基于经验模式分解的CCD器件自适应非均匀性校正方法研究

CCD Nonuniformity Adaptive Correction Method Based on Empirical Mode Decomposition

针对高精度测试系统中电荷耦合器件(CCD)的非均匀性会给测试结果带来较大误差,根据引起非均匀性的噪声特性,建立了对应的图像模型。根据传统两点线性法的基本思想,提出了一种基于经验模式分解(EMD)的自适应分析方法对非均匀性像素进行校正。该算法以Hilbert-Huang变换(HHT)中的滤波器理论为基础,将图像序列在时间域的尺度分解和相应统计量计算,获得用于图像校正的偏置和增益系数。通过实际实验对所提算法进行了验证,结果表明,该算法能够有效地校正像素的非均匀性,提高了测试精度。

In the high-precision measurement system,the charge coupled device（CCD） nonuniformity will give a greater margin of error to measurement results.According to the characteristic of noise leading to the image pixels nonuniformity,the corresponding image model is established.According to the traditional two-point linear correction method,an adaptive correction method is put forward,in which the Hilbert-Huang（HHT） filter theory is applied.With the scale decomposition of image sequences on the time domain and the corresponding statistics calculation,the offset and gain coefficients in CCD image are obtained.In experiments the high speed area array CCD is adopted to acquire images with the circular facula launched by the laser,and the algorithm is verified by calculating the facula central coordinates of the image.The results show that the algorithm can correct pixel nonuniformity effectively.The algorithm proposed is better than the algorithm for nonuniformity correction using linear model.The experimental result shows the superiority of the algorithm.