FY-2卫星热红外波段MTF在轨评价及其在改进图像质量中的应用

提出了基于理想斜坡模型及目标延拓空间卷积变换的采样成像系统热红外波段MTF在轨评价方法.仿真结果表明,该方法对性能良好的成像系统而言,系统特征MTF值的绝对评价误差约0.05.同时,利用2006～2008年间的观测数据,定量评价了FY-2C卫星热红外通道的系统MTF特性,与卫星发射前地面测试结果基本一致.采用在轨评价得到的系统点源扩展函数(PSF),对FY-2C卫星热红外通道图像进行了复原处理,得到了清晰度更高的图像产品,并给出了对典型台风监测结果的改进.传统在轨MTF评价方法中采用的理想阶跃模型,可视为理想斜坡模型中参数Nslope为0时的特例.因此,该方法同样适用于可见光、近红外波段的在轨MTF评价.

ON-ORBIT MTF EVALUATION FOR THERMAL INFRARED BAND OF FY-2 SATELLITE AND ITS APPLICATION IN IMAGE QUALITY IMPROVEMENTS

Based on an ideal slope-profile model as well as spatial convolution transform with target extension, a MTF ap- proach was proposed to solve on-orbit evaluation for thermal infrared band of sampled imaging system. Simulation results show that the absolute evaluation error of the system MTF at half normalized spatial frequency is about 0.05 for an ordinary system with good performance. Meanwhile, the system MTF characteristics of FY-2C satellite thermal infrared band (IR1) were quantitatively evaluated with observed data from 2006 to 2008, which is consistent with those measured by on ground testing. By using the derived system point spread function(PSF), the images of FY-2C IR1 were recovered with more detailed textures. It improves the monitoring performance for some typical typhoon. The ideal step-profile model used in the traditional on-orbit MTF evaluation can be regarded as a special case of the proposed ideal slope-profile one where the parameter N slope equals zero. Therefore, the proposed method is also suitable for on-orbit MTF evaluation of visible and near-infrared bands.