A unified total variation method for underwater image enhancement

摘要

Underwater images usually suffer from color casts and low contrast due to the absorption and scattering of light by the water medium. The degradation is caused not only by the light attenuation on the scene-sensor path but also by the light attenuation on the water surface-scene path. To eliminate the dual-path light attenuation, we propose a novel unified total variation method based on an extended underwater imaging model. Unlike previous variation-based methods that only consider light propagation along the scene-sensor path, we additionally include light propagation along the water surface-scene path in the underwater imaging model. In the proposed variational framework, we transform underwater image enhancement into two subproblems and construct different prior knowledge-guided optimization functions for them. The two subproblems aim to remove the light attenuation along the scene-sensor and surface-scene paths. Moreover, we present an alternating direction minimization algorithm based on an augmented Lagrange multiplier to address the optimization problems. The subjective and objective experimental results on underwater images with different attenuation characteristics demonstrate that the proposed method achieves good performance in underwater image enhancement.