为减小并行相移数字全息重建过程中的插值误差、提高再现图像的质量,提出了一种基于全息图像条纹特性和像素分布的并行相移数字全息条纹分析插值算法。该算法首先根据相移特性从并行相移数字全息图中提取各同相全息图像,将各图像分为3×3的方块区域;按照全息条纹特性对分割的方块区域进行多方向插值,根据多方向插值后的图像频域特性进行选择性合并,生成新的全息再现物场。实验结果表明:与传统并行相移全息插值算法相比,所提算法可将再现图像的峰值信噪比提高45%以上;与其他改进算法相比,所提算法的计算时间缩短为原来的一半左右。所提算法能更好地重建并行相移数字全息图像,减小插值误差,保留细节信息,提高再现图像质量,可用于很多领域的动态三维物场信息的获取,如生物细胞观测、移动物体体检、微观粒子成像和跟踪等领域。

Reconstruction the computer generated Fresnel hologram of complex 3D object based on compressive sensing (CS) is presented. The hologram is synthesized from a color image and the depth map of the 3D object. With the depth map, the intensity of the color image can be divided into multiple slices, which satisfy the condition of the sparsity of CS. Thus, the hologram can be reconstructed at different distances with corresponding scene focused using the CS method. The quality of the recovered images can be greatly improved compared with that from the back-propagation method. What’s more, with the sub-sampled hologram, the image can be ideally reconstructed by the CS method, which can reduce the data-rate for transmission or storage.

An integrated method based on optical and digital image processing is presented to suppress speckle in digital holography. A spatial light modulator is adopted to introduce random phases to the illuminating beam. Multiple holograms are reconstructed and superimposed, and the intensity is averaged to smooth the noise. The adaptive algorithm based on the nonlocal means is designed to further suppress the speckle. The presented method is compared with other methods. The experimental results show that speckle reduction is improved, and the proposed method is effective and feasible.

提出了利用二维彩色图像和深度图生产计算菲涅耳全息图的方法。把二维彩色图像按深度图分为多层物面信息，并把每层物面深度值转换为菲涅耳衍射距离。根据层析法原理，采用单步菲涅耳衍射算法，即可得到三维场景的计算全息图。研究结果显示该方法可以正确地对复杂三维场景进行全息图的记录和再现。利用强度叠加法对再现像进行散斑去除，提高了再现三维图的质量。