Research on Underwater Image Enhancement Techniques in Complex Scenarios

Abstract

This study utilizes algorithms such as the Laplacian operator and Dark Channel Prior (DCP) to enhance marine images. A model is established to represent common degradations in marine images, including low light, color cast, and blurriness. The image enhancement process involves grayscale conversion followed by linear enhancement of dark pixels. The proportion of dark pixels in each image is calculated, and an image is defined as having low-light conditions if this proportion exceeds 15%.For color cast assessment, the study employs the LAB color space. After converting the images, the values for the L, A, and B channels are computed. The variance of each image in this color space is calculated, and a threshold of -20 is defined. Images with a variance greater than -20 are identified as having a color cast. To evaluate blurriness, the Laplacian operator is applied to calculate the variance of each image. Based on a predetermined threshold, a determination is made regarding the presence of blur.Based on the above model, the specific degradation type of an image can be identified. According to the principles of underwater imaging, light is categorized into three components: the direct component, the forward-scattering component, and the backscattering component. Considering transmission and the distance light travels to the camera, a transmission function for light in water is established. This function is combined with the light attenuation coefficient to compute the scattering component of the ambient underwater light, ultimately yielding a degradation model for the underwater scene.