TDICCD相机平台振动所致的MTF空间移变降质

卫星振动不仅会引起TDI(Time Delay and Integration)CCD相机像元采样的不规则性,还会引起像元弥散斑空间分布的不一致性,导致图像传递函数(Modulation Transfer Function,MTF)产生空间变化,从而制约高分辨率图像振动复原质量。本文从卫星振动对TDICCD相机推扫成像采样过程的作用机理出发,结合理论推导与仿真研究,得到了平台振动引起的图像空间移变降质及表征方法。然后在振动复原模型的基础上,推导得出MTF空间移变降质对复原处理误差的影响,并基于实际卫星图像开展了复原实验。实验结果表明:当振动所致图像MTF空间移变降质小于15%时,复原处理后的图像与理想图像的结构相似度优于0.95,而且处理误差所导致的图像失真不影响判读质量。

MTF space-variant blurring resulted from platform vibration of TDICCD camera

The satellite vibration could not only result in the irregularity of pixel sampling of TDI(Time Delay and Integration)CCD camera and the inconsistency of spatial distribution of pixel disc of confusion, but also could make the Modulation Transfer Function (MTF)of image generate space variation caused hereby. Consequently, the restoration quality by vibration of high-definition image may be limited. Starting with the action mechanism of satellite vibration on sampling process of push-scanning image by TDICCD camera and combined with theoretical derivation and simulation research, this paper obtained the blurring and characterization methods of space variance of image resulted from platform vibration. Then, based on restoration model of vibration, the influences of MTF space-variant blurring on restoration processing errors were deduced and obtained. In addition, according to the actual satellite image, the restoration experiment was carried out. The experimental results indicate that: when the MTF space-vibrant blurring of image is lower than 15%, because of vibration, the structural similarity between image which has been treated by restoration and ideal image may be superior to 0.95, and the image distortion caused by processing error may not impact interpretation quality.