基于立方型相位板调制的波前编码图像恢复

Image restoration of wavefront coding system with a cubic phase mask

针对立方型相位板对光瞳调制具有非旋转对称性及实际相位板方位测试困难从而导致实际波前编码系统后续图像不能准确恢复的问题,提出了以灰度梯度向量模方和为判据的等增量旋转调整点扩散函数(PSF)的维纳滤波方法。对于手持式裂缝检测波前编码系统的图像恢复,以ZEMAX软件设计得到的PSF为基础,根据立方型相位板PSF的旋转性质,进行旋转增量修正,并使用循环边界的方法消除截断振铃效应,来提高图像恢复的质量。实验表明,改进算法可以有效地修正系统的PSF,对波前编码实际系统图像的恢复有很好的适用性。

Since the pupil of the wavefront coding system with a cubic phase mask is not modulated in the form of rotational symmetric phase modulation and it is difficult to accurately demarcate the azimuth of the phase mask in an actual system,the subsequent image restoration is always not satisfied.So we design a Wiener filtering method by rotating the PSF by a regular increase in azimuth angle under the criterion of the vector norm sum of image gray gradation.We get the initial PSF of the wavefront coding system from the ZEMAX optical design and modify it according to its rotational character until we get the good result in the vector norm sum of gray gradation.Meanwhile we reduce the effect of boundary truncation with boundary cycle technology to improve the quality of image restoration.The results show that it is effect to adjust the PSF with the modified algorithm and the same consideration is quite applicable to image restoration of other actual wavefront coding system.