Small surface objects, usually containing important information, are difficult to be identified under realistic atmospheric conditions because of weather degraded image features. This paper describes a novel algorithm to overcome the problem, using depth-aware analysis. Because objects-participating local patches always contain low intensities in at least one color channel, we detect suspicious small surface objects using the dark channel prior. Then, we estimate the approximate depth map of maritime scenes from a single image, based on the theory of perspective projection. Finally, using the estimated depth map and the atmospheric scattering model, we design spatial-variant thresholds to identify small surface objects from noisy backgrounds, without contrast enhancement. Experiments show that the proposed method has real-time implementation, and it can outperform the state-of-the-art algorithms on the detection of distant small surface objects with only a few pixels.
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