Underwater De-scattering Range-Gated Imaging Based on Numerical Fitting and Frequency Domain Filtering
One of the major challenges of underwater imaging is its sensitivity to water scattering. In this paper, a method of underwater de-scattering range-gated imaging based on numerical fitting and frequency domain filtering is developed to suppress scatter effect and improve image quality. The backscatter noise is eliminated by using its numerical fitting value after measuring a sequence of water scattering maps. The Jaffe-McGlamery computer model and the light propagation property in water are introduced, and forward-scatter noise is reduced by filtering process in the frequency domain. After removing the backscatter and forward-scatter noise, the resolution and contrast of gated images are improved. A range-gated imaging system is established, and experiments are conducted in pools to prove the effectiveness and superiority of the proposed method. Compared with traditional range-gated imaging, the results demonstrate that the proposed method increases the image entropy by about 69%. The research is beneficial for enhancing underwater range-gated active imaging.
KeywordsUnderwater range-gated imaging Laser imaging Water scattering Forward scatter Backscatter Image enhancement
The authors acknowledge the financial funding of this work by the National Key Research and Development Program of China (Grant 2016YFC0302503), the National Natural Science Foundation of China (NSFC) (Grant 61875189), and the Youth Innovation Promotion Association CAS (No. 2017155), the Strategic Priority Program of the Chinese Academy of Sciences (No. XDC03060102).
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