反射式离轴数字全息再现像中的噪声抑制

Noise Suppression in Reflective Off-axis Digital Holographic Reconstruction

为了抑制反射式离轴数字全息再现像中的零级像和散斑噪声对再现像的影响,利用高斯核函数在空域对数字全息图进行低通滤波,再用原数字全息图减去滤波后的低频信息来抑制零级像,采用非局部均值滤波来抑制散斑噪声。实验结果表明空域高斯核函数处理法能有效地抑制零级像,非局部均值滤波可以抑制散斑噪声但对部分细节的保持能力不强,改进后的非局部均值滤波在抑制散斑噪声的同时能很好地保护细节信息,提高了离轴数字全息再现像的质量。

To suppress the zero-order image and speckle noise in reflective digital off-axis holography which have great impacts on the quality of reconstructed images,proposed is a new method,in which,firstly,the digital hologram is processed with Gaussian kernel function in spatial domain,then the original hologram is used to decrease the low-frequency information of the filtered hologram so as to suppress the zero-order image,lastly,a nonlocal means（NLM）filter is proposed to suppress speckle noise.Experimental results show that it is correct and effective to suppress the zero-order image by processing digital hologram with Gaussian kernel function in spatial domain and NLM filter can only suppress the speckle noise effectively.While the improved NLM filter can not only suppress the speckle noise,but also preserve details perfectly,so the quality of reconstructed image is improved effectively.