根据反射镜拼接型 CCD相机拍摄影像时发生渐晕的灰度分布特点, 提出了一种基于最速下降法的曲面拟合方法, 以消除渐晕现象。对反射镜渐晕的物理模型进行分析, 通过仿真提出了一种二维曲面模型来拟合图像灰度补偿算法, 推导 Hesse矩阵的相关系数, 通过 Hesse矩阵逐次迭代收敛, 最终获得二维曲面的相关参数值。仿真结果表明, 上述方法能够有效估计出不规则二维曲面的相关参数。通过对实际影像的处理结果表明, 本文方法能够有效去除影像的渐晕现象, 改善图像质量, 在测试平台上对有效像素为 782×582的单面阵 CCD实验影片进行处理, 程序运行时间为 24 ms, 可见, 本文算法完全满足实际工程需要。由于该方法不需要相关的光学和几何参数, 因此具有广泛的适用性。

According to the gray distribution character of vignetting image photographed by interleaving assembled CCD camera using reflector, the method of two-dimensional quadrics fitting based on steepest descent method is introduced in this paper to solve the problem. The gray compensation algorithm based on two-dimensional quadrics fitting using matlab simulation is introduced after the analysis of the vignetting physical model of interleaving assembled CCD camera using reflector. Parameters of Hesse matrix are also deduced at the same time. The simulation result has illuminated that the parameters of irregular two-dimensional quadrics, such as vignetting image gray level, can be estimated effectively by this method. The actual processing result shows the vignetting phenomenon can be removed effectively, and consequently the quality of image is improved. We have used the new algorithm to restore 782×582 gray image on the test platform, the programme’s running time is 24 ms, so the algorithm can completely meet the practical need of the projects. Since no relative optical and geometrical parameters are needed, this method can be widely used in projects.