Underwater image quality degradation by scattering

Image quality assessment is a challenging task. Numerous metrics and algorithms have been developed, with a fair share of these efforts focused on referenced targets. For applications associated with most civilian and military needs in the field of intelligence, surveillance, reconnaissance such that automatic target recognition is required, an objective, no reference metric is needed. The task becomes even more challenging when the signals obtained from the imaging sensor are time-varying, including those introduced by the turbulence induced index of refraction fluctuations along the imaging path. This study is aimed to develop an objective metric, tuned to be used for underwater imaging applications where the scattering degradations from particulates, as well as optical turbulence are present. Following recent research outcome, that spatial coherence length is a direct proxy to optical turbulence strength, we developed a metric based on this principle, while including the static scattering contributions with previous developed underwater image quality metric. The results show very good agreement with referenced metric such as the structure similarity image metric, as well as visual, subjective validation, using images obtained from both lab and field experiments.