Dynamic range compression and detail enhancement of sea-surface infrared image

Dynamic range compression and detail enhancement are two important issues for effectively displaying high dynamic range infrared (IR) images on standard dynamic range monitors. Sophisticated techniques are required in order to improve the visibility of the details without introducing distortions. To clearly show the highly dynamic infrared image of sea background, a high dynamic range compression and detail enhancement algorithm was presented which was made of three main steps. First, highly dynamic infrared image was enhanced by a multi-directional Laplacian enhancement method based on gradient edge information, and the first order gradient image smoothed was combined with multi-directional Laplacian filtering to enhance images. Second, the dynamic generalized histogram information of the enhanced image was obtained. Finally, the gray level grouping method was used to construct the mapping function, which maps 14 bits intensity in the input image to 8 bits intensity in the output image. As a result, infrared image with low dynamic range was obtained clearly. Experiments on a large number of sea-surface infrared images were conducted. The results verify that the proposed algorithm can improve the contrast of the image, effectively enhance the ship target details, suppress background noise amplification, and avoid the generation of halos. Therefore, the image with high quality was achieved.