一种改进的空间相机在轨调制传递函数检测方法

Improved Method for On-Orbit Modulation Transfer Function Detection of Space Cameras

根据空间探测相机在轨工作状态及成像特点,结合调制传递函数(MTF)常用测试方法,利用月球边缘刃边法,对其进行了在轨MTF检测。该方法将月球边缘与深空背景形成的高对比度线状边缘图像作为测试目标,使用仿真手段分析每个环节多种处理方法的计算精度及运行速度,形成了优化的月球边缘刃边法在轨MTF检测流程,其中在边缘扩展函数(ESF)处理环节,使用修正的Savitsky-Golay滤波器组合双高斯拟合法,得到了准确的ESF,同时有效抑制了噪声。仿真和实验结果表明,该方法对信噪比高于30 dB图像的测试精度达到0.02,能实现相机焦面位置和MTF的准确标定。

According to the on-orbit working state and imaging characteristics of cameras for space exploration, the lunar edge method is used to detect its on-orbit modulation transfer function (MTF), combined with the commonly used test method of MTF. This method uses the high-contrast linear edge image formed by the lunar edge and the deep space background as the test target. The simulation is used to analyze the calculation precision and running speed of various processing methods in each link, forming an optimized process of on-orbit MIT detection based on the lunar-edge method. In the link of edge spread function (ESF) processing, a modified Savitsky-Golay filter combined with double Gaussian fitting method is used to obtain an accurate ESF while effectively suppressing the noise. The simulation and experimental results show that the proposed method has an accuracy of 0.02 for images with a signal-to-noise ratio higher than 30 dB, which can achieve accurate calibration of camera focal plane position and MTF.