Theoretical analysis and improving method for the contrast of image under water

On the basis of scattering theory of Ocean Optics, the theoretical formula of the contrast of image under water is derived in this paper. In addition, a method for improving the contrast of image under water is put forward. Experiments of using symmetrical double light sources have been conducted, and show that the contrast has been improved more than twice of that using single light source. Theoretical results are in agreement with that of the experiments. Both theoretical and experimental studies reported here show that the symmetrical lighting system is an efficient method to improve the contrast of image under water.