Abstract:In order to solve the problem of small underwater target detection and recognition, the methods of sonar image filtering, image segmentation and target extraction based on side-scan sonar are studied. Conventional filtering methods are difficult to effectively remove the noise in the image, resulting in degradation of image quality, in this pape, the non-local means filter algorithm and GPU acceleration method are used to obtain better processing results of sonar images, and to meet the real-time requirement of small underwater target detection, and adopts the method of combining the expansion algorithm with the Canny edge detection algorithm, effective discrimination of true and false underwater targets is realized.