| One of the important areas of marine technology research is seabed survey technology.At present,the observation methods of the underwater world are mainly divided into two types: one is the long-distance survey based on sonar images;and the other is the close observation based on the underwater imaging.The resolution of images taken by long-distance observation is relatively low,and it is mainly suitable for searching for objects on the seabed in a large range;while seabed images have high image resolution,rich color information and clear texture details,so the seabed imaging technology has gradually become marine research The core technology of the field.However,the coverage of the images captured by close observation is small,so it is necessary to use stitching technology to stitch multiple images for observation,and there are two main problems with the images captured at close range: First,the use of artificial light source system illumination and the existence of the seabed ground The undulations of the terrain cause inconsistent illumination in the seabed image;the second is the serious attenuation and reflection effects of the underwater incident light,which causes the seabed image to have problems such as reduced contrast and blurred texture information.Therefore,the original image is directly stitched,and the result is obvious seams and low contrast.Based on this,this paper conducts a comparative and systematic study on the image enhancement methods in seabed image stitching,and the main contents are as follows:(1)Research on the illumination uniformity and consistency compensation algorithm of seabed image based on depth information.Aiming at the inconsistency of image illumination after imaging at different depths of the seabed,a seabed image illumination compensation algorithm based on relative depth information is proposed.The algorithm determines the relative depth information according to the overlap area of adjacent seabed images,and uses linear interpolation to select different illumination compensation templates for different depths to compensate for the uniformity and consistency of illumination of the seabed image.Experimental results show that the algorithm can effectively reduce the influence of artificial light sources and seabed topography on seabed images,and the sequence images have good consistency.(2)Research on underwater image enhancement algorithm based on multi-scale Retinex theory of color restoration.Aiming at the problem of low contrast in the seabed image after illumination compensation,this paper proposes an algorithm.The algorithm first converts the seabed image from rgb space to HSI space,and extracts its brightness image,enhances the brightness component in the HSI color space in the frequency domain with MSR algorithm,and uses "gain/offset" to cut out the histogram To enhance the contrast of the tail pixel value,and finally perform color restoration.The experimental results of a large number of seabed images show that this algorithm can effectively improve the contrast of seabed images without destroying the consistency of the images,and the color of the seabed images is also guaranteed.(3)Develop a prototype software system for image enhancement in seabed image stitching.The main functions of the system include image input module,illumination compensation module and submarine image enhancement module.Experiments show that the system has high reliability and strong practicability. |
