基于CCD标定的微像素精度图像定位技术

MicroPixel Accuracy Point Target Positioning Technology Based on CCD Calibration

摘要:

基于光电成像器件CCD的点目标定位技术被广泛运用于天文定位、侦察等民用及军用方面。传统点目标定位精度一般为亚像素级,受CCD自身成像误差限制,目标定位精度难以大幅提高。提出通过干涉条纹对CCD进行标定,从而得到CCD频域像素响应函数的精确表达式,由此重构高质量的目标入射光场图像,进而提高光电成像系统对点目标定位的精度。首先建立了干涉条纹标定CCD及目标光场图像重构的理想模型,并通过仿真验证了点目标图像重构效果以及最终点目标的定位精度。仿真结果表明,经干涉条纹标定CCD后,重构的目标光场图像质量得到大幅度的提升,接近于CCD像面前入射光场图像,通过高斯曲面拟合得到点目标形心坐标及其微位移的提取精度均达微像素级别,相比于传统的亚像素定位,定位精度得到了大幅度的提高。

Abstract:

Pointtarget positioning technology based on CCD is widely used in civil and military fields such as astronomical positioning, reconnaissance, etc. The accuracy of traditional point target positioning is generally subpixel level, and it is difficult to be significantly improved because of the selfimaging errors of CCD. In this paper, a method was proposed to accurately calibrate the CCD error through interference fringes and reconstruct the highquality target image, so as to achieve the micropixel level accuracy. Firstly, an ideal model based on CCD calibration with interference fringes and target image reconstruction was established, then the accuracy of different displacements of point target at long distance was verified with numerical simulation. The results show that the quality of the reconstructed target images is greatly improved after the CCD is calibrated by interference fringes, which is close to the incident light field image before the CCD plane. The accuracy of the point target centroid and small displacement extraction both reaches 10-6 pixels, which has been greatly improved compared to that of the traditional subpixel positioning.