Background: Aiming at the problems of color distortion, low clarity, and poor visibility
of underwater images caused by a complex underwater environment, a wavelet fusion method,
UIPWF, for underwater image enhancement is proposed.
Methods: First of all, an improved NCB color balance method is designed to identify and cut the
abnormal pixels and balance the color of R, G, and B channels by an affine transformation. Then,
the color correction map is converted to CIELab color space, and the L component is equalized
with contrast limited adaptive histogram to obtain the brightness enhancement map. Finally, different
fusion rules are designed for low-frequency and high-frequency components, the pixel level
wavelet fusion of color balance image and brightness enhancement image is realized to improve
the edge detail contrast on the basis of protecting the underwater image contour.
Results: The experiments demonstrate that compared with the existing underwater image processing
methods, UIPWF is highly effective in the underwater image enhancement task, improves
the objective indicators greatly, and produces visually pleasing enhancement images with clear
edges and reasonable color information.
Conclusion: The UIPWF method can effectively mitigate the color distortion, improve the clarity
and contrast, which is applicable for underwater image enhancement in different environments.