多通道宽响应域TDI CCD成像系统的非均匀性校正

Non-Uniformity Correction for Multi-Channel TDI CCD Imaging System in Wide Response Range

针对时间延迟积分(TDI)电荷耦合器件(CCD)成像系统多通道间存在响应非均匀问题,开展了基于辐射定标的校正方法研究。结合成像系统的信号处理流程,推导了响应非均匀性校正的理论模型,提出了一种基于加权最小二乘的定标校正方法,分别在1/4、1/2和3/4饱和响应处采集三组图像数据,并利用高斯加权函数对三组通道间的校正参数进行加权最小二乘拟合,从而获得优化的校正参数。利用TDI CCD成像系统进行实验验证,结果表明,系统的响应非均匀性(1/2饱和响应处)由原来的4.09%降低至0.85%,并优于两点校正法的1.93%,同时该方法在宽响应域内均获得了良好的校正效果,具有精度高、实用性强等特点,可应用于机载、星载等相机载荷,为获取高质量的遥感图像数据奠定技术基础。

There is a problem of non-uniformity response between multiple channels for a time-delayed integration （TDI） charge-coupled device （CCD） imaging system. Due to this problem, a correction method research based on radiometrie calibration is conducted. A theoretical model for correction is deduced according to the flow of signal processing. A correction method is proposed based on weighted least square, which needs to acquire three sets of image data in 1/4, 1/2 and 3/4 saturation. Three sets of correction parameters are fitted by weighted least square using Gaussian weighting function to achieve the optimized parameters. The experimental verification is carried out using a TDI CCD imaging system. The results show that the photo response non-uniformity reduces from 4.09% to 0.85%, which is better than 1. 93% obtained by two-point correction method. And it has a good performance in wide response range with advantages of high precision and good practicability. This method can be applied in many kinds of airborne or spaceborne camera payloads and lay the technical foundation to achieve high-quality remote sensing image data.