基于退化模型的图像渐晕处理技术

Vignetting correction technology of images based on degenerate model

针对反射镜拼接光学系统中的图像渐晕问题进行讨论,从几何光学角度分析了反射镜遮挡导致的部分光线无法在像面上成像出现的能量损失问题,对渐晕能量分布进行了定量分析。根据分析结果,提出了一种适合反射镜拼接渐晕的退化模型,采用最速下降法进行模型参数的求解,推导了Hesse矩阵的相关参数,较好地解决了不规则曲面拟合的问题,进而实现了拼接渐晕的处理。实验结果表明:文中方法能够有效地估计退化模型的相关参数,处理后图像的信噪比提高了至少15 dB,有效地去除了拼接带来的渐晕失真,且达到实时应用的要求,具有广泛的应用价值。

Topic of the paper was to correct the vignetting of mosaic images based on reflector. The generation mechanism of the vignetting phenomenon was analyzed through geometrical optics, and the vignetting energy distribution model in the middle of the optical field was proposed. According to the analysis result, a degenerate model which was calculated by the steepest descent method was proposed. The parameters of Hesse matrix were deduced to solve the problem of irregular quadrics fitting, then to correct the vignetting. The experiment result illuminates that the parameters of the degenerate model can be estimated effectively, the image＇s SNR after correction can be increased by 15 dB, and the vignetting can be removed effectively. The method can work in real-time working mode, and has extensive application value.