Image Contrast Enhancement for Deep-sea Observation Systems

This paper describes a novel method for enhancing ocean optical images using weighted guided trigonometric bilateral filter and spectral properties. While light traveling through the water, light rays are distorted depending on the wavelength. That is, absorption, scattering and color distortion are three major distortion issues for underwater optical imaging. Scattering is caused by large suspended particles, as in turbid water that contains abundant particles, which causes the degradation of the captured image. Color distortion corresponds to the varying degrees of attenuation encountered by light traveling in water at different wavelengths, causing ambient underwater environments to be dominated by a bluish tone. Our key contributions are proposed include a novel deep-sea imaging model to compensate for the attenuation discrepancy along the propagation path and an effective underwater scene enhancement scheme. The recovered images are characterized by a reduced noised level, better exposure of the dark regions, and improved global contrast where the finest details and edges are enhanced significantly. The experiments show that the average PSNR is improved by at least about 0.5 dB than the state-of-the-art-methods, and SSIM is improved about 0.05.