As one of the important applications in Synthetic Aperture Radar(SAR) images

ship wake detection has been received considerable attentions in the area of marine remote sensing. Recently

most researches on ship wake detection depend on the mathematical tool of Radon transform. However

the result of Radon transform is the image with which wake character being enhanced but not the end points of the wakes. In order to calculate the ship's velocity

the aim of the research is to detect the end points of ship wakes. Found on the improvement of the conventional Hough transform

a normalized Hough transform algorithm based on grey level is proposed. It can make the detection result independent of the noise and the different lengths of different lines using the normalization technology. The steps of algorithm are presented. The expression of the wake's end points is derived. On the other hand

the calculation algorithm of ship's moving velocity is presented. Both the time complexity and space complexity of the normalized Hough transform and the conventional Hough transform are analyzed respectively. This algorithm is applied to the ship wake detection in SAR image. The experiments obtained good results and can extract ship's velocity automatically.