Underwater Image Enhancement using Blending of Contrast Enhancement Techniques

Underwater images are useful in research of marine biology, oceanography, environmental monitoring and archaeological survey. However, underwater images have low contrast and are harmed by factors such as light attenuation, colour distortion, etc. Hence, underwater image enhancement is used to overcome above challenges and enhance the low contrast images so that it can be used for further applications. This work employs a mixture of two or more methods for contrast enhancement. CLAHE is utilised in conjunction with contrast enhancement techniques including DSIHE, RSIHE, and BBHE Non-reference performance metrics such as entropy, UIQM, UCIQE are used to evaluate contrast enhancement techniques. In this study, contrast enhancement techniques are applied on 1150 Underwater images. These underwater images are taken from two underwater image dataset called UIEB and EUVP and then combination of Global HE based contrast enhancement technique with CLAHE is applied. The combination of RSIHE and CLAHE outperforms all other methods in both UIQM value 2.6238 and entropy with entropy value 7.9867. Compared to other contrast enhancement methods used in the study, RSIHE followed by CLAHE with value 0.6621 and DSIHE followed by CLAHE with value 0.6651 perform better in the case of UCIQE.