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为了测算中分辨率光谱成像仪在轨调制传递函数(MTF),提出了一种基于图像中非理想阶跃目标的处理方法。利用仅一侧具有较好均匀性的目标,在线扩散函数(LSF)的对称性假设下,实施基于阶跃响应思想的测算方法。与传统的阶跃边缘法相比,该方法得到的结果与中分辨率光谱成像仪获得的结果一致。将其应用在中分辨率光谱成像仪的指标考核中,得到的半峰全宽(FWHM)与传统处理方法仅相差0.03 pixel,奈奎斯特频率处的MTF值也仅相差0.02,验证了本文方法的有效性。该方法所利用的目标在中分辨率光谱成像仪遥感图像中极为常见,因而普适性更好。
In order to measure in-orbit modulation transfer function (MTF) of medium-resolution spectral imager, a method based on non-ideal step target in image is proposed. Based on the symmetry assumption of on-line diffusion function (LSF), the method based on the idea of step response is implemented by using the target with good uniformity on only one side. Compared with the traditional step-edge method, the result obtained by this method is consistent with that obtained by the medium-resolution spectral imager. The application of FWHM to the index of medium-resolution spectral imager shows that the FWHM is only 0.03 pixels away from the traditional processing method and the MTF value at the Nyquist frequency is only 0.02, The effectiveness of the method. The target used by this method is very common in remote sensing images of medium-resolution spectral imager, so it is more universal.