A fast blind denoising method for grating image
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摘要:基于正弦光栅条纹投影的三维测量技术是当前研究的热点问题。然而,受噪声的影响,采集到的光栅条纹图像质量降低,导致提取的相位发生扰动,而相位的提取结果直接决定着测量结果的准确性。实际测量中噪声未知,针对这一问题,本文提出了一种盲去噪方法。首先,根据残差模型,完成光栅条纹图像的真值图像与噪声图像的分离,然后,引入主成分分析技术估计出噪声图像的方差值。最后,根据噪声方差的估计值,利用基于相图的高斯滤波方法,将针对多帧光栅图像的噪声滤波转换到提取的相位图上完成。由实验结果可知,和对比方法相比,本文方法的均方根相位误差最高下降了88.5%,所提方法处理后的相位更加接近测量体的真值相位。本文方法可在最短的执行时间内实现对噪声导致的相位扰动进行抑制。所提方法能够快速处理光栅图像噪声引起的相位误差,在光栅投影测量中具有较强的实用性。Abstract:The three-dimensional measurement technology based on the projection of sine grating fringe image is a hot-topic. However, due to the influence of noise, the quality of the captured grating image is worse, resulting in the disturbance of the extracted phase, which directly determines the accuracy of the measurement. Since the noise is unknown in actual measurement, a blind denoising method is proposed in this paper. Firstly, according to the residual model, the grating fringe image is separated into the true value and the noise, then the Principal Component Analysis (PCA) technology is introduced to estimate the variance of the noise. Finally, according to the estimated value of the variance, the filtering on multi-frame fringe images is replaced by employing Gaussian filtering on the phase map. In contrast to other methods, the results of the proposed method showed that the Root Mean Square Error (RMSE) decreased by 88.5% (up to most), which indicated that the phase values of the proposed method were closer to the ground-truth of the measured object. By employing the proposed method, the phase disturbance caused by noise were significantly suppressed in the shortest execution time. The proposed method can quickly deal with the phase error caused by the noise of the grating image and has strong practicability in the grating image projection measurement.
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Key words:
- grating image/
- blind denoising/
- PCA/
- phase map filtering
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表 1仪器设备型号和参数
Table 1.The instrument types and parameters
仪器设备 型号 主要性能及参数 投影仪 DLP4500 分辨率912 pixel×1140 pixel 工业相机 MV-UB130M 分辨率1024 pixel×1280 pixel
曝光时间:200 ms
帧率:30 frame/s
信噪比:45 dB电脑 Intel Core (TM)
i5-8250U CPU主频:1.6 GHz 表 2各种方法的噪声方差估计值
Table 2.The estimated noise variances of different methods
表 3几种算法的量化指标对比
Table 3.Comparison of quantitative indicators for different methods
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