基于快速傅里叶变换的条纹图像处理研究

为提高船体扭转角变形测量精度,对双光栅干涉测量法产生的莫尔条纹采用快速傅里叶变换频域处理。采集不同宽度的莫尔条纹图像,分别对图像进行快速傅里叶变换,对比分析图像频谱,得到实际莫尔条纹图像的有效频率信息。分析滤波器的选择原则,选用陷波低通滤波器,去除频域图像中高频噪声,获得莫尔条纹有效信息。实验结果表明,莫尔条纹的频域处理精度远高于空域处理结果,使扭转角测量精度提高到1.2″。

Researeh on processing of fringe image by fast Fourier transform

To enhance measurement precision of ship's torsion angle,using Fast Fourier Transform(FFT) process moiré fringe generated by two gratings interference.Grabbed moiré fringes with different width in experiments,carried out FFT,compared and analyzed frequency image,the effective frequency information of real moiré fringe are got.The choosing principle of filter is presented.Notch low-pass filter is used.High-frequency noises are removed.The effective information are obtained.Experiment results show that the frequency domain processing precision of moiré fringe is far higher than air zone processing result.Torsion angle measuring precision is enabled to achieve 1.2″.