Brightness adjustment and contrast matching in low-light underwater images using feedforward neural networks

Access to high-resolution underwater images is crucial for the conservation and development of marine resources. Light scattering and light absorption are two fundamental issues in improving the quality of underwater images. Many of the captured images have severe degradation, which harms the systems and activities that rely on these images. To address this problem, we introduce an auxiliary network to enhance the contrast of underwater images. This network consists of three critical components. In the first step, a decoder network is used to recover gradient maps and enhance the brightness of the images. Then, we take the help of a brightness adjustment network to control the brightness of the hidden image, and finally, we use an adaptive contrast module to adjust the contrast. To improve the performance, we use a normalizer module to solve the problem of not paying attention to the increase in image contrast when increasing the brightness. Evaluation of the proposed method with public dataset images shows that our method can increase the resolution of underwater images. In addition, the proposed model can increase the resolution of images in complex images, low-light, and dark conditions.