针对航天图像舰船目标快速检测和船速估算的问题，本文首先对海陆背景图像特征进行了分析，以像素点梯度提取和边缘检测技术为基础，提出了一种基于梯度图三次滤波的目标提取算法，实现了海面区域和舰船目标的分割与提取。然后利用傅里叶拟合模型，提出了开尔文尾迹横波周期估算的方法，进而实现了舰船尾迹的快速提取和舰船速度估计。最后，定量分析了该计算方法的误差范围，讨论了误差来源。

For the problem of ship target fast detection and speed estimation of space-flight image, this paper firstly analyzes the feature of sea-land background image. Based on the pixel point gradient extraction and edge detection technique, a detecting algorithm based on gradient map three filtration is proposed. This algorithm can realize the segmentation and extraction of sea area and ship target. Then, by the Fourier fitting model, this paper puts forward a period estimation method of Kelvin wake to calculate the speed of ship. The error range and error source are analyzed in the end.