement in output image quality